@article{forrester_fraver_mladenoff_gower_d'amato_lindner_2023, title={Experimental Evidence that Forest Structure Controls Detrital Decomposition}, volume={4}, ISSN={["1435-0629"]}, url={https://doi.org/10.1007/s10021-023-00841-5}, DOI={10.1007/s10021-023-00841-5}, journal={ECOSYSTEMS}, author={Forrester, J. A. and Fraver, S. and Mladenoff, D. J. and Gower, S. T. and D'Amato, A. W. and Lindner, D. L.}, year={2023}, month={Apr} }
 @article{perreault_forrester_mladenoff_gower_2021, title={Linking deadwood and soil GHG fluxes in a second growth north temperate deciduous forest (Upper Midwest USA)}, volume={8}, ISSN={["1573-515X"]}, DOI={10.1007/s10533-021-00839-y}, journal={BIOGEOCHEMISTRY}, author={Perreault, Lili and Forrester, Jodi A. and Mladenoff, David J. and Gower, Stith T.}, year={2021}, month={Aug} }
 @article{hunt_gower_nadelhoffer_lajtha_townsend_brye_2016, title={Validation of an agroecosystem process model (AGRO-BGC) on annual and perennial bioenergy feedstocks}, volume={321}, ISSN={["1872-7026"]}, DOI={10.1016/j.ecolmodel.2015.10.029}, abstractNote={Corn (Zea mays L.) residues and perennial C4 grasses are two Midwest bioenergy feedstock candidates due to their compatibility with agricultural infrastructure and potential for ecosystem service delivery. We validated the ecosystem process model AGRO-BGC by comparing model estimates with empirical observations from corn and perennial C4 grass systems across Wisconsin and Illinois under no-tillage, nitrogen fertilized, and unfertilized management. Validation parameters included soil organic carbon (SOC), total soil nitrogen (N) to 1.2 m, aboveground net primary productivity (ANPP), net ecosystem productivity (NEP), and leaf area index (LAI). We parameterized AGRO-BGC to represent ecophysiological characteristics of corn and perennial prairie grasses, and constructed scenarios to represent corresponding edaphic, climate, and management conditions. Unfertilized annual model estimates had normalized mean average errors relative to field measurements of 0.3, 23, and 4 t ha−1 for ANPP, SOC, and N, respectively. Fertilized simulations erred from observations by 0.6, 29, 5 t ha−1 for ANPP, SOC, and N, respectively. We also estimated long-term implications of varying residue removal rates on SOC. Model estimates compared to field data tested the hypothesis that long-term increased residue removal decreases SOC. Field observations showed 0.17, 0.09, and a −0.17 t C ha−1 yr−1 change for control, harvest, and bare grass residue removal treatments, respectively. Simulated SOC loss was greatest for the most intensive residue removal scenarios (−0.48 and −0.68 t C ha−1 yr−1 for corn and grass, respectively), compared to no-harvest scenarios that increased SOC by 0.05 t C ha−1 yr−1 for both corn and grass. AGRO-BGC estimated a 0.07 t C ha−1 yr−1 loss under corn residue harvest, while estimating 0.09 t C ha−1 yr−1 loss for grass. Results suggest long-term increased corn and grass residue harvest (beyond grain) for biofuel feedstock will decrease SOC and soil productivity by approximately 15% in corn and 21% in grass systems over 47 years.}, journal={ECOLOGICAL MODELLING}, author={Hunt, Natalie D. and Gower, Stith T. and Nadelhoffer, Knute and Lajtha, Kate and Townsend, Kimberly and Brye, Kristofor R.}, year={2016}, month={Feb}, pages={23–34} }
 @article{nunes_gower_peckham_magalhaes_lopes_rego_2015, title={Estimation of productivity in pine and oak forests in northern Portugal using Biome-BGC}, volume={88}, ISSN={["1464-3626"]}, DOI={10.1093/forestry/cpu044}, abstractNote={Escola Superior Agraria/Instituto Politecnico de Viseu (ISPV), Estrada de Nelas, Quinta da Alagoa, Viseu 3500-606, Portugal Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Universityof Tras-os-Montes and Alto Douro, UTAD, Quinta de Prados, Vila Real 5000-801, Portugal CEABN, Instituto Superior de Agronomia, Tapada da Ajuda, Lisboa 1349-017, Portugal College of Natural Resources, North Carolina State University, Campus Box 8001, Raleigh, NC 27695-8001, USA Department of Botany, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, USA}, number={2}, journal={FORESTRY}, author={Nunes, Leonia and Gower, Stith T. and Peckham, Scott D. and Magalhaes, Marco and Lopes, Domingos and Rego, Francisco Castro}, year={2015}, month={Apr}, pages={200–212} }
 @article{donovan_eaton_gower_jenkins_lamar_poli_sheehy_wojdak_2015, title={QUBES: a community focused on supporting teaching and learning in quantitative biology}, volume={2}, ISSN={2373-7867}, url={http://dx.doi.org/10.1080/23737867.2015.1049969}, DOI={10.1080/23737867.2015.1049969}, abstractNote={This letter provides an overview of the Quantitative Undergraduate Biology Education and Synthesis (QUBES) Project funded through the National Science Foundation. The project has five distinct, but interdependent, initiatives which work together to support faculty and students in the teaching and learning of quantitative biology (QB). QUBES has adopted an integrated strategy to improving the frequency and effectiveness of QB instruction that includes coordinating a broad consortium of professional stakeholders, supporting faculty development and the implementation of new teaching practices, providing an infrastructure for collaboration and access to high quality materials, establishing new metrics for faculty teaching scholarship and documenting the project outcomes.}, number={1}, journal={Letters in Biomathematics}, publisher={Informa UK Limited}, author={Donovan, Sam and Eaton, Carrie Diaz and Gower, Stith T. and Jenkins, Kristin P. and LaMar, M. Drew and Poli, DorothyBelle and Sheehy, Robert and Wojdak, Jeremy M.}, year={2015}, month={Jan}, pages={46–55} }
 @article{lewandowski_forrester_mladenoff_stoffel_gower_d’amato_balser_2015, title={Soil microbial community response and recovery following group selection harvest: Temporal patterns from an experimental harvest in a US northern hardwood forest}, volume={340}, ISSN={0378-1127}, url={http://dx.doi.org/10.1016/J.FORECO.2014.12.012}, DOI={10.1016/J.FORECO.2014.12.012}, abstractNote={Forest harvesting and the associated loss of nutrients and carbon has the potential to negatively affect the soil microbial community, which plays a significant role in the health and productivity of the forest ecosystem. We used an experiment to evaluate the effects of group selection using whole-tree harvesting on the soil microbial community in a second growth northern hardwood forest dominated by sugar maple (Acer saccharum Marsh.) in northern Wisconsin, USA. We compared the response of the soil microbial community in 200 m2 and 380 m2 harvested gaps to unharvested controls during the spring and summer in the first two years post-harvest, and continued to monitor changes in the soil microbial communities and microenvironment in 380 m2 gaps in years four, five, and seven post-harvest. Changes in community size and composition were assessed using phospholipid fatty acid (PLFA) analysis. We found that the abundance of arbuscular mycorrhizal fungi initially decreased following harvest, while abundance of anaerobic and gram positive bacteria, and the cyclo/pre-cyclo microbial stress ratio increased; responses that can be linked to microclimatic variability and resource accessibility. Neither actinomycete bacteria nor saprotrophic fungi exhibited an initial response to harvest, but in later years, we observed a decrease in actinomycetes and an increase in fungal abundance, suggesting a competitive interaction between the two main complex carbon-utilizing microbial groups. Canopy gap size had a minimal effect on the soil microbial community, resulting in a higher microbial stress ratio in 200 m2 gaps. The microbial community exhibited seasonal and yearly fluctuation, which reinforces the need for repeated sampling over multiple seasons to correctly interpret management effects. Despite the large amount of seasonal and yearly variability, we began to see signs of recovery in the soil microbial community between two and four years post-harvest. We conclude that group selection accomplished via whole-tree harvesting of this size and scale does not result in long-term effects on the soil microbial community in this temperate northern hardwood forest.}, journal={Forest Ecology and Management}, publisher={Elsevier BV}, author={Lewandowski, Tera E. and Forrester, Jodi A. and Mladenoff, David J. and Stoffel, Jennifer L. and Gower, Stith T. and D’Amato, Anthony W. and Balser, Teri C.}, year={2015}, month={Mar}, pages={82–94} }
 @article{forrester_mladenoff_d'amato_fraver_lindner_brazee_clayton_gower_2015, title={Temporal trends and sources of variation in carbon flux from coarse woody debris in experimental forest canopy openings}, volume={179}, ISSN={["1432-1939"]}, DOI={10.1007/s00442-015-3393-4}, abstractNote={Pulses of respiration from coarse woody debris (CWD) have been observed immediately following canopy disturbances, but it is unclear how long these pulses are sustained. Several factors are known to influence carbon flux rates from CWD, but few studies have evaluated more than temperature and moisture. We experimentally manipulated forest structure in a second-growth northern hardwood forest and measured CO2 flux periodically for seven growing seasons following gap creation. We present an analysis of which factors, including the composition of the wood-decay fungal community influence CO2 flux. CO2 flux from CWD was strongly and positively related to wood temperature and varied significantly between substrate types (logs vs. stumps). For five growing seasons after treatment, the CO2 flux of stumps reached rates up to seven times higher than that of logs. CO2 flux of logs did not differ significantly between canopy-gap and closed-canopy conditions in the fourth through seventh post-treatment growing seasons. By the seventh season, the seasonal carbon flux of both logs and stumps had decreased significantly from prior years. Linear mixed models indicated the variation in the wood inhabiting fungal community composition explained a significant portion of variability in the CO2 flux along with measures of substrate conditions. CO2 flux rates were inversely related to fungal diversity, with logs hosting more species but emitting less CO2 than stumps. Overall, our results suggest that the current treatment of CWD in dynamic forest carbon models may be oversimplified, thereby hampering our ability to predict realistic carbon fluxes associated with wood decomposition.}, number={3}, journal={OECOLOGIA}, author={Forrester, J. A. and Mladenoff, D. J. and D'Amato, A. W. and Fraver, S. and Lindner, D. L. and Brazee, N. J. and Clayton, M. K. and Gower, S. T.}, year={2015}, month={Nov}, pages={889–900} }
 @article{wang_mladenoff_forrester_blanco_scheller_peckham_keough_lucash_gower_2014, title={Multimodel simulations of forest harvesting effects on long-term productivity and CN cycling in aspen forests}, volume={24}, ISSN={["1939-5582"]}, DOI={10.1890/12-0888.1}, abstractNote={The effects of forest management on soil carbon (C) and nitrogen (N) dynamics vary by harvest type and species. We simulated long‐term effects of bole‐only harvesting of aspen (Populus tremuloides) on stand productivity and interaction of CN cycles with a multiple model approach. Five models, Biome‐BGC, CENTURY, FORECAST, LANDIS‐II with Century‐based soil dynamics, and PnET‐CN, were run for 350 yr with seven harvesting events on nutrient‐poor, sandy soils representing northwestern Wisconsin, United States. Twenty CN state and flux variables were summarized from the models' outputs and statistically analyzed using ordination and variance analysis methods. The multiple models' averages suggest that bole‐only harvest would not significantly affect long‐term site productivity of aspen, though declines in soil organic matter and soil N were significant. Along with direct N removal by harvesting, extensive leaching after harvesting before canopy closure was another major cause of N depletion. These five models were notably different in output values of the 20 variables examined, although there were some similarities for certain variables. PnET‐CN produced unique results for every variable, and CENTURY showed fewer outliers and similar temporal patterns to the mean of all models. In general, we demonstrated that when there are no site‐specific data for fine‐scale calibration and evaluation of a single model, the multiple model approach may be a more robust approach for long‐term simulations. In addition, multimodeling may also improve the calibration and evaluation of an individual model.}, number={6}, journal={ECOLOGICAL APPLICATIONS}, author={Wang, Fugui and Mladenoff, David J. and Forrester, Jodi A. and Blanco, Juan A. and Scheller, Robert M. and Peckham, Scott D. and Keough, Cindy and Lucash, Melissa S. and Gower, Stith T.}, year={2014}, month={Sep}, pages={1374–1389} }
 @article{forrester_lorimer_dyer_gower_mladenoff_2014, title={Response of tree regeneration to experimental gap creation and deer herbivory in north temperate forests}, volume={329}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2014.06.025}, abstractNote={Structural heterogeneity has become a goal of contemporary forest management, yet the effect of incorporating variable sized canopy openings characteristic of older forests on ecosystem services is still largely unknown. Single-tree selection silviculture reduces tree species diversity, and group-selection harvests often produce inconsistent results in maintaining the proportion of species with low or intermediate shade tolerance. It is unclear how much variability is related to inherent growth rate differences among shade tolerance classes, asymmetric competition, sprouting behavior, herbivory, and other factors. We conducted an experiment to control several of these factors. The northern hardwood study area in north-central Wisconsin included 15 replicates of each of 3 sizes of experimental gaps (50 m2, 200 m2, and 380 m2). Ten main plots (80 × 80 m2) were fenced to exclude deer. Vertical height growth of saplings and stump sprouts was monitored for two years pre-treatment and four years post-treatment. Overstory gaps significantly increased height growth rates, but there was no significant difference between rates of the very shade-tolerant Acer saccharum and several midtolerant species in any gap size. Saplings dominated the regeneration layer in small gaps. Stump sprouts were more abundant and grew faster than saplings in large gaps, but after 4 years, A. saccharum advance regeneration still predominated in the upper height classes. Deer had limited effects on sapling development or species composition because tall advance regeneration was beyond their reach, but they severely affected the sprout layer. In unfenced plots, the unpalatable Ostrya viriginiana had the tallest sprouts. Overall, midtolerant species made up about 16% of the gap regeneration layer and appear to be increasing their proportion over time. Height growth rates of many saplings and sprouts exceeded 50 cm per year, suggesting that successful gap capture would be likely for both shade-tolerance groups under current environmental conditions. The non-significant difference in growth rates between shade-tolerant and midtolerant species across the light gradient could change as more time elapses since gap creation. However, our findings after four years are consistent with other studies in suggesting that there may be no consistent trends in the relative growth responses of shade-tolerant and midtolerant tree species to increased light and gap size.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Forrester, Jodi A. and Lorimer, Craig G. and Dyer, Jacob H. and Gower, Stith T. and Mladenoff, David J.}, year={2014}, month={Oct}, pages={137–147} }
 @article{vogel_bronson_gower_schuur_2014, title={The response of root and microbial respiration to the experimental warming of a boreal black spruce forest}, volume={44}, ISSN={["1208-6037"]}, DOI={10.1139/cjfr-2014-0056}, abstractNote={ We investigated the effects of a 5 °C soil + air experimental heating on root and microbial respiration in a boreal black spruce (Picea mariana (Mill.) B.S.P.) forest in northern Manitoba, Canada, that was warmed between 2004 and 2007. In 2007, the 14C/12C signatures of soil CO2 efflux and root and soil microbial respiration were used in a two-pool mixing model to estimate their proportional contributions to soil CO2 efflux and to examine how each changed in response to the warming treatments. In laboratory incubations, we examined whether warming had altered microbial respiration rates or microbial temperature sensitivity. The 14C/12C signature of soil CO2 efflux and microbial respiration in the heating treatments were both significantly (p < 0.05) enriched relative to the control treatment, suggesting that C deposited nearer the atmospheric bomb peak in 1963 contributed more to microbial respiration in heated than control treatments. Soil CO2 efflux was significantly greater in the heated than control treatments, suggesting the acclimation to temperature of either root or microbial respiration was not occurring in 2007. Microbial respiration in laboratory incubations was similar in heated and control soils. This study shows that microbial respiration rates still responded to temperature even after 4 years of warming, highlighting that ecosystem warming can cause a prolonged release of soil organic matter from these soils. }, number={8}, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={Vogel, Jason G. and Bronson, Dustin and Gower, Stith T. and Schuur, Edward A. G.}, year={2014}, month={Aug}, pages={986–993} }
 @article{nunes_lopes_rego_gower_2013, title={Aboveground biomass and net primary production of pine, oak and mixed pine-oak forests on the Vila Real district, Portugal}, volume={305}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2013.05.034}, abstractNote={Pine and oak are common tree species in the Vila Real district, northern Portugal, a region where forests are an important land use (38%). The net primary production (NPP) of these forests is not well known. The objective of this study was to quantify the aboveground biomass and aboveground NPP (ANPP) of pine (Pinus pinaster Aiton), pyrenean oak (Quercus pyrenaica Willd.) and mixed pine–oak forests in the Vila Real district and to evaluate the relationships between ANPP and their stand characteristics. To achieve this objective, 15 stands of pine, 15 stands of oak and 9 stands of mixed pine–oak were studied between 2008 and 2011. ANPP average (and range) of pine, oak and mixed stands were 7.9 (2.9–15.1), 7.3 (3.0–12.1), and 12.1 (6.5–17.2) Mg ha−1 yr−1, respectively. An analysis of covariance (ANCOVA), to reduce the within-groups variability and detect the differences between the stand compositions, was performed. In this analysis, we rejected the null hypothesis that the composition stands had the same mean among ANPP. Mixed stands had a significantly higher mean ANPP than pine or oak. Also, we verified that in pine, the greater distribution of biomass was on the stem (4.0 ± 0.7 Mg ha−1 yr−1, 50% of the total productivity) component where carbon sequestration is retained longer, whereas in oak and mixed stands the foliage was the component with the greater distribution of biomass (4.0 and 6.0 Mg ha−1 yr−1, respectively). Aboveground biomass was significantly different among the three stands types and averaged 83.4, 61.4 and 110.5 Mg ha−1 for pine, oak and mixed stands, respectively. Regression models performed showed that there was a strong relationship between aboveground biomass and basal area in all stands. This study concludes that the production efficiency, defined as stem productivity/leaf area index, was significantly different in mixed stands. Pine had the greatest production efficiency in all stand types and, in mixed stands, had 85% of the total production efficiency.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Nunes, Leonia and Lopes, Domingos and Rego, Francisco Castro and Gower, Stith T.}, year={2013}, month={Oct}, pages={38–47} }
 @article{forrester_mladenoff_gower_2013, title={Experimental Manipulation of Forest Structure: Near-Term Effects on Gap and Stand Scale C Dynamics}, volume={16}, ISSN={["1435-0629"]}, DOI={10.1007/s10021-013-9695-7}, number={8}, journal={ECOSYSTEMS}, author={Forrester, Jodi A. and Mladenoff, David J. and Gower, Stith T.}, year={2013}, month={Dec}, pages={1455–1472} }
 @article{nunes_gower_monteiro_lopes_rego_2013, title={Growth dynamics and productivity of pure and mixed Castanea sativa Mill. and Pseudotsuga menziesii (Mirb.) Franco plantations in northern Portugal}, volume={7}, ISSN={["1971-7458"]}, DOI={10.3832/ifor1087-007}, abstractNote={Abstract: Since the late 1980’s the productivity of monocultures versus mixed-species forests has been the object of special interest and study by forest managers and ecologists. All over the world mixed plantations have been established in different proportions to analyse if mixtures can provide greater yields and more benefits than monocultures of the component species and also to understand if they can be an interesting economic option. An experimental design trial was set up in the north of Portugal in a replacement series with pure and mixed Castanea sativa Mill. and Pseudotsuga menziesii (Mirb.) Franco. The objective of this study was to assess growth dynamics and compare the aboveground biomass and net primary production of the two species in pure and mixed treatments in proportions 1:1 and 1:3. The growth was measured at 7, 11, 15, 17, 19, 27 and 28 years after planting and aboveground net primary production was estimated at age 28 years. As a component of the mixed treatments, P. menziesii exhibited greater height, diameter and aboveground biomass than C. sativa. Relative yield total indicated a higher productivity in the mixtures compared with the pure treatments. Early in the development the pure treatments had a similar aboveground biomass per hectare as the mixtures, but later the mixtures had more yield than the pure treatments. The mixture productivity increase trough time appears to be a result of both canopy stratification and better use of site resources. The aboveground net primary production was also higher in mixed than in the pure treatments. This study shows the importance of comparing mixed and pure stands.}, journal={IFOREST-BIOGEOSCIENCES AND FORESTRY}, author={Nunes, Leonia and Gower, Stith T. and Monteiro, Maria L. and Lopes, Domingos and Rego, Francisco C.}, year={2013}, month={Dec}, pages={92–102} }
 @article{peckham_gower_perry_wilson_stueve_2013, title={Modeling harvest and biomass removal effects on the forest carbon balance of the Midwest, USA}, volume={25}, ISSN={["1873-6416"]}, DOI={10.1016/j.envsci.2012.09.006}, abstractNote={The objective of this study was to use an ecosystem process model, Biome-BGC, to explore the effects of different harvest scenarios on major components of the carbon budget of 205,000 km2 of temperate forest in the Upper Midwest region of the U.S. We simulated seven harvest scenarios varying the (i) amount of harvest residue retained, (ii) total harvest area, and (iii) harvest type (clear-cut and selective) to assess the potential impacts on net biome production (NBP), net primary production (NPP), and total vegetation carbon. NBP was positive (C sink) in year 1 (2004) and generally decreased over the 50-year simulation period. More intensive management scenarios, those with a high percentage of clear-cut or a doubling of harvest area, decreased average NBP by a maximum of 58% and vegetation C by a maximum of 29% compared to the current harvest regime (base scenario), while less intensive harvest scenarios (low clear-cut or low area harvested) increased NBP. Yearly mean NPP changed less than 3% under the different scenarios. Vegetation carbon increased in all scenarios by at least 12%, except the two most intensive harvest scenarios, where vegetation carbon decreased by more than 8%. Varying the amount of harvest residue retention had a more profound effect on NBP than on vegetation C. Removing additional residue resulted in greater NBP over the 50-year period compared to the base simulation. Results from the seven model simulations suggest that managing for carbon storage and carbon sequestration are not mutually exclusive in Midwest forests.}, journal={ENVIRONMENTAL SCIENCE & POLICY}, author={Peckham, Scott D. and Gower, Stith T. and Perry, Charles H. and Wilson, Barry T. and Stueve, Kirk M.}, year={2013}, month={Jan}, pages={22–35} }
 @article{peckham_gower_2013, title={Simulating the effects of harvest and biofuel production on the forest system carbon balance of the Midwest, USA}, volume={5}, ISSN={["1757-1707"]}, DOI={10.1111/gcbb.12033}, abstractNote={Abstract}, number={4}, journal={GLOBAL CHANGE BIOLOGY BIOENERGY}, author={Peckham, Scott D. and Gower, Stith T.}, year={2013}, month={Jul}, pages={431–444} }
 @article{serbin_ahl_gower_2013, title={Spatial and temporal validation of the MODIS LAI and FPAR products across a boreal forest wildfire chronosequence}, volume={133}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2013.01.022}, abstractNote={The leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) absorbed by the vegetation are key biophysical measures of canopy foliage area and light harvesting potential. Accurately quantifying these properties is important for characterizing the dynamics of mass and energy exchanges between vegetation and the atmosphere. The overall objective of this research was to validate the spatial and temporal performance of the MODIS LAI/FPAR products for a boreal forest landscape in northern Manitoba, Canada. We examined both the MODIS collection 4 (C4) and updated collection 5 (C5) versions over a multiyear period (2004 to 2006) and spatially across seven different-aged forests originating from wildfire and ranging in age from 1- to 154-years-old. We made optical measurements of LAI and FPAR, which were empirically scaled to high-resolution imagery (ASTER; 15–30 m pixel size) to derive detailed reference LAI and FPAR maps. These maps were then aggregated to MODIS resolution (i.e. 1 km) for comparison. We characterized the temporal accuracy of the MODIS products using repeat measurements of LAI and FPAR, and through comparisons with continuously operating measurements of canopy light interception. MODIS captured the general phenological trajectory of these aggrading forests, however the MODIS LAI and FPAR products overestimated and underestimated the LAI and FPAR for the youngest and oldest sites, respectively. In addition, MODIS displayed larger seasonal variation in LAI and FPAR compared to field measurements for the needle-leaf evergreen dominated sites. The peak growing season difference between MODIS and spatially aggregated ASTER reference values of LAI and FPAR decreased significantly by 69% and 55%, respectively, for the updated C5 versus the previous C4 LAI/FPAR products. The overall uncertainty (i.e. RMSE) in the MODIS LAI retrievals decreased from 1.6 (C4) to 0.63 m2 m− 2 (C5) and from 0.20 (C4) to 0.07 (C5) for FPAR. The incorporation of understory vegetation into the validation of the MODIS products yielded significantly higher agreement between observed and MODIS values, likely due to the relatively open canopy architecture and abundant understory found within boreal forests.}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Serbin, Shawn P. and Ahl, Douglas E. and Gower, Stith T.}, year={2013}, month={Jun}, pages={71–84} }
 @article{bond-lamberty_bronson_bladyka_gower_2012, title={Corrigendum to “A comparison of trenched plot techniques for partitioning soil respiration” [Soil Biol. Biochem. 43 (10) (2011) 2108–2114]}, volume={47}, ISSN={0038-0717}, url={http://dx.doi.org/10.1016/j.soilbio.2011.11.003}, DOI={10.1016/j.soilbio.2011.11.003}, abstractNote={Corrigendum to “A comparison of trenched plot techniques for partitioning soil respiration” [Soil Biol. Biochem. 43 (10) (2011) 2108e2114] Ben Bond-Lamberty *, Dustin Bronson , Emma Bladyka , Stith T. Gower d a Joint Global Change Research Institute, DOE Pacific Northwest National Laboratory, 5825 University Research Court, Suite 1200, College Park, MD 20740, USA Department of Biology, University of Pennsylvania, 433 S. University Avenue, Philadelphia, PA 19104, USA Department of Botany and Program in Ecology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA Department of Forest and Wildlife Ecology, University of Wisconsin, 1630 Linden Drive, Madison, WI 53706, USA}, journal={Soil Biology and Biochemistry}, publisher={Elsevier BV}, author={Bond-Lamberty, Ben and Bronson, Dustin and Bladyka, Emma and Gower, Stith T.}, year={2012}, month={Apr}, pages={220} }
 @article{peckham_gower_buongiorno_2012, title={Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.}, volume={7}, DOI={10.1186/1750-0680-7-6}, abstractNote={Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production) and industrial (net emissions from forest industry) forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region.We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1). The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime.The forest's biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100 years increases the strength of the carbon sink, and that carbon sequestration and wood production are not conflicting for this particular forest ecosystem. The optimal harvest strategy found here may not be the same for all forests, but the methodology is applicable anywhere sufficient forest inventory data exist.}, number={6}, journal={Carbon Balance and Management}, author={Peckham, S and Gower, S. T. and Buongiorno, J.}, year={2012} }
 @article{forrester_mladenoff_gower_stoffel_2012, title={Interactions of temperature and moisture with respiration from coarse woody debris in experimental forest canopy gaps}, volume={265}, ISSN={["0378-1127"]}, DOI={10.1016/j.foreco.2011.10.038}, abstractNote={Coarse woody debris (CWD) and canopy gaps are thought to be important structural components that influence forest ecosystem processes, yet few studies have assessed whether these features interact to influence decay dynamics, and we know of none that does so under controlled experimental canopy gap conditions. By manipulating forest structure to create canopy openings, we tested whether canopy gaps, through their influence on microclimate, affect the respiration rate of CWD in a mature second-growth northern hardwood forest of Wisconsin, USA. We sought to determine the relative contribution of moisture or temperature as predictors of respiration, and to provide estimates of the annual C emission from CWD in these treatments. Differences in the surface temperature of CWD were apparent immediately following gap treatments, with debris in gaps staying significantly warmer than beneath undisturbed canopy. Coarse woody debris moisture content differed more between gaps and undisturbed canopy in the second post-treatment year due to higher insolation and temperature in gaps relative to undisturbed canopy. The gap treatment increased respiration rates and altered the relationship with CWD temperature and moisture in complex ways. The impacts of gap creation on C fluxes from CWD depended on the range of temperature and moisture being examined. The interaction of the temperature and moisture of the debris in combination with the decay class explained 60% of the observed variation in CWD respiration beneath undisturbed canopies. In gaps, only 23% of the variation of flux could be explained by environmental variables. Annual C fluxes were 128.2 g C kg−1 year−1 in canopy openings and 108.5 g C kg−1 year−1 in undisturbed canopy locations.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Forrester, Jodi A. and Mladenoff, David J. and Gower, Stith T. and Stoffel, Jennifer L.}, year={2012}, month={Feb}, pages={124–132} }
 @article{bond-lamberty_bronson_bladyka_gower_2011, title={A comparison of trenched plot techniques for partitioning soil respiration}, volume={43}, ISSN={["0038-0717"]}, DOI={10.1016/j.soilbio.2011.06.011}, abstractNote={Partitioning the soil surface CO2 flux (RS) flux is an important step in understanding ecosystem-level carbon cycling, given that RS is poorly constrained and its source components may have different sensitivities to climate change. Trenched plots are an inexpensive but labor-intensive method of separating the RS flux into its root (autotrophic) and soil (heterotrophic) components. This study tested if various methods of plant suppression in trenched plots affected RS fluxes, quantified the RS response to soil temperature and moisture changes, and estimated the heterotrophic contribution to RS. It was performed in a boreal black spruce (Picea mariana) plantation, using a randomized complete block design, during the 2007 and 2008 growing seasons. Trenched plots had significantly lower RS than control plots, with differences appearing ∼100 days after trenching; spatial variability doubled immediately after trenching but then declined throughout the experiment. Most trenching treatments had significantly lower (by ∼0.5 μmol CO2 m−2 s−1) RS than the controls, and there was no significant difference in RS among the various trenching treatments. Soil temperature at 2 cm explained more RS variability than did 10-cm temperature or soil moisture. Temperature sensitivity (Q10) declined in the control plots from ∼2.6 (at 5 °C) to ∼1.6 (at 15 °C); trenched plots values were higher, from 3.1 at 5 °C to 1.9 at 15 °C. We estimated RS for the study period to be 241 ± 40 g C m−2, with live roots contributing 64% of RS after accounting for fine root decay, and 293 g C m−2 for the entire year. These findings suggest that laborious hand weeding of trenched plot vegetation may be replaced by other methods, facilitating future studies of this large and poorly-understood carbon flux.}, number={10}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Bond-Lamberty, Ben and Bronson, Dustin and Bladyka, Emma and Gower, Stith T.}, year={2011}, month={Oct}, pages={2108–2114} }
 @article{van herk_gower_bronson_tanner_2011, title={Effects of climate warming on canopy water dynamics of a boreal black spruce plantation}, volume={41}, ISSN={["1208-6037"]}, DOI={10.1139/x10-196}, abstractNote={ The purpose of this study was to quantify the effects of climate change (in the form of elevated air and soil temperatures) on transpiration and sap flux rates of black spruce ( Picea mariana (Mill.) BSP). Five treatments were established in northern Manitoba, Canada, with the experimental design consisting of heated and control blocks. Air and soil temperatures were maintained approximately 5 °C above control temperatures using greenhouse chambers. Two of the chambers also included controls to maintain ambient vapor pressure difference (VPD). Sap flux (JS), was not significantly different among treatments in the May or July time periods. However, JS was significantly greater for heated VPD controlled trees than for trees in all other treatments when averaged over the entire study period. JS was positively correlated to photosynthetic photon flux density for all trees. Lower photosynthetic photon flux density in chamber treatments resulted in the creation of models used to estimate JS and canopy transpiration (EC) values that were used in the analysis. Average daily and cumulative growing season EC values were significantly greater for the heated VPD controlled treatments than for other treatments. The results from this study suggest that EC of boreal black spruce will increase if VPD remains unchanged while air temperatures increase. }, number={2}, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={Van Herk, Ingrid G. and Gower, Stith T. and Bronson, Dustin R. and Tanner, Myron S.}, year={2011}, month={Feb}, pages={217–227} }
 @article{bond-lamberty_gower_amiro_ewers_2011, title={Measurement and modelling of bryophyte evaporation in a boreal forest chronosequence}, volume={4}, ISSN={["1936-0592"]}, DOI={10.1002/eco.118}, abstractNote={Abstract}, number={1}, journal={ECOHYDROLOGY}, author={Bond-Lamberty, Ben and Gower, Stith T. and Amiro, Brian and Ewers, Brent E.}, year={2011}, month={Jan}, pages={26–35} }
 @article{peckham_gower_2011, title={Simulated long-term effects of harvest and biomass residue removal on soil carbon and nitrogen content and productivity for two Upper Great Lakes forest ecosystems}, volume={3}, ISSN={["1757-1707"]}, DOI={10.1111/j.1757-1707.2010.01067.x}, abstractNote={We used the ecosystem process model Biome‐BGC to simulate the effects of harvest and residue removal management scenarios on soil carbon (C), available soil nitrogen (N), net primary production (NPP), and net ecosystem production (NEP) in jack pine (Pinus banksiana Lamb.) and sugar maple (Acer saccharum Marsh) ecosystems in northern Wisconsin, USA. To assess harvest effects, we simulated short (50‐year) and long (100‐year) harvest intervals, high (clear‐cut) and low (selective) harvest intensities, and three levels of residue retention (15%, 25%, and 35%) over a 500‐year period. The model simulation of NPP, soil C accumulation, and NEP agreed reasonably well with biometric and eddy‐covariance measurements of these two ecosystems. The more intensive (50‐year rotation clear‐cuts with low residue retention) harvest scenarios tended to have the greatest NEP (420 and 678 t C ha−1 for the 500‐year interval for jack pine and sugar maple, respectively). All the harvest scenarios decreased mineral soil C and available mineral soil N content relative to the no‐harvest scenario for jack pine and sugar maple. The rate of change in mineral soil C decreased the greatest in the most intensive biomass removal scenarios (−0.012 and −0.072 t C ha−1 yr−1 relative to no‐harvest for jack pine and sugar maple, respectively) and the smallest decrease was observed in the least intensive biomass removal scenarios (−0.002 and −0.009 t C ha−1 yr−1 relative to no‐harvest for jack pine and sugar maple, respectively). The more intensive biomass removal harvest scenarios in sugar maple significantly decreased peak productivity (NPP) in the simulation period.}, number={2}, journal={GLOBAL CHANGE BIOLOGY BIOENERGY}, author={Peckham, Scott D. and Gower, Stith T.}, year={2011}, month={Apr}, pages={135–147} }
 @article{bronson_gower_2010, title={Ecosystem warming does not affect photosynthesis or aboveground autotrophic respiration for boreal black spruce}, volume={30}, ISSN={["0829-318X"]}, DOI={10.1093/treephys/tpq001}, abstractNote={We measured light-saturated photosynthesis (A(net)), foliage respiration (R(fol)) and stem respiration (R(stem)) of black spruce (Picea mariana (Mill.) B.S.P.) in heated (+5 degrees C) and control plots during 2005, 2006 and 2007 in Thompson, MB, Canada. Large greenhouses and soil-heating cables were used to maintain air and soil temperature 5 degrees C above ambient air and soil temperature. Each greenhouse contained approximately nine black spruce trees and the majority of their fine root mass. Treatments were soil and air warming, soil-only warming, greenhouses maintained at ambient air temperature and control. Gas exchange rates ranged 0.71-4.66, 0.04-0.74 and 0.1-1.0 micromol m(-)(2) s(-)(1) for A(net), R(fol) and R(stem), respectively. Treatment differences for A(net), R(fol) and R(stem) were not significant in any of the 3 years of measurements. The results of this experiment suggest that in a warmer climate, black spruce may not have significant changes in the rate of photosynthesis or respiration.}, number={4}, journal={TREE PHYSIOLOGY}, author={Bronson, Dustin R. and Gower, Stith T.}, year={2010}, month={Apr}, pages={441–449} }
 @article{dyer_gower_forrester_lorimer_mladenoff_burton_2010, title={Effects of selective tree harvests on aboveground biomass and net primary productivity of a second-growth northern hardwood forest}, volume={40}, ISSN={["1208-6037"]}, DOI={10.1139/x10-184}, abstractNote={Restoring structural features of old-growth forests, such as increased canopy gap sizes and coarse woody debris, is a common management goal for second-growth, even-aged stands. We experimentally manipulated forest structure by creating variable-size canopy gaps in a second-growth northern hardwood forest in north-central Wisconsin following two growing seasons of pre-treatment monitoring. The objectives of this study were to quantify the influence of canopy gaps of different sizes (50–380 m2) on aboveground biomass and productivity of each vegetation stratum two growing seasons following treatment. Two years after treatment, ground layer biomass in canopy openings increased significantly relative to surrounding undisturbed transition zones. The response of ground layer biomass was greatest in the large versus the medium and small gaps. Sapling aboveground net primary productivity was significantly greater in undisturbed transition zones than within gaps across gap sizes following the second post-treatment growing season. Annual stem diameter increment was greatest for trees along gap borders and was correlated with crown class, percentage of crown perimeter exposed, gap area, and shade tolerance. Total aboveground net primary productivity was significantly lower in the gap addition plots the first year but by the second post-treatment growing season no longer differed from that in the control plots.}, number={12}, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={Dyer, Jacob H. and Gower, Stith T. and Forrester, Jodi A. and Lorimer, Craig G. and Mladenoff, David J. and Burton, Julia I.}, year={2010}, month={Dec}, pages={2360–2369} }
 @article{stoffel_gower_forrester_mladenoff_2010, title={Effects of winter selective tree harvest on soil microclimate and surface CO2 flux of a northern hardwood forest}, volume={259}, ISSN={["0378-1127"]}, DOI={10.1016/j.foreco.2009.10.004}, abstractNote={Soil surface CO2 flux (Sflux) is the second largest terrestrial ecosystem carbon flux, and may be affected by forest harvest. The effects of clearcutting on Sflux have been studied, but little is known about the effect of alternative harvesting methods such as selective tree harvest on Sflux. We measured Sflux before and after (i) the creation of forest canopy gaps (simulating group tree selection harvests) and (ii) mechanized winter harvest but no tree removal (simulating ground disturbance associated with logging). The experiment was carried out in a sugar maple dominated forest in the Flambeau River State Forest, Wisconsin. Pre-treatment measurements of soil moisture, temperature and Sflux were measured throughout the growing season of 2006. In January–February 2007, a harvester created the canopy gaps (200–380 m2). The mechanization treatment consisted of the harvester traveling through the plots for a similar amount of time as the gap plots, but no trees were cut. Soil moisture and temperature and Sflux were measured throughout the growing season for 1 year prior to harvest and for 2 years after harvest. Soil moisture and temperature were significantly greater in the gap than mechanized and control treatments. Instantaneous Sflux was positively correlated to soil moisture and soil temperature at 2 and 10 cm, but temperature at 10 cm was the single best predictor. Annual Sflux was not significantly different among treatments prior to winter 2007 harvest, and was not significantly different among treatments after harvest. Annual (+1 std. err.) Sflux averaged 967 + 72, 1011 + 72, and 1012 + 72 g C m−2 year−1 in the control, mechanized and gap treatments, respectively, for the 2-year post-treatment period. The results from this study suggest selective group tree harvest significantly increases soil moisture and temperature but does not significantly influence Sflux.}, number={3}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Stoffel, Jennifer L. and Gower, Stith T. and Forrester, Jodi A. and Mladenoff, David J.}, year={2010}, month={Jan}, pages={257–265} }
 @article{peckham_ahl_gower_2009, title={Bryophyte cover estimation in a boreal black spruce forest using airborne lidar and multispectral sensors}, volume={113}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2009.02.008}, abstractNote={Bryophytes are the dominant ground cover vegetation layer in many boreal forests and in some of these forests the net primary production of bryophytes exceeds the overstory. Therefore it is necessary to quantify their spatial coverage and species composition in boreal forests to improve boreal forest carbon budget estimates. We present results from a small exploratory test using airborne lidar and multispectral remote sensing data to estimate the percentage of ground cover for mosses in a boreal black spruce forest in Manitoba, Canada. Multiple linear regression was used to fit models that combined spectral reflectance data from CASI and indices computed from the SLICER canopy height profile. Three models explained 63–79% of the measured variation of feathermoss cover while three models explained 69–92% of the measured variation of sphagnum cover. Root mean square errors ranged from 3–15% when predicting feathermoss, sphagnum, and total moss ground cover. The results from this case study warrant further testing for a wider range of boreal forest types and geographic regions.}, number={6}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Peckham, Scott D. and Ahl, Douglas E. and Gower, Stith T.}, year={2009}, month={Jun}, pages={1127–1132} }
 @misc{serbin_gower_ahl_2009, title={Canopy dynamics and phenology of a boreal black spruce wildfire chronosequence}, volume={149}, ISSN={["1873-2240"]}, DOI={10.1016/j.agrformet.2008.08.001}, abstractNote={This research quantified the canopy phenology, growing season and inter-annual dynamics of the overstory and understory vegetation in a boreal wildfire chronosequence in northern Manitoba, Canada. Optical measurements of the canopy radiation regime were made in the 2004–2006 growing seasons to evaluate the spatial and temporal variation in the effective leaf area index (Le) and fraction of intercepted photosynthetic active radiation (FIPAR) of the canopy. Black spruce dominated the overstory Le (LeO) in the oldest stands (74- and 154-year-old), while deciduous shrub and tree species dominated the youngest stands (1- to 23-year-old). LeO varied from a minimum (mean ± S.D.) of 0.26 ± 0.33 to a maximum of 2.33 ± 1.20 and from 0.63 ± 0.56 to 1.20 ± 0.56 for the understory vegetation (LeU). FIPARO was negligible in the youngest stands, and reached a peak in the oldest stands studied. LeU comprised a significant percentage of total Le (>30%) and FIPAR (>20%) for all stands, except the oldest, 154-year-old stand. We observed two key features in the Le and FIPAR seasonal cycles: (i) significant changes (p < 0.001) in LeU, increasing by 41% across all sites; and (ii) >80% difference in seasonality exhibited by the overstory in the mixed/deciduous and black spruce dominated stands. Le varied by less than 20% among the three years. Canopy green-up was positively correlated to spring temperatures and occurred within 20–28 days for all stands. The pronounced increase in wildfires in the boreal forest in recent years necessitates additional studies to better understand their effects on the species composition and structure of canopies of all vegetation strata.}, number={1}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Serbin, Shawn P. and Gower, Stith T. and Ahl, Douglas E.}, year={2009}, month={Jan}, pages={187–204} }
 @article{bronson_gower_tanner_van herk_2009, title={Effect of ecosystem warming on boreal black spruce bud burst and shoot growth}, volume={15}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2009.01845.x}, abstractNote={Abstract}, number={6}, journal={GLOBAL CHANGE BIOLOGY}, author={Bronson, Dustin R. and Gower, Stith T. and Tanner, Myron and Van Herk, Ingrid}, year={2009}, month={Jun}, pages={1534–1543} }
 @article{bond-lamberty_peckham_gower_ewers_2009, title={Effects of fire on regional evapotranspiration in the central Canadian boreal forest}, volume={15}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2008.01776.x}, abstractNote={Abstract}, number={5}, journal={GLOBAL CHANGE BIOLOGY}, author={Bond-Lamberty, Ben and Peckham, Scott D. and Gower, Stith T. and Ewers, Brent E.}, year={2009}, month={May}, pages={1242–1254} }
 @article{gower_2008, title={Are horses responsible for introducing non-native plants along forest trails in the eastern United States?}, volume={256}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2008.06.012}, abstractNote={Non-native plant species pose a serious ecological and economic threat to managed and natural ecosystems; therefore, there is a great need to identify sources for the introduction of non-native species and develop management plans to reduce or eliminate their introduction. Horses have been suggested to be an important source for the introduction of non-native plant species along trails, but the conclusions were based on anecdotal evidence. In this study, horse hay, manure, and hoof debris samples were collected from 12 to 24 horses at five endurance ride events in North Carolina, Kentucky, Illinois, Wisconsin, and Michigan. One sub-sample of each material from each horse was sown in pots and grown under ideal conditions to determine if horse hay, manure, and hoof debris samples contained seeds from non-native species. A second sub-sample of each material from each horse was placed back on their respective trail to determine what plants would germinate and establish on the trail. Vegetation surveys were also conducted along 50 m transects perpendicular to horse and hiking (horses not permitted) trails at three of the five sites to compare species composition of native and non-native plant species. On average, non-native plant species germinated in 5.2% of the hay samples in the pots, but non-native species did not germinate from the manure or hoof debris samples. Only 3 of the 288 (≈1% of total samples) hay, manure, and hoof debris plots established on horse trails at the five sites contained plants, all of which were native plants, at the end of the first growing season and no plants were observed at the end of the second growing season. Non-native species composition and percent of total plants species did not differ significantly (p = 0.56) between horse and non-horse trails, and non-native plant species were only found within 2 m of the trail. The results of this and another study [Campbell, J.E., Gibson, D.J., 2001. The effect of seeds of exotic species transported vie horse dung on vegetation along trail corridors. Plant Ecology 157, 23–35] demonstrate that horse hay and manure does contain seeds of non-native plant species, but native and non-native plant species rarely become established on horse trails because of the harsh environmental conditions. Management and policy implication of this study are discussed.}, number={5}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Gower, Stith T.}, year={2008}, month={Aug}, pages={997–1003} }
 @article{vogel_bond-lamberty_schuur_gower_mack_kari e. b. o'connell_valentine_ruess_2008, title={Carbon allocation in boreal black spruce forests across regions varying in soil temperature and precipitation}, volume={14}, ISSN={["1354-1013"]}, DOI={10.1111/j.1365-2486.2008.01600.x}, abstractNote={Abstract}, number={7}, journal={GLOBAL CHANGE BIOLOGY}, author={Vogel, Jason G. and Bond-Lamberty, Ben P. and Schuur, Edward A. G. and Gower, Stith T. and Mack, Michelle C. and Kari E. B. O'Connell and Valentine, David W. and Ruess, Roger W.}, year={2008}, month={Jul}, pages={1503–1516} }
 @article{bond-lamberty_gower_2008, title={Decomposition and fragmentation of coarse woody debris: Re-visiting a boreal black spruce chronosequence}, volume={11}, ISSN={["1435-0629"]}, DOI={10.1007/s10021-008-9163-y}, number={6}, journal={ECOSYSTEMS}, author={Bond-Lamberty, Ben and Gower, Stith T.}, year={2008}, month={Sep}, pages={831–840} }
 @article{peckham_ahl_serbin_gower_2008, title={Fire-induced changes in green-up and leaf maturity of the Canadian boreal forest}, volume={112}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2008.04.016}, abstractNote={Recent studies of vegetation phenology of northern forests using satellite data suggest that the observed earlier spring increase and peak amplitude of the normalized difference vegetation index (NDVI) are a result of climate warming. In addition to undergoing an increase in temperature, the northern forests of Canada have also seen a dramatic increase in area burned by wildfire over the same time period. Using the Canadian Large Fire Database, we analyzed the impact fire had on the phenological dates derived from fitting a logistical model to yearly data from 2004 for several different subsets of both AVHRR-NDVI and MODIS LAI in wildfire dominated terrestrial ecozones. Fire had a significant but complex effect on estimated phenology dates. The most recently burned areas (1994–2003) had later green-up dates in two ecozones for AVHRR data and all ecozones for MODIS. However, older forested (not burned during 1980–2003) had estimated green-up dates 1 to 9 days earlier than the entire forested area in the MODIS LAI data. These data corroborate studies in Canada and demonstrate that fire history is influencing boreal forest phenology and growing season LAI.}, number={9}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Peckham, Scott D. and Ahl, Douglas E. and Serbin, Shawn P. and Gower, Stith T.}, year={2008}, month={Sep}, pages={3594–3603} }
 @article{bronson_gower_tanner_linder_van herk_2008, title={Response of soil surface CO2 flux in a boreal forest to ecosystem warming}, volume={14}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2007.01508.x}, abstractNote={Abstract}, number={4}, journal={GLOBAL CHANGE BIOLOGY}, author={Bronson, Dustin R. and Gower, Stith T. and Tanner, Myron and Linder, Sune and Van Herk, Ingrid}, year={2008}, month={Apr}, pages={856–867} }
 @article{bond-lamberty_gower_2007, title={Estimation of stand-level leaf area for boreal bryophytes}, volume={151}, ISSN={["1432-1939"]}, DOI={10.1007/s00442-006-0619-5}, abstractNote={Bryophytes dominate the carbon and nitrogen cycling of many poorly drained terrestrial ecosystems and are important in the vegetation-atmosphere exchange of carbon and water, yet few studies have estimated their leaf area at the stand scale. This study quantified the bryophyte-specific leaf area (SLA) and leaf area index (LAI) in a group of different-aged boreal forest stands in well and poorly drained soils. Species-specific SLA (for three feather mosses, four Sphagnum spp. and Aulacomnium palustre mixed with Tomentypnum nitens) was assessed by determining the projected area using a flatbed scanner and cross-sectional geometry using a dissecting microscope. The hemisurface leaf area was computed as the product of SLA and live biomass and was scaled by coverage data collected at all stands. Pleurozium schreberi dominated the spatial coverage, biomass and leaf area in the well-drained stands, particularly the oldest, while S. fuscum and A. palustre were important in the poorly drained stands. Live moss biomass ranged from 47 to 230 g m(-2) in the well-drained stands dominated by feather mosses and from 102 to 228 g m(-2) in the poorly drained stands. Bryophyte SLA varied between 135 and 473 cm(2) g(-1), for A. palustre and S. capillifolium, respectively. SLA was strongly and significantly affected by bryophyte species, but did not vary between stands; in general, there was no significant difference between the SLA of non-Sphagnum mosses. Bryophyte LAI increased with stand age, peaking at 3.1 and 3.7 in the well and poorly drained stands, respectively; this represented approximately 40% of the overstory LAI in the well-drained stands and 100-1,000% in the poorly drained stands, underscoring the important role bryophytes play in the water and carbon budgets of these boreal forests.}, number={4}, journal={OECOLOGIA}, author={Bond-Lamberty, Ben and Gower, Stith T.}, year={2007}, month={Apr}, pages={584–592} }
 @article{bond-lamberty_peckham_ahl_gower_2007, title={Fire as the dominant driver of central Canadian boreal forest carbon balance}, volume={450}, ISSN={["1476-4687"]}, DOI={10.1038/nature06272}, abstractNote={Changes in climate, atmospheric carbon dioxide concentration and fire regimes have been occurring for decades in the global boreal forest, with future climate change likely to increase fire frequency--the primary disturbance agent in most boreal forests. Previous attempts to assess quantitatively the effect of changing environmental conditions on the net boreal forest carbon balance have not taken into account the competition between different vegetation types on a large scale. Here we use a process model with three competing vascular and non-vascular vegetation types to examine the effects of climate, carbon dioxide concentrations and fire disturbance on net biome production, net primary production and vegetation dominance in 100 Mha of Canadian boreal forest. We find that the carbon balance of this region was driven by changes in fire disturbance from 1948 to 2005. Climate changes affected the variability, but not the mean, of the landscape carbon balance, with precipitation exerting a more significant effect than temperature. We show that more frequent and larger fires in the late twentieth century resulted in deciduous trees and mosses increasing production at the expense of coniferous trees. Our model did not however exhibit the increases in total forest net primary production that have been inferred from satellite data. We find that poor soil drainage decreased the variability of the landscape carbon balance, which suggests that increased climate and hydrological changes have the potential to affect disproportionately the carbon dynamics of these areas. Overall, we conclude that direct ecophysiological changes resulting from global climate change have not yet been felt in this large boreal region. Variations in the landscape carbon balance and vegetation dominance have so far been driven largely by increases in fire frequency.}, number={7166}, journal={NATURE}, author={Bond-Lamberty, Ben and Peckham, Scott D. and Ahl, Douglas E. and Gower, Stith T.}, year={2007}, month={Nov}, pages={89-+} }
 @article{bond-lamberty_gower_ahl_2007, title={Improved simulation of poorly drained forests using Biome-BGC}, volume={27}, ISSN={["1758-4469"]}, DOI={10.1093/treephys/27.5.703}, abstractNote={Forested wetlands and peatlands are important in boreal and terrestrial biogeochemical cycling, but most general-purpose forest process models are designed and parameterized for upland systems. We describe changes made to Biome-BGC, an ecophysiological process model, that improve its ability to simulate poorly drained forests. Model changes allowed for: (1) lateral water inflow from a surrounding watershed, and variable surface and subsurface drainage; (2) adverse effects of anoxic soil on decomposition and nutrient mineralization; (3) closure of leaf stomata in flooded soils; and (4) growth of nonvascular plants (i.e., bryophytes). Bryophytes were treated as ectohydric broadleaf evergreen plants with zero stomatal conductance, whose cuticular conductance to CO(2) was dependent on plant water content. Individual model changes were parameterized with published data, and ecosystem-level model performance was assessed by comparing simulated output to field data from the northern BOREAS site in Manitoba, Canada. The simulation of the poorly drained forest model exhibited reduced decomposition and vascular plant growth (-90%) compared with that of the well-drained forest model; the integrated bryophyte photosynthetic response accorded well with published data. Simulated net primary production, biomass and soil carbon accumulation broadly agreed with field measurements, although simulated net primary production was higher than observed data in well-drained stands. Simulated net primary production in the poorly drained forest was most sensitive to oxygen restriction on soil processes, and secondarily to stomatal closure in flooded conditions. The modified Biome-BGC remains unable to simulate true wetlands that are subject to prolonged flooding, because it does not track organic soil formation, water table changes, soil redox potential or anaerobic processes.}, number={5}, journal={TREE PHYSIOLOGY}, author={Bond-Lamberty, Ben and Gower, Stith T. and Ahl, Douglas E.}, year={2007}, month={May}, pages={703–715} }
 @article{martin_gower_2006, title={Boreal mixedwood tree growth on contrasting soils and disturbance types}, volume={36}, ISSN={["1208-6037"]}, DOI={10.1139/x05-306}, abstractNote={Mixedwood forests are an ecologically and economically important ecosystem in the boreal forest of northern Canada. The objectives of this study were to (i) compare the age–height relationships for dominant tree species growing on two contrasting soil types and originating from different disturbances (logging versus wildfire), and (ii) determine the influence of competition on tree growth. Eight stands were selected that encompassed two age-classes replicated on two soil types (clay loam and sand) in a split-plot design. Four of the eight stands originated from logging (21–26 years old), and <F"Times">the four others originated from wildfires (80 years old). Nonlinear age–height analyses were used to compare annual height and radial increment growth of black spruce (Picea mariana (Mill.) BSP), jack pine (Pinus banksiana Lamb.), and trembling aspen (Populus tremuloides Michx.). Species, soil type, and size class explained significant amounts of the measured variation in the age–height models. Aspen, black spruce, and jack pine were 16%, 27%, and 19% taller, respectively, on clay soils than on sandy soils at the burned stand. Tree heights did not differ significantly among species or between soil types in logged stands. Diameter growth decreased as competition increased for black spruce and jack pine in the burned stands. The results for these three important boreal tree species are discussed in the context of sustainable forestry for boreal mixedwood forests.}, number={4}, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={Martin, Jennifer L. and Gower, Stith T.}, year={2006}, month={Apr}, pages={986–995} }
 @article{turner_ritts_cohen_gower_running_zhao_costa_kirschbaum_ham_saleska_et al._2006, title={Evaluation of MODIS NPP and GPP products across multiple biomes}, volume={102}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2006.02.017}, abstractNote={Estimates of daily gross primary production (GPP) and annual net primary production (NPP) at the 1 km spatial resolution are now produced operationally for the global terrestrial surface using imagery from the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor. Ecosystem-level measurements of GPP at eddy covariance flux towers and plot-level measurements of NPP over the surrounding landscape offer opportunities for validating the MODIS NPP and GPP products, but these flux measurements must be scaled over areas on the order of 25 km2 to make effective comparisons to the MODIS products. Here, we report results for such comparisons at 9 sites varying widely in biome type and land use. The sites included arctic tundra, boreal forest, temperate hardwood forest, temperate conifer forest, tropical rain forest, tallgrass prairie, desert grassland, and cropland. The ground-based NPP and GPP surfaces were generated by application of the Biome-BGC carbon cycle process model in a spatially-distributed mode. Model inputs of land cover and leaf area index were derived from Landsat data. The MODIS NPP and GPP products showed no overall bias. They tended to be overestimates at low productivity sites — often because of artificially high values of MODIS FPAR (fraction of photosynthetically active radiation absorbed by the canopy), a critical input to the MODIS GPP algorithm. In contrast, the MODIS products tended to be underestimates in high productivity sites — often a function of relatively low values for vegetation light use efficiency in the MODIS GPP algorithm. A global network of sites where both NPP and GPP are measured and scaled over the local landscape is needed to more comprehensively validate the MODIS NPP and GPP products and to potentially calibrate the MODIS NPP/GPP algorithm parameters.}, number={3-4}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Turner, David P. and Ritts, William D. and Cohen, Warren B. and Gower, Stith T. and Running, Steve W. and Zhao, Maosheng and Costa, Marcos H. and Kirschbaum, Al A. and Ham, Jay M. and Saleska, Scott R. and et al.}, year={2006}, month={Jun}, pages={282–292} }
 @article{cohen_maiersperger_turner_ritts_pflugmacher_kennedy_kirschbaum_running_costa_gower_2006, title={MODIS land cover and LAI collection 4 product quality across nine sites in the western hemisphere}, volume={44}, ISSN={["1558-0644"]}, DOI={10.1109/tgrs.2006.876026}, abstractNote={Global maps of land cover and leaf area index (LAI) derived from the Moderate Resolution Imaging Spectrometer (MODIS) reflectance data are an important resource in studies of global change, but errors in these must be characterized and well understood. Product validation requires careful scaling from ground and related measurements to a grain commensurate with MODIS products. We present an updated BigFoot project protocol for developing 25-m validation data layers over 49-km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 </sup> study areas. Results from comparisons of MODIS and BigFoot land cover and LAI products at nine contrasting sites are reported. In terms of proportional coverage, MODIS and BigFoot land cover were in close agreement at six sites. The largest differences were at low tree cover evergreen needleleaf sites and at an Arctic tundra site where the MODIS product overestimated woody cover proportions. At low leaf biomass sites there was reasonable agreement between MODIS and BigFoot LAI products, but there was not a particular MODIS LAI algorithm pathway that consistently compared most favorably. At high leaf biomass sites, MODIS LAI was generally overpredicted by a significant amount. For evergreen needleleaf sites, LAI seasonality was exaggerated by MODIS. Our results suggest incremental improvement from Collection 3 to Collection 4 MODIS products, with some remaining problems that need to be addressed}, number={7}, journal={IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING}, author={Cohen, Warren B. and Maiersperger, Thomas K. and Turner, David P. and Ritts, William D. and Pflugmacher, Dirk and Kennedy, Robert E. and Kirschbaum, Alan and Running, Steven W. and Costa, Marcos and Gower, Stith T.}, year={2006}, month={Jul}, pages={1843–1857} }
 @article{yang_tan_huang_rautiainen_shabanov_wang_privette_huemmrich_fensholt_sandholt_et al._2006, title={MODIS leaf area index products: From validation to algorithm improvement}, volume={44}, DOI={10.1109/tgrs.2006.871215}, abstractNote={Global products of vegetation green Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) are being operationally produced from Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) at 1-km resolution and eight-day frequency. This paper summarizes the experience of several collaborating investigators on validation of MODIS LAI products and demonstrates the close connection between product validation and algorithm refinement activities. The validation of moderate resolution LAI products includes three steps: 1) field sampling representative of LAI spatial distribution and dynamic range within each major land cover type at the validation site; 2) development of a transfer function between field LAI measurements and high resolution satellite data to generate a reference LAI map over an extended area; and 3) comparison of MODIS LAI with aggregated reference LAI map at patch (multipixel) scale in view of geo-location and pixel shift uncertainties. The MODIS LAI validation experiences, summarized here, suggest three key factors that influence the accuracy of LAI retrievals: 1) uncertainties in input land cover data, 2) uncertainties in input surface reflectances, and 3) uncertainties from the model used to build the look-up tables accompanying the algorithm. This strategy of validation efforts guiding algorithm refinements has led to progressively more accurate LAI products from the MODIS sensors aboard NASA's Terra and Aqua platforms}, number={7}, journal={IEEE Transactions on Geoscience and Remote Sensing}, author={Yang, W. Z. and Tan, B. and Huang, D. and Rautiainen, M. and Shabanov, N. V. and Wang, Y. and Privette, J. L. and Huemmrich, K. F. and Fensholt, R. and Sandholt, I. and et al.}, year={2006}, pages={1885–1898} }
 @article{ahl_gower_burrows_shabanov_myneni_knyazikhin_2006, title={Monitoring spring canopy phenology of a deciduous broadleaf forest using MODIS}, volume={104}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2006.05.003}, abstractNote={Climate change is predicted to alter the canopy phenology of temperate and boreal forests, which will affect carbon, water, and energy budgets. Therefore, there is a great need to evaluate remotely sensed products for their potential to accurately capture canopy dynamics. The objective of this study was to compare several products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) to field measurements of fraction photosynthetically active radiation (FPAR) and plant area index (PAI) for a deciduous broadleaf forest in northern Wisconsin in 2002. MODIS products captured the general phenological development of the canopy although MODIS products overestimated the leaf area during the overstory leaf out period. Field data suggest that the period from budburst to canopy maturity, or maximum PAI, occurred in 10 to 12 days while MODIS products predicted onset of greenness and maturity from 1 to 21 days and 0 to 19 days earlier than that from field observations, respectively. Temporal compositing of MODIS data and understory development are likely key factors explaining differences with field data. Maximum PAI estimates differed only by 7% between field derived and MODIS-based estimates of LAI. Implications for ecosystem modeling of carbon and water exchange and future research needs are discussed.}, number={1}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Ahl, Douglas E. and Gower, Stith T. and Burrows, Sean N. and Shabanov, Nikolay V. and Myneni, Ranga B. and Knyazikhin, Yuri}, year={2006}, month={Sep}, pages={88–95} }
 @article{bond-lamberty_gower_wang_cyr_veldhuis_2006, title={Nitrogen dynamics of a boreal black spruce wildfire chronosequence}, volume={81}, ISSN={["1573-515X"]}, DOI={10.1007/s10533-006-9025-7}, number={1}, journal={BIOGEOCHEMISTRY}, author={Bond-Lamberty, Ben and Gower, Stith T. and Wang, Chuankuan and Cyr, Pascal and Veldhuis, Hugo}, year={2006}, month={Oct}, pages={1–16} }
 @article{bond-lamberty_gower_goulden_mcmillan_2006, title={Simulation of boreal black spruce chronosequences: Comparison to field measurements and model evaluation}, volume={111}, ISSN={["2169-8961"]}, DOI={10.1029/2005jg000123}, abstractNote={This study used the Biome Biogeochemical Cycles (Biome‐BGC) process model to simulate boreal forest dynamics, compared the results with a variety of measured carbon content and flux data from two boreal chronosequences in northern Manitoba, Canada, and examined how model output was affected by water and nitrogen limitations on simulated plant production and decomposition. Vascular and nonvascular plant growth were modeled over 151 years in well‐drained and poorly drained forests, using as many site‐specific model parameters as possible. Measured data included (1) leaf area and carbon content from site‐specific allometry data, (2) aboveground and belowground net primary production from allometry and root cores, and (3) flux data, including biometry‐based net ecosystem production and tower‐based net ecosystem exchange. The simulation used three vegetation types or functional groups (evergreen needleaf trees, deciduous broadleaf trees, and bryophytes). Model output matched some of the observed data well, with net primary production, biomass, and net ecosystem production (NEP) values usually (50–80% of data) within the errors of observed values. Leaf area was generally underpredicted. In the simulation, nitrogen limitation increased with stand age, while soil anoxia limited vascular plant growth in the poorly drained simulation. NEP was most sensitive to climate variability in the poorly drained stands. Simulation results are discussed with respect to conceptual issues in, and parameterization of, the Biome‐BGC model.}, number={G2}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES}, author={Bond-Lamberty, Ben and Gower, Stith T. and Goulden, Michael L. and McMillan, Andrew}, year={2006}, month={Jun} }
 @article{bond-lamberty_brown_goranson_gower_2006, title={Spatial dynamics of soil moisture and temperature in a black spruce boreal chronosequence}, volume={36}, ISSN={["1208-6037"]}, DOI={10.1139/x06-160}, abstractNote={ This study analyzed the spatial dependencies of soil moisture and temperature in a six-stand chronosequence of boreal black spruce (Picea mariana (Mill.) BSP) stands. Spatial variability of soil temperature (TSOIL) was evaluated twice during the growing season using four transects in each stand, employing a cyclic sampling design with measurements spaced 2–92 m apart. Soil moisture (θg) was measured on one occasion. A spherical model was used to analyze the geostatistical correlation structure; θg and TSOIL at the 7- and 21-year-old stands did not exhibit stable ranges or sills. The fits with stable ranges and sills modeled the spatial patterns in the older stands reasonably well, although unexplained variability was high. Calculated ranges varied from 3 to 150 m for these stands, lengths probably related to structural characteristics influential in local-scale energy transfer. Transect-to-transect variability was significant and typically 5%–15% of the mean for TSOIL and 10%–70% for θg. TSOIL and θg were negatively correlated for most stands and depths, with TSOIL dropping 0.5–0.9 °C for every 1% rise in θg. The results reported here provide initial data to assess the spatial variability of TSOIL and θg in a variety of boreal forest stand ages. }, number={11}, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={Bond-Lamberty, Ben and Brown, Karen M. and Goranson, Carol and Gower, Stith T.}, year={2006}, month={Nov}, pages={2794–2802} }
 @article{shabanov_huang_yang_tan_knyazikhin_myneni_ahl_gower_huete_aragao_et al._2005, title={Analysis and optimization of the MODIS leaf area index algorithm retrievals over broadleaf forests}, volume={43}, ISSN={["1558-0644"]}, DOI={10.1109/tgrs.2005.852477}, abstractNote={Broadleaf forest is a major type of Earth's land cover with the highest observable vegetation density. Retrievals of biophysical parameters, such as leaf area index (LAI), of broadleaf forests at global scale constitute a major challenge to modern remote sensing techniques in view of low sensitivity (saturation) of surface reflectances to such parameters over dense vegetation. The goal of the performed research is to demonstrate physical principles of LAI retrievals over broadleaf forests with the Moderate Resolution Imaging Spectroradiometer (MODIS) LAI algorithm and to establish a basis for algorithm refinement. To sample natural variability in biophysical parameters of broadleaf forests, we selected MODIS data subsets covering deciduous broadleaf forests of the eastern part of North America and evergreen broadleaf forests of Amazonia. The analysis of an annual course of the Terra MODIS Collection 4 LAI product over broadleaf forests indicated a low portion of best quality main radiative transfer-based algorithm retrievals and dominance of low-reliable backup algorithm retrievals during the growing season. We found that this retrieval anomaly was due to an inconsistency between simulated and MODIS surface reflectances. LAI retrievals over dense vegetation are mostly performed over a compact location in the spectral space of saturated surface reflectances, which need to be accurately modeled. New simulations were performed with the stochastic radiative transfer model, which poses high numerical accuracy at the condition of saturation. Separate sets of parameters of the LAI algorithm were generated for deciduous and evergreen broadleaf forests to account for the differences in the corresponding surface reflectance properties. The optimized algorithm closely captures physics of seasonal variations in surface reflectances and delivers a majority of LAI retrievals during a phenological cycle, consistent with field measurements. The analysis of the optimized retrievals indicates that the precision of MODIS surface reflectances, the natural variability, and mixture of species set a limit to improvements of the accuracy of LAI retrievals over broadleaf forests.}, number={8}, journal={IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING}, author={Shabanov, NV and Huang, D and Yang, WZ and Tan, B and Knyazikhin, Y and Myneni, RB and Ahl, DE and Gower, ST and Huete, AR and Aragao, LEOC and et al.}, year={2005}, month={Aug}, pages={1855–1865} }
 @article{martin_gower_plaut_holmes_2005, title={Carbon pools in a boreal mixedwood logging chronosequence}, volume={11}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2005.01019.x}, abstractNote={Abstract}, number={11}, journal={GLOBAL CHANGE BIOLOGY}, author={Martin, JL and Gower, ST and Plaut, J and Holmes, B}, year={2005}, month={Nov}, pages={1883–1894} }
 @article{berterretche_hudak_cohen_maiersperger_gower_dungan_2005, title={Comparison of regression and geostatistical methods for mapping Leaf Area Index (LAI) with Landsat ETM+ data over a boreal forest}, volume={96}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2005.01.014}, abstractNote={This study compared aspatial and spatial methods of using remote sensing and field data to predict maximum growing season leaf area index (LAI) maps in a boreal forest in Manitoba, Canada. The methods tested were orthogonal regression analysis (reduced major axis, RMA) and two geostatistical techniques: kriging with an external drift (KED) and sequential Gaussian conditional simulation (SGCS). Deterministic methods such as RMA and KED provide a single predicted map with either aspatial (e.g., standard error, in regression techniques) or limited spatial (e.g., KED variance) assessments of errors, respectively. In contrast, SGCS takes a probabilistic approach, where simulated values are conditional on the sample values and preserve the sample statistics. In this application, canonical indices were used to maximize the ability of Landsat ETM+ spectral data to account for LAI variability measured in the field through a spatially nested sampling design. As expected based on theory, SGCS did the best job preserving the distribution of measured LAI values. In terms of spatial pattern, SGCS preserved the anisotropy observed in semivariograms of measured LAI, while KED reduced anisotropy and lowered global variance (i.e., lower sill), also consistent with theory. The conditional variance of multiple SGCS realizations provided a useful visual and quantitative measure of spatial uncertainty. For applications requiring spatial prediction methods, we concluded KED is more useful if local accuracy is important, but SGCS is better for indicating global pattern. Predicting LAI from satellite data using geostatistical methods requires a distribution and density of primary, reference LAI measurements that are impractical to obtain. For regional NPP modeling with coarse resolution inputs, the aspatial RMA regression method is the most practical option.}, number={1}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Berterretche, M and Hudak, AT and Cohen, WB and Maiersperger, TK and Gower, ST and Dungan, J}, year={2005}, month={May}, pages={49–61} }
 @article{wang_feldkirchner_gower_ferris_kruger_2005, title={Effects of amendments of paper mill sludge and nutrients on soil surface CO2 flux in northern hardwood forests}, volume={16}, DOI={10.1007/bf02858186}, number={4}, journal={Journal of Forestry Research}, author={Wang, C.K. and Feldkirchner, D. C. and Gower, S. T. and Ferris, J. and Kruger, E. L.}, year={2005}, pages={265–269} }
 @article{ewers_gower_bond-lamberty_wang_2005, title={Effects of stand age and tree species on canopy transpiration and average stomatal conductance of boreal forests}, volume={28}, ISSN={["1365-3040"]}, DOI={10.1111/j.1365-3040.2005.01312.x}, abstractNote={ABSTRACT}, number={5}, journal={PLANT CELL AND ENVIRONMENT}, author={Ewers, BE and Gower, ST and Bond-Lamberty, B and Wang, CK}, year={2005}, month={May}, pages={660–678} }
 @article{white_gower_ahl_2005, title={Life cycle inventories of roundwood production in northern Wisconsin: Inputs into an industrial forest carbon budget}, volume={219}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2005.08.039}, abstractNote={Carbon budgets are developed to understand ecosystem dynamics and are increasingly being used to develop global change policy. Traditionally, forest carbon budgets have focused on the biological carbon cycle; however, it is important to include the industrial forest carbon cycle as well. The overall objective of this study was to quantify the major carbon fluxes associated with the production of Wisconsin's industrial roundwood, by using life cycle inventory (LCI) methodology to produce an industrial forest carbon budget. To achieve this objective we (1) developed carbon LCIs for the harvest process for three major forest ownerships (state, national, and private non-industrial), (2) developed carbon LCIs for a dimensional lumber and two oriented strand board (OSB) mills and (3) completed a scaled version of 1 and 2 to include more Wisconsin forestlands and to incorporate the other major processes within the industrial forest carbon cycle (e.g. primary mill, secondary mill, product use and product disposal processes of the industrial forest carbon cycle). The carbon budgets for the harvesting process of the Chequamegon-Nicolet National Forest (CNNF), the Northern Highland American Legion State Forest (NHAL), and the non-industrial private forests that participated in the managed forest laws of Wisconsin (MFL-NIPF) were 0.10, 0.18 and 0.11 tonnes C ha−1 year−1), respectively. The dimensional lumber and OSB products were both net carbon sources, and released 0.05–0.09 tonnes C/tonnes C processed). More carbon is sequestered than released within the industrial forest carbon cycle of Wisconsin's national (6 g C m−2 year−1), state (12 g C m−2 year−1) and non-industrial private forests (7 g C m−2 year−1). Using published net ecosystem production data we estimate that the net forest carbon cycle budget (sum of the biological and industrial C cycle, [Gower, S.T., 2003. Patterns and mechanisms of the forest carbon cycle. Ann. Rev. Environ. Resour. 28, 169–204]) for the CNNF ranges between −897 and 348 g C m−2 year−1. Life cycle inventories of wood and paper products should be clear and explicitly state what processes are included, so that results can be used by policy makers and future researchers.}, number={1}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={White, MK and Gower, ST and Ahl, DE}, year={2005}, month={Nov}, pages={13–28} }
 @article{bond-lamberty_gower_ahl_thornton_2005, title={Reimplementation of the Biome-BGC model to simulate successional change}, volume={25}, ISSN={["1758-4469"]}, DOI={10.1093/treephys/25.4.413}, abstractNote={Biogeochemical process models are increasingly employed to simulate current and future forest dynamics, but most simulate only a single canopy type. This limitation means that mixed stands, canopy succession and understory dynamics cannot be modeled, severe handicaps in many forests. The goals of this study were to develop a version of Biome-BGC that supported multiple, interacting vegetation types, and to assess its performance and limitations by comparing modeled results to published data from a 150-year boreal black spruce (Picea mariana (Mill.) BSP) chronosequence in northern Manitoba, Canada. Model data structures and logic were modified to support an arbitrary number of interacting vegetation types; an explicit height calculation was necessary to prioritize radiation and precipitation interception. Two vegetation types, evergreen needle-leaf and deciduous broadleaf, were modeled based on site-specific meteorological and physiological data. The new version of Biome-BGC reliably simulated observed changes in leaf area, net primary production and carbon stocks, and should be useful for modeling the dynamics of mixed-species stands and ecological succession. We discuss the strengths and limitations of Biome-BGC for this application, and note areas in which further work is necessary for reliable simulation of boreal biogeochemical cycling at a landscape scale.}, number={4}, journal={TREE PHYSIOLOGY}, author={Bond-Lamberty, B and Gower, ST and Ahl, DE and Thornton, PE}, year={2005}, month={Apr}, pages={413–424} }
 @article{turner_ritts_cohen_maeirsperger_gower_kirschbaum_running_zhao_wofsy_dunn_et al._2005, title={Site-level evaluation of satellite-based global terrestrial gross primary production and net primary production monitoring}, volume={11}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2005.00936.x}, abstractNote={Abstract}, number={4}, journal={GLOBAL CHANGE BIOLOGY}, author={Turner, DP and Ritts, WD and Cohen, WB and Maeirsperger, TK and Gower, ST and Kirschbaum, AA and Running, SW and Zhao, MS and Wofsy, SC and Dunn, AL and et al.}, year={2005}, month={Apr}, pages={666–684} }
 @article{bond-lamberty_wang_gower_2005, title={Spatiotemporal measurement and modeling of stand-level boreal forest soil temperatures}, volume={131}, ISSN={["1873-2240"]}, DOI={10.1016/j.agrformet.2005.04.008}, abstractNote={The spatial and temporal dynamics of soil temperature (TSOIL) strongly influence a wide range of biotic and abiotic processes in boreal forests. Relatively few spatial and temporal TSOIL measurements have been made in these systems; in addition, not all ecosystem models take into account the effect of changing stand structure during stand development on TSOIL dynamics. The goals of this study were to measure TSOIL and its spatiotemporal variability in a boreal forest chronosequence, develop and test a computationally simple empirical model to predict TSOIL, and quantify the effects of different approaches to deriving TSOIL on simulated ecosystem processes. TSOIL was measured hourly at six depths (0–100 cm) for 3–4 years, and sampled in a spatial grid monthly during one growing season, in a black spruce (Picea mariana (Mill.) BSP)-dominated boreal forest chronosequence. We report annual and daily TSOIL patterns, air–soil hystereses, and TSOIL changes at the freeze-thaw transition. An empirical model predicting TSOIL as of the weighted sum of past air temperatures generally accounted for 90–95% of temporal TSOIL variability at shallow depths, and 77–83% at 50–100 cm. A variety of stand structural characteristics affected the model parameters, with leaf area index (LAI) usually the most significant. Spatial TSOIL correlation, measured at depths of 2 and 10 cm, was generally constant between 5 and 30 m. The new empirical model that accounts for changes in canopy structure greatly improved the prediction of TSOIL for stands with high LAI in the Biome-BGC process model; the broader implications of this change are discussed. This model has simple data requirements – only air temperature and LAI – although the parameters given here should only be used for boreal stands with similar soil types.}, number={1-2}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Bond-Lamberty, B and Wang, CK and Gower, ST}, year={2005}, month={Jul}, pages={27–40} }
 @article{ahl_gower_mackay_burrows_norman_diak_2005, title={The effects of aggregated land cover data on estimating NPP in northern Wisconsin}, volume={97}, ISSN={["0034-4257"]}, DOI={10.1016/j.rse.2005.02.016}, abstractNote={Ecosystem models are routinely used to estimate net primary production (NPP) from the stand to global scales. Complex ecosystem models, implemented at small scales (< 10 km2), are impractical at global scales and, therefore, require simplifying logic based on key ecological first principles and model drivers derived from remotely sensed data. There is a need for an improved understanding of the factors that influence the variability of NPP model estimates at different scales so we can improve the accuracy of NPP estimates at the global scale. The objective of this study was to examine the effects of using leaf area index (LAI) and three different aggregated land cover classification products–two factors derived from remotely sensed data and strongly affect NPP estimates–in a light use efficiency (LUE) model to estimate NPP in a heterogeneous temperate forest landscape in northern Wisconsin, USA. Three separate land cover classifications were derived from three different remote sensors with spatial resolutions of 15, 30, and 1000 m. Average modeled net primary production (NPP) ranged from 402 gC m− 2 year− 1 (15 m data) to 431 gC m− 2 year− 1 (1000 m data), for a maximum difference of 7%. Almost 50% of the difference was attributed each to LAI estimates and land cover classifications between the fine and coarse scale NPP estimate. Results from this study suggest that ecosystem models that use biome-level land cover classifications with associated LUE coefficients may be used to model NPP in heterogeneous land cover areas dominated by cover types with similar NPP. However, more research is needed to examine scaling errors in other heterogeneous areas and NPP errors associated with deriving LAI estimates.}, number={1}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Ahl, DE and Gower, ST and Mackay, DS and Burrows, SN and Norman, JM and Diak, GR}, year={2005}, month={Jul}, pages={1–14} }
 @misc{bond-lamberty_wang_gower_2004, title={A global relationship between the heterotrophic and autotrophic components of soil respiration?}, volume={10}, ISSN={["1365-2486"]}, DOI={10.1111/j.1365-2486.2004.00816.x}, abstractNote={Abstract}, number={10}, journal={GLOBAL CHANGE BIOLOGY}, author={Bond-Lamberty, B and Wang, CK and Gower, ST}, year={2004}, month={Oct}, pages={1756–1766} }
 @article{bond-lamberty_wang_gower_2004, title={Contribution of root respiration to soil surface CO2 flux in a boreal black spruce chronosequence}, volume={24}, ISSN={["1758-4469"]}, DOI={10.1093/treephys/24.12.1387}, abstractNote={We quantified the contributions of root respiration (RC) and heterotrophic respiration to soil surface CO2 flux (RS) by comparing trenched and untrenched plots in well-drained and poorly drained stands of a black spruce (Picea mariana (Mill.) BSP) fire chronosequence in northern Manitoba, Canada. Our objectives were to: (1) test different equations for modeling RS as a function of soil temperature; and (2) model annual RS and RC for the chronosequence from continuous soil temperature measurements. The choice of equation to model RS strongly affected annual RS and RC, with an Arrhenius-based model giving the best fit to the data, especially at low temperatures. Modeled values of annual RS were positively correlated with soil temperature at 2-cm depth and were affected by year of burn and trenching, but not by soil drainage. During the growing season, measured RC was low in May, peaked in late July and declined to low values by the end of the growing season. Annual RC was < 5% of RS in the recently burned stands, approximately 40% in the 21-year-old stands and 5-15% in the oldest (152-year-old) stands. Evidence suggests that RC may have been underestimated in the oldest stands, with residual root decay from trenching accounting for 5-10% of trenched plot RS at most sites.}, number={12}, journal={TREE PHYSIOLOGY}, author={Bond-Lamberty, B and Wang, CK and Gower, ST}, year={2004}, month={Dec}, pages={1387–1395} }
 @misc{howard_gower_foley_kucharik_2004, title={Effects of logging on carbon dynamics of a jack pine forest in Saskatchewan, Canada}, volume={10}, ISSN={["1365-2486"]}, DOI={10.1111/j.1529-8817.2003.00804.x}, abstractNote={Abstract}, number={8}, journal={GLOBAL CHANGE BIOLOGY}, author={Howard, EA and Gower, ST and Foley, JA and Kucharik, CJ}, year={2004}, month={Aug}, pages={1267–1284} }
 @article{ahl_gower_mackay_burrows_norman_diak_2004, title={Heterogeneity of light use efficiency in a northern Wisconsin forest: implications for modeling net primary production with remote sensing}, volume={93}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2004.07.003}, abstractNote={Light use efficiency (LUE) models are often used with remotely sensed data products to estimate net primary production (NPP) from local to global scales. However, data on the variability of the LUE coefficient, ɛ, on the landscape are minimal and sometimes conflicting. The objectives of this study were to (1) quantify and compare the variability of LUE among five forest cover types: aspen, northern hardwoods, red pine, forested wetland, and upland conifer; and (2) quantify the variability of ɛ between two years, 1999 and 2000, and relate differences to environmental conditions. The study site was in a northern temperate forest in Wisconsin, USA. Northern hardwood forests, primarily consisting of sugar maple, had the highest ɛ each year followed by aspen, red pine, forested wetlands, and upland conifer. NPP was estimated using radial growth measurements and published allometric equations. Absorbed photosynthetically active radiation (APAR) was estimated optically using a Li-Cor Plant Canopy Analyzer. Growing season ɛ of all forest cover types increased significantly from 0.42 in 1999 to 0.47 (gC MJ−1) in 2000. Annual ɛ of all forest cover types increased significantly from 0.33 in 1999 to 0.36 (gC MJ−1) in 2000. Growing season and annual ɛ differed significantly (p≤0.001) among forest cover types for each year. Future research should consider variations in LUE among mixtures of many land cover types, especially forested wetlands. Results from this study show that LUE models should consider species-specific efficiency factors rather than biome-specific factors. Remote sensing-based land cover classifications should also reflect species differences for this area if the classification map is used in estimating NPP with an LUE model.}, number={1-2}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Ahl, DE and Gower, ST and Mackay, DS and Burrows, SN and Norman, JM and Diak, GR}, year={2004}, month={Oct}, pages={168–178} }
 @article{lee_cohen_kennedy_maiersperger_gower_2004, title={Hyperspectral versus multispectral data for estimating leaf area index in four different biomes}, volume={91}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2004.04.010}, abstractNote={Motivated by the increasing importance of hyperspectral remote sensing data, this study sought to determine whether current-generation narrow-band hyperspectral remote sensing data could better track vegetation leaf area index (LAI) than traditional broad-band multispectral data. The study takes advantage of a unique dataset, wherein field measurements of LAI were acquired at the same general time and grain size as both Landsat ETM+ and AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) imagery in four different biomes. Biome types sampled included row-crop agriculture, tallgrass prairie, mixed hardwood-conifer forest, and boreal conifer forest. The effects of bandwidth, band placement, and number of bands were isolated from radiometric quality by comparing regression models derived from individual AVIRIS channels with those derived from simulated ETM+ and MODIS channels using the AVIRIS data. Models with selected subsets of individual AVIRIS channels performed better to predict LAI than those based on the broadband datasets, although the potential to overfit models using the large number of available AVIRIS bands is a concern. Models based on actual ETM+ data were generally stronger than those based on simulated ETM+ data, suggesting that, for predicting LAI, ETM+ data suffer no penalty for having lower radiometric quality. NDVI was generally not sensitive to LAI at the four sites. Band placement of broad-band sensors (e.g., simulated ETM+ and MODIS) did not affect relationships with LAI, suggesting that there is no inherent advantage to MODIS spectral properties over those of ETM+ for estimating LAI. Spectral channels in the red-edge and shortwave-infrared regions were generally more important than those in the near-infrared for predicting LAI.}, number={3-4}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Lee, KS and Cohen, WB and Kennedy, RE and Maiersperger, TK and Gower, ST}, year={2004}, month={Jun}, pages={508–520} }
 @misc{bond-lamberty_wang_gower_2004, title={Net primary production and net ecosystem production of a boreal black spruce wildfire chronosequence}, volume={10}, ISSN={["1365-2486"]}, DOI={10.1111/j.1529-8817.2003.0742.x}, abstractNote={Abstract}, number={4}, journal={GLOBAL CHANGE BIOLOGY}, author={Bond-Lamberty, B and Wang, CK and Gower, ST}, year={2004}, month={Apr}, pages={473–487} }
 @article{turner_urbanski_bremer_wofsy_meyers_gower_gregory_2003, title={A cross-biome comparison of daily light use efficiency for gross primary production}, volume={9}, ISSN={["1365-2486"]}, DOI={10.1046/j.1365-2486.2003.00573.x}, abstractNote={Abstract}, number={3}, journal={GLOBAL CHANGE BIOLOGY}, author={Turner, DP and Urbanski, S and Bremer, D and Wofsy, SC and Meyers, T and Gower, ST and Gregory, M}, year={2003}, month={Mar}, pages={383–395} }
 @article{cohen_maiersperger_gower_turner_2003, title={An improved strategy for regression of biophysical variables and Landsat ETM+ data}, volume={84}, ISSN={["1879-0704"]}, DOI={10.1016/s0034-4257(02)00173-6}, abstractNote={Empirical models are important tools for relating field-measured biophysical variables to remote sensing data. Regression analysis has been a popular empirical method of linking these two types of data to provide continuous estimates for variables such as biomass, percent woody canopy cover, and leaf area index (LAI). Traditional methods of regression are not sufficient when resulting biophysical surfaces derived from remote sensing are subsequently used to drive ecosystem process models. Most regression analyses in remote sensing rely on a single spectral vegetation index (SVI) based on red and near-infrared reflectance from a single date of imagery. There are compelling reasons for utilizing greater spectral dimensionality, and for including SVIs from multiple dates in a regression analysis. Moreover, when including multiple SVIs and/or dates, it is useful to integrate these into a single index for regression modeling. Selection of an appropriate regression model, use of multiple SVIs from multiple dates of imagery as predictor variables, and employment of canonical correlation analysis (CCA) to integrate these multiple indices into a single index represent a significant strategic improvement over existing uses of regression analysis in remote sensing. To demonstrate this improved strategy, we compared three different types of regression models to predict LAI for an agro-ecosystem and live tree canopy cover for a needleleaf evergreen boreal forest: traditional (Y on X) ordinary least squares (OLS) regression, inverse (X on Y) OLS regression, and an orthogonal regression method called reduced major axis (RMA). Each model incorporated multiple SVIs from multiple dates and CCA was used to integrate these. For a given dataset, the three regression-modeling approaches produced identical coefficients of determination and intercepts, but different slopes, giving rise to divergent predictive characteristics. The traditional approach yielded the lowest root mean square error (RMSE), but the variance in the predictions was lower than the variance in the observed dataset. The inverse method had the highest RMSE and the variance was inflated relative to the variance of the observed dataset. RMA provided an intermediate set of predictions in terms of the RMSE, and the variance in the observations was preserved in the predictions. These results are predictable from regression theory, but that theory has been essentially ignored within the discipline of remote sensing.}, number={4}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Cohen, WB and Maiersperger, TK and Gower, ST and Turner, DP}, year={2003}, month={Apr}, pages={561–571} }
 @article{mackay_samanta_ahl_ewers_gower_2003, title={Automated parameterization of land surface process models using fuzzy logic}, volume={7}, DOI={10.1111/1467-9671.00134}, abstractNote={All land surface process models require parameters that are proxies for spatial processes that are impractical or impossible to measure. Recent developments in model parameter estimation theory suggest that information obtained from calibrating such models is inherently uncertain in nature. As a consequence, identification of optimum parameter values is often highly non–specific. A calibration framework using fuzzy logic is presented to deal with such uncertain information. An application of this technique to calibrate the sub–canopy controls on transpiration in a land surface process model demonstrates that objective estimates of parameter values and expected ranges of predictions can be obtained with suitable choices for objective functions. An iterative refinement in parameter estimates was possible with conditional sampling techniques. The automated approach was able to correctly identify parameter tradeoffs such that two strongly different sets of parameters could}, number={1}, journal={Transactions in GIS}, author={Mackay, D. S. and Samanta, S. and Ahl, D. E. and Ewers, B. E. and Gower, S. T.}, year={2003}, pages={139–153} }
 @article{wang_bond-lamberty_gower_2003, title={Carbon distribution of a well- and poorly-drained black spruce fire chronosequence}, volume={9}, ISSN={["1365-2486"]}, DOI={10.1046/j.1365-2486.2003.00645.x}, abstractNote={Abstract}, number={7}, journal={GLOBAL CHANGE BIOLOGY}, author={Wang, CK and Bond-Lamberty, B and Gower, ST}, year={2003}, month={Jul}, pages={1066–1079} }
 @article{keb o'connell_gower_norman_2003, title={Comparison of net primary production and light-use dynamics of two boreal black spruce forest communities}, volume={6}, ISSN={["1435-0629"]}, DOI={10.1007/pl00021510}, number={3}, journal={ECOSYSTEMS}, author={KEB O'Connell and Gower, ST and Norman, JM}, year={2003}, month={Apr}, pages={236–247} }
 @article{cohen_maiersperger_yang_gower_turner_ritts_berterretche_running_2003, title={Comparisons of land cover and LAI estimates derived from ETM plus and MODIS for four sites in North America: a quality assessment of 2000/2001 provisional MODIS products}, volume={88}, ISSN={["0034-4257"]}, DOI={10.1016/j.rse.2003.06.006}, abstractNote={The MODIS land science team produces a number of standard products, including land cover and leaf area index (LAI). Critical to the success of MODIS and other sensor products is an independent evaluation of product quality. In that context, we describe a study using field data and Landsat ETM+ to map land cover and LAI at four 49-km2 sites in North America containing agricultural cropland (AGRO), prairie grassland (KONZ), boreal needleleaf forest, and temperate mixed forest. The purpose was to: (1) develop accurate maps of land cover, based on the MODIS IGBP (International Geosphere–Biosphere Programme) land cover classification scheme; (2) derive continuous surfaces of LAI that capture the mean and variability of the LAI field measurements; and (3) conduct initial MODIS validation exercises to assess the quality of early (i.e., provisional) MODIS products. ETM+ land cover maps varied in overall accuracy from 81% to 95%. The boreal forest was the most spatially complex, had the greatest number of classes, and the lowest accuracy. The intensive agricultural cropland had the simplest spatial structure, the least number of classes, and the highest overall accuracy. At each site, mapped LAI patterns generally followed patterns of land cover across the site. Predicted versus observed LAI indicated a high degree of correspondence between field-based measures and ETM+ predictions of LAI. Direct comparisons of ETM+ land cover maps with Collection 3 MODIS cover maps revealed several important distinctions and similarities. One obvious difference was associated with image/map resolution. ETM+ captured much of the spatial complexity of land cover at the sites. In contrast, the relatively coarse resolution of MODIS did not allow for that level of spatial detail. Over the extent of all sites, the greatest difference was an overprediction by MODIS of evergreen needleleaf forest cover at the boreal forest site, which consisted largely of open shrubland, woody savanna, and savanna. At the agricultural, temperate mixed forest, and prairie grassland sites, ETM+ and MODIS cover estimates were similar. Collection 3 MODIS-based LAI estimates were considerably higher (up to 4 m2 m−2) than those based on ETM+ LAI at each site. There are numerous probable reasons for this, the most important being the algorithms' sensitivity to MODIS reflectance calibration, its use of a prelaunch AVHRR-based land cover map, and its apparent reliance on mainly red and near-IR reflectance. Samples of Collection 4 LAI products were examined and found to consist of significantly improved LAI predictions for KONZ, and to some extent for AGRO, but not for the other two sites. In this study, we demonstrate that MODIS reflectance data are highly correlated with LAI across three study sites, with relationships increasing in strength from 500 to 1000 m spatial resolution, when shortwave-infrared bands are included.}, number={3}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Cohen, WB and Maiersperger, TK and Yang, ZQ and Gower, ST and Turner, DP and Ritts, WD and Berterretche, M and Running, SW}, year={2003}, month={Dec}, pages={233–255} }
 @article{brye_norman_gower_bundy_2003, title={Effects of management practices on annual net N-mineralization in a restored prairie and maize agroecosystems}, volume={63}, number={2}, journal={Biogeochemistry}, author={Brye, K. R. and Norman, J. M. and Gower, S. T. and Bundy, L. G.}, year={2003}, pages={135–160} }
 @article{feldkirchner_wang_gower_kruger_ferris_2003, title={Effects of nutrient and paper mill biosolids amendments on the growth and nutrient status of hardwood forests}, volume={177}, ISSN={["0378-1127"]}, DOI={10.1016/s0378-1127(02)00318-3}, abstractNote={Aboveground net primary productivity (ANPP) and soil and vegetation nutrient concentrations were measured in pole-sized northern hardwood and aspen forests to quantify the potential for various nutrient amendments to increase tree growth, as well as potential deleterious effects on vegetation. Four blocks were installed in each forest type containing the following treatments: control, N+Ca+Mg+K+P+S (complete), wood-fired boiler ash (ash), N+wood-fired boiler ash (N+ash), and two rates of paper mill sludge (sludge and 2× sludge). The northern hardwood forests had three additional treatments: N, Ca+Mg+K (base cations), and N+Ca+Mg+K (N+base cations). Fertilizer treatments were designed to provide N at a rate of 100 kg ha−1. Other nutrients were applied in proportion to N so that N, P, K, S, Mg, and Ca were applied at a ratio of 100:50:33:9:5:4, respectively. Total ANPP was not significantly different among treatments for the maple stands, but plots treated with wood ash were 10% greater than controls. ANPP was greater in 1998 and 1999 for aspen plots receiving N+ash, but results were only statistically significant (p=0.013) in 1999. Basal area differed by 40–60% among experimental plots within any given block and was positively correlated to wood increment. Wood increment, adjusted for basal area, did not differ significantly among treatments for the aspen stands, but the N+ash treatment was 30% greater than the control. A two-way factorial comparison indicated that ash had a significant (p=0.024) positive effect on wood increment and N had a significant (p=0.044) negative effect on wood increment for the maple stands. Tree growth was not correlated to foliar nutrient concentrations, but ratios of K to other elements (K:Ca, K:Mg, K:N, and K:P) were highest, on average, for wood ash plots. These differences were not statistically significant with the exception of K:N for the aspen stands and K:Ca for the maple stands. We did not observe any beneficial effects of paper mill sludge on forest growth, but there was some evidence that wood ash increased annual wood production.}, number={1-3}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Feldkirchner, DC and Wang, C and Gower, ST and Kruger, EL and Ferris, J}, year={2003}, month={Apr}, pages={95–116} }
 @article{brye_norman_gower_bundy_2003, title={Methodological limitations and N-budget differences among a restored tallgrass prairie and maize agroecosystems}, volume={97}, ISSN={["0167-8809"]}, DOI={10.1016/s0167-8809(03)00067-7}, abstractNote={Interpretation of elemental balances requires careful assessment of component terms and their errors, especially for the major terms of the nitrogen (N) budget which has implications for environmental health. This study reports results from independent field measurements of major annual N-budget components, including atmospheric deposition, fertilizer added, net mineralization, residue returned, soil storage changes of inorganic N, leaching, and plant uptake. Measurements were made in a restored tallgrass prairie and optimally and deficiently N-fertilized, no-tillage and chisel-plowed maize (Zea mays L.) agroecosystems on Plano silt loam soil (fine-silty, mixed, superactive, mesic Typic Argiudoll (USDA); Haplic Phaeozem (approximate FAO)) in Wisconsin between 1995 and 1999. Denitrification and N losses due to runoff were assumed negligible and bulk density was assumed uniform with depth and across ecosystems. Annual inorganic N leaching was negligible in the restored prairie, but represented 3–57% of the amount of fertilizer-N applied in the optimally N-fertilized agroecosystems. On an annual basis, closure of the inorganic-N budget yielded cumulative errors that were often undesirably large; indicating methodological problems with quantifying ecosystem N cycling in situ. Increased spatial sampling is required to reduce individual measurement errors of two components with large uncertainties; namely net N-mineralization and soil inorganic N changes. Profile-scaled net N-mineralization generally did not balance with the residue N input from the previous year, but the imbalance agreed with the N-budget imbalance. Both results suggest that the prairie is accumulating N slowly, the deficiently N-fertilized maize plots are losing N more rapidly, and the optimally N-fertilized maize plots have too large an uncertainty to be interpreted confidently. Nitrogen-use efficiency, defined on a N-uptake basis, did not differ among the prairie and deficiently N-fertilized maize for 3 out of 5 years, but the prairie was significantly more efficient than the optimally N-fertilized maize.}, number={1-3}, journal={AGRICULTURE ECOSYSTEMS & ENVIRONMENT}, author={Brye, KR and Norman, JM and Gower, ST and Bundy, LG}, year={2003}, month={Jul}, pages={181–198} }
 @article{keb o'connell_gower_norman_2003, title={Net ecosystem production of two contrasting boreal black spruce forest communities}, volume={6}, ISSN={["1435-0629"]}, DOI={10.1007/pl00021511}, number={3}, journal={ECOSYSTEMS}, author={KEB O'Connell and Gower, ST and Norman, JM}, year={2003}, month={Apr}, pages={248–260} }
 @misc{gower_2003, title={Patterns and mechanisms of the forest carbon cycle}, volume={28}, ISSN={["1543-5938"]}, DOI={10.1146/annurev.energy.28.050302.105515}, abstractNote={Forests are an important source for fiber and fuel for humans and contain the majority of the total terrestrial carbon (C). The amount of C stored in the vegetation and soil are strongly influenced by environmental constraints on annual C uptake and decomposition and time since disturbance. Increasing concentrations of atmospheric carbon dioxide (CO2), nitrogen deposition, and climate warming induced by greater greenhouse gas (GHG) concentrations in the atmosphere influence C accumulation rates of forests, but their effects will likely differ in direction and magnitude among forest ecosystems. The net interactive effect of global change on the forest C cycle is poorly understood. The growing demand for wood fiber and fuel by humans and the ongoing anthropogenic perturbations of the climate have changed the natural disturbance regimes (i.e., frequency and intensity); these changes influence the net exchange of CO2between forests and the atmosphere. To date, the role of forest products in the global C cycle have largely been ignored, and important emissions associated with the production, transport, and utilization of the forest products have been excluded, leading to erroneous conclusions about net C storage in forest products.}, journal={ANNUAL REVIEW OF ENVIRONMENT AND RESOURCES}, author={Gower, ST}, year={2003}, pages={169–204} }
 @article{mackay_ahl_ewers_samanta_gower_burrows_2003, title={Physiological tradeoffs in the parameterization of a model of canopy transpiration}, volume={26}, ISSN={["1872-9657"]}, DOI={10.1016/s0309-1708(02)00090-8}, abstractNote={We examined physiological parameter tradeoffs in modeling stomatal control of transpiration from a number of forest species. Measurements of sapflux, micrometeorology, and leaf area index were made in stands representing 85% of the forest ecosystems around the WLEF eddy flux tower in northern Wisconsin. A Jarvis-based canopy conductance model was used to simulate canopy transpiration (EC) for five tree species from these stands. They consisted of conifers and deciduous species in both upland and wetland locations. Parameter estimation was used to assess the tradeoffs between physiological parameters used in the calculation of stomatal conductance. These tradeoffs were then evaluated against current theory on stomatal regulation of leaf water potential. The results show that the best simulations of EC were obtained with values of maximum stomatal conductance (gSmax) and stomatal sensitivity to vapor pressure deficit (δ) that closely followed this hydraulic theory. The model predictions reveal a large variation in the strategies used to regulate water potential among species. Aspen showed the greatest tendency towards efficiency, indicating that it has high EC under low vapor pressure deficit (D) conditions, but is susceptible to rapid EC decline at moderate to high D. Other species showed more conservative water use. The results indicate that inter-specific differences in dynamic response to D can produce large spatial variation in EC under typical environmental conditions.}, number={2}, journal={ADVANCES IN WATER RESOURCES}, author={Mackay, DS and Ahl, DE and Ewers, BE and Samanta, S and Gower, ST and Burrows, SN}, year={2003}, month={Feb}, pages={179–194} }
 @article{turner_ritts_cohen_gower_zhao_running_wofsy_urbanski_dunn_munger_2003, title={Scaling Gross Primary Production (GPP) over boreal and deciduous forest landscapes in support of MODIS GPP product validation}, volume={88}, ISSN={["1879-0704"]}, DOI={10.1016/j.rse.2003.06.005}, abstractNote={The Moderate Resolution Imaging Radiometer (MODIS) is the primary instrument in the NASA Earth Observing System for monitoring the seasonality of global terrestrial vegetation. Estimates of 8-day mean daily gross primary production (GPP) at the 1 km spatial resolution are now operationally produced by the MODIS Land Science Team for the global terrestrial surface using a production efficiency approach. In this study, the 2001 MODIS GPP product was compared with scaled GPP estimates (25 km2) based on ground measurements at two forested sites. The ground-based GPP scaling approach relied on a carbon cycle process model run in a spatially distributed mode. Land cover classification and maximum annual leaf area index, as derived from Landsat ETM+ imagery, were used in model initiation. The model was driven by daily meteorological observations from an eddy covariance flux tower situated at the center of each site. Model simulated GPPs were corroborated with daily GPP estimates from the flux tower. At the hardwood forest site, the MODIS GPP phenology started earlier than was indicated by the scaled GPP, and the summertime GPP from MODIS was generally lower than the scaled GPP values. The fall-off in production at the end of the growing season was similar to the validation data. At the boreal forest site, the GPP phenologies generally agreed because both responded to the strong signal associated with minimum temperature. The midsummer MODIS GPP there was generally higher than the ground-based GPP. The differences between the MODIS GPP products and the ground-based GPPs were driven by differences in the timing of FPAR and the magnitude of light use efficiency as well as by differences in other inputs to the MODIS GPP algorithm—daily incident PAR, minimum temperature, and vapor pressure deficit. Ground-based scaling of GPP has the potential to improve the parameterization of light use efficiency in satellite-based GPP monitoring algorithms.}, number={3}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Turner, DP and Ritts, WD and Cohen, WB and Gower, ST and Zhao, MS and Running, SW and Wofsy, SC and Urbanski, S and Dunn, AL and Munger, JW}, year={2003}, month={Dec}, pages={256–270} }
 @article{burrows_gower_norman_diak_mackay_ahl_clayton_2003, title={Spatial variability of aboveground net primary production for a forested landscape in northern Wisconsin}, volume={33}, ISSN={["0045-5067"]}, DOI={10.1139/x03-124}, abstractNote={ Quantifying forest net primary production (NPP) is critical to understanding the global carbon cycle because forests are responsible for a large portion of the total terrestrial NPP. The objectives of this study were to measure above ground NPP (NPPA) for a land surface in northern Wisconsin, examine the spatial patterns of NPPA and its components, and correlate NPPA with vegetation cover types and leaf area index. Mean NPPA for aspen, hardwoods, mixed forest, upland conifers, nonforested wetlands, and forested wetlands was 7.8, 7.2, 5.7, 4.9, 5.0, and 4.5 t dry mass·ha–1·year–1, respectively. There were significant (p = 0.01) spatial patterns in wood, foliage, and understory NPP components and NPPA (p = 0.03) when the vegetation cover type was included in the model. The spatial range estimates for the three NPP components and NPPA differed significantly from each other, suggesting that different factors are influencing the components of NPP. NPPA was significantly correlated with leaf area index (p = 0.01) for the major vegetation cover types. The mean NPPA for the 3 km × 2 km site was 5.8 t dry mass·ha–1·year–1. }, number={10}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={Burrows, SN and Gower, ST and Norman, JM and Diak, G and Mackay, DS and Ahl, DE and Clayton, MK}, year={2003}, month={Oct}, pages={2007–2018} }
 @article{bond-lamberty_wang_gower_2003, title={The use of multiple measurement techniques to refine estimates of conifer needle geometry}, volume={33}, ISSN={["0045-5067"]}, DOI={10.1139/x02-166}, abstractNote={ Knowledge of foliar surface area is important in many fields, but estimating the area of nonflat conifer needles is difficult. The primary goal of this study was to use optical scanning and immersion methods to test and refine the standard cross-sectional geometries assumed for black spruce (Picea mariana (Mill.) BSP) and jack pine (Pinus banksiana Lamb.) needles. Projected leaf area (PLA, measured using a flatbed scanner), and hemisurface leaf area (HSLA, estimated from water immersion) were compared for conifer samples from a 37-year-old even-aged stand in northern Manitoba, Canada. The HSLA–PLA relationship was used to infer information about needle cross-sectional geometry after assuming a basic form (rhombus for black spruce and hemiellipse for jack pine). The cross section of black spruce needles was best approximated as a rhombus with a major/minor diagonal ratio of 1.35. Jack pine needles were best described by a hemiellipse with major/minor axis ratio of 1.30. Minor but incorrect assumptions of needle cross-sectional geometry resulted in foliar area errors of 6–8% using scanning methods and 1–2% using immersion methods. Simple equations are presented to calculate hemisurface needle area from volume or projected needle area based on these refined parameters. }, number={1}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={Bond-Lamberty, B and Wang, C and Gower, ST}, year={2003}, month={Jan}, pages={101–105} }
 @article{bond-lamberty_wang_gower_2002, title={Aboveground and belowground biomass and sapwood area allometric equations for six boreal tree species of northern Manitoba}, volume={32}, ISSN={["0045-5067"]}, DOI={10.1139/x02-063}, abstractNote={Allometric equations were developed relating aboveground biomass, coarse root biomass, and sapwood area to stem diameter at 17 study sites located in the boreal forests near Thompson, Man. The six species studied were trembling aspen (Populus tremuloides Michx.), paper birch (Betula papyrifera Marsh.), black spruce (Picea mariana (Mill.) BSP), jack pine (Pinus banksiana Lamb.), tamarack (Larix laricina (Du Roi) Koch.), and willow (Salix spp.). Stands ranged in age from 4 to 130 years and were categorized as well or poorly drained. Stem diameter ranged from 0.1 to 23.7 cm. Stem diameter was measured at both the soil surface (D0) and breast height (DBH). The relationship between biomass and diameter, fitted on a log–log scale, changed significantly at ~3 cm DBH, suggesting that allometry differed between saplings and older trees. To eliminate this nonlinearity, a model of form log10Y = a + b(log10D) + c(AGE) + d(log10D × AGE) was used, where D is stem diameter, AGE is stand age, and the cross product is the interaction between diameter and age. Most aboveground biomass equations (N = 326) exhibited excellent fits (R2> 0.95). Coarse root biomass equations (N = 205) exhibited good fits (R2> 0.90). Both D0and DBH were excellent (R2> 0.95) sapwood area predictors (N = 413). Faster growing species had significantly higher ratios of sapwood area to stem area than did slower growing species. Nonlinear aspects of some of the pooled biomass equations serve as a caution against extrapolating allometric equations beyond the original sample diameter range.}, number={8}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={Bond-Lamberty, B and Wang, C and Gower, ST}, year={2002}, month={Aug}, pages={1441–1450} }
 @article{bond-lamberty_wang_gower_2002, title={Annual carbon flux from woody debris for a boreal black spruce fire chronosequence}, volume={108}, ISSN={["2169-8996"]}, DOI={10.1029/2001jd000839}, abstractNote={This study examined the distribution and respiration dynamics of woody debris (WD) in a black spruce‐dominated fire chronosequence in northern Manitoba, Canada. The chronosequence included seven stands that burned between 1870 and 1998; each stand contained separate well‐drained and poorly drained areas. The objectives of this study were to (1) quantify the distribution of WD, by diameter and decay class, in well‐drained and poorly drained stands across the chronosequence, (2) measure the evolution of CO2 from WD samples and model the effects of moisture, size and decay on respiration, and (3) model annual WD respiration and compute decay constants for each site. Coarse woody debris biomass ranged from 1.4 Mg ha−1 to 177.6 Mg ha−1, generally declining in the older stands of the chronosequence. More decayed WD had significantly (α = 0.05) higher moisture, lower density, and higher respiration rates than less decayed WD. Moisture and decay class were significant predictors of respiration when moisture was below 43%. Above this level, moisture was not significant, but stand soil drainage was significant, with drier sites having higher WD respiration. Year of burn was not significant in the respiration models. Modeled annual carbon emissions from WD ranged from 0.11 to 1.92 Mg C ha−1 yr−1. Modeled annual decay rates, between k = 0.01 and k = 0.06, changed across the age sequence. Thus a single‐exponential decay model may not be appropriate for the age sequence. Calculating k directly from wood respiration measurements, as done here, may be useful in allowing examination of year‐to‐year changes in k.}, number={D3}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Bond-Lamberty, B and Wang, C and Gower, ST}, year={2002}, month={Oct} }
 @article{burrows_gower_clayton_mackay_ahl_norman_diak_2002, title={Application of geostatistics to characterize leaf area index (LAI) from flux tower to landscape scales using a cyclic sampling design}, volume={5}, number={7}, journal={Ecosystems}, author={Burrows, S. N. and Gower, S. T. and Clayton, M. K. and Mackay, D. S. and Ahl, D. E. and Norman, J. M. and Diak, G.}, year={2002}, pages={667–679} }
 @article{brye_norman_gower_2002, title={Assessing the progress of a tallgrass prairie restoration in Southern Wisconsin}, volume={148}, ISSN={["1938-4238"]}, DOI={10.1674/0003-0031(2002)148[0218:atpoat]2.0.co;2}, abstractNote={Abstract Assessments of ecosystem restorations are necessary to improve restoration practices and goals. Restoration assessments, whether quantitative or qualitative, are also a vital part of managing previously degraded ecosystems. This study examined some of the key structural and functional characteristics and processes of a tallgrass prairie restoration near Arlington, Wisconsin for 5 y, 19 to 24 y after beginning restoration from cultivation, including mean annual drainage, N and C leaching, soil organic matter, pH, extractable P and K, total N and C contents, above- and belowground net primary production, leaf area index, soil surface CO2 flux and net N-mineralization. Total soil N and C contents of the prairie restoration were compared to other nearby prairie restorations, remnants and an adjacent agricultural field, all on similar soil, to determine the degree of change in ecosystem properties as a result of ecological restoration. Soil properties and processes and vegetation characteristics varied annually throughout the 5-y assessment period, but most soil properties showed no significant temporal trend. Only soil N content in the 0–30 cm layer increased significantly in the 5-y period, but the rate of N increase did not coincide with the rate typical of N inputs to a prairie. Results suggest that most soil properties have either already come to some equilibrium with the surrounding environment or their rates of change were too small to measure over 5 y. This study demonstrates the difficulties of ascribing changes in ecosystem properties to restoration. The spatial and temporal variability and slow rates of change make it difficult to discern differences between restored, disturbed and natural ecosystems.}, number={2}, journal={AMERICAN MIDLAND NATURALIST}, author={Brye, KR and Norman, JM and Gower, ST}, year={2002}, month={Oct}, pages={218–235} }
 @article{brye_gower_norman_bundy_2002, title={Carbon budgets for a prairie and agroecosystems: Effects of land use and interannual variability}, volume={12}, DOI={10.2307/3061030}, number={4}, journal={Ecological Applications}, author={Brye, K. R. and Gower, S. T. and Norman, J. M. and Bundy, L. G.}, year={2002}, pages={962–979} }
 @article{mackay_ahl_ewers_gower_burrows_samanta_davis_2002, title={Effects of aggregated classifications of forest composition on estimates of evapotranspiration in a northern Wisconsin forest}, volume={8}, ISSN={["1365-2486"]}, DOI={10.1046/j.1365-2486.2002.00554.x}, abstractNote={Abstract}, number={12}, journal={GLOBAL CHANGE BIOLOGY}, author={MacKay, DS and Ahl, DE and Ewers, BE and Gower, ST and Burrows, SN and Samanta, S and Davis, KJ}, year={2002}, month={Dec}, pages={1253–1265} }
 @article{turner_gower_cohen_gregory_maiersperger_2002, title={Effects of spatial variability in light use efficiency on satellite-based NPP monitoring}, volume={80}, ISSN={["1879-0704"]}, DOI={10.1016/s0034-4257(01)00319-4}, abstractNote={Light use efficiency (LUE) algorithms are a potentially effective approach to monitoring global net primary production (NPP) using satellite-borne sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS). However, these algorithms are applied at relatively coarse spatial resolutions (≥1 km), which may subsume significant heterogeneity in vegetation LUE (ϵn, g MJ−1) and, hence, introduce error. To examine the effects of spatial heterogeneity on a LUE algorithm, imagery from the Advanced Very High Resolution Radiometer (AVHRR) at ≈1-km resolution was used to implement a LUE approach for NPP estimation over a 25-km2 area of corn (Zea mays L.) and soybean (Glycine max Merr.) in central Illinois, USA. Results from several ϵn formulations were compared with a NPP reference surface based on measured NPPs and a high spatial resolution land cover surface derived from Landsat ETM+. Determination of ϵn based on measurements of biomass production and monitoring of absorbed photosynthetically active radiation (APAR) revealed that ϵn of soybean was 68% of that for corn. When a LUE algorithm for estimating NPP was implemented in the study area using the assumption of homogeneous cropland and the ϵn for corn, the estimate for total biomass production was 126% of that from the NPP reference surface. Because of counteracting errors, total biomass production using the soybean ϵn was closer (86%) to that from the NPP reference surface. Retention of high spatial resolution land cover to assign ϵn resulted in a total NPP very similar to the reference NPP because differences in leaf phenology between the crop types were small except early in the growing season. These results suggest several alternative approaches to accounting for land cover heterogeneity in ϵn when implementing LUE algorithms at coarse resolution.}, number={3}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Turner, DP and Gower, ST and Cohen, WB and Gregory, M and Maiersperger, TK}, year={2002}, month={Jun}, pages={397–405} }
 @article{wang_bond-lamberty_gower_2002, title={Environmental controls on carbon dioxide flux from black spruce coarse woody debris}, volume={132}, ISSN={["1432-1939"]}, DOI={10.1007/s00442-002-0987-4}, number={3}, journal={OECOLOGIA}, author={Wang, CK and Bond-Lamberty, B and Gower, ST}, year={2002}, month={Aug}, pages={374–381} }
 @article{mcguire_wirth_apps_beringer_clein_epstein_kicklighter_bhatti_chapin_degroot_et al._2002, title={Environmental variation, vegetation distribution, carbon dynamics and water/energy exchange at high latitudes}, volume={13}, DOI={10.1111/j.1654-1103.2002.tb02055.x}, abstractNote={Abstract.  The responses of high latitude ecosystems to global change involve complex interactions among environmental variables, vegetation distribution, carbon dynamics, and water and energy exchange. These responses may have important consequences for the earth system. In this study, we evaluated how vegetation distribution, carbon stocks and turnover, and water and energy exchange are related to environmental variation spanned by the network of the IGBP high latitude transects. While the most notable feature of the high latitude transects is that they generally span temperature gradients from southern to northern latitudes, there are substantial differences in temperature among the transects. Also, along each transect temperature co‐varies with precipitation and photosynthetically active radiation, which are also variable among the transects. Both climate and disturbance interact to influence latitudinal patterns of vegetation and soil carbon storage among the transects, and vegetation distribution appears to interact with climate to determine exchanges of heat and moisture in high latitudes. Despite limitations imposed by the data we assembled, the analyses in this study have taken an important step toward clarifying the complexity of interactions among environmental variables, vegetation distribution, carbon stocks and turnover, and water and energy exchange in high latitude regions. This study reveals the need to conduct coordinated global change studies in high latitudes to further elucidate how interactions among climate, disturbance, and vegetation distribution influence carbon dynamics and water and energy exchange in high latitudes.}, number={3}, journal={Journal of Vegetation Science}, author={McGuire, A. D. and Wirth, C. and Apps, M. and Beringer, J. and Clein, J. and Epstein, H. and Kicklighter, D. W. and Bhatti, J. and Chapin, F. S. and deGroot, B. and et al.}, year={2002}, pages={301–314} }
 @article{harden_mack_veldhuis_gower_2002, title={Fire dynamics and implications for nitrogen cycling in boreal forests}, volume={108}, ISSN={["2169-8996"]}, DOI={10.1029/2001jd000494}, abstractNote={We used a dynamic, long‐term mass balance approach to track cumulative carbon (C) and nitrogen (N) losses to fire in boreal Manitoba over the 6500 years since deglaciation. Estimated C losses to decomposition and fire, combined with measurements of N pools in mature and burned forest floors, suggest that loss of N by combustion has likely resulted in a long‐term loss that exceeds the amount of N stored in soil today by 2 to 3 times. These estimates imply that biological N fixation rates could be as high as 5 to 10 times atmospheric deposition rates in boreal regions. At the site scale, the amount of N lost is due to N content of fuels, which varies by stand type and fire severity, which in turn vary with climate and fire dynamics. The interplay of fire frequency, fire severity, and N partitioning during regrowth are important for understanding rates and sustainability of nutrient and carbon cycling over millenia and over broad regions.}, number={D3}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Harden, JW and Mack, M and Veldhuis, H and Gower, ST}, year={2002}, month={Dec} }
 @article{bond-lamberty_wang_gower_norman_2002, title={Leaf area dynamics of a boreal black spruce fire chronosequence}, volume={22}, ISSN={["1758-4469"]}, DOI={10.1093/treephys/22.14.993}, abstractNote={Specific leaf area (SLA) and leaf area index (LAI) were estimated using site-specific allometric equations for a boreal black spruce (Picea mariana (Mill.) BSP) fire chronosequence in northern Manitoba, Canada. Stands ranged from 3 to 131 years in age and had soils that were categorized as well or poorly drained. The goals of the study were to: (i) measure SLA for the dominant tree and understory species of boreal black spruce-dominated stands, and examine the effect of various biophysical conditions on SLA; and (ii) examine leaf area dynamics of both understory and overstory for well- and poorly drained stands in the chronosequence. Overall, average SLA values for black spruce (n = 215), jack pine (Pinus banksiana Lamb., n = 72) and trembling aspen (Populus tremuloides Michx., n = 27) were 5.82 +/- 1.91, 5.76 +/- 1.91 and 17.42 +/- 2.21 m2 x kg-1, respectively. Foliage age, stand age, vertical position in the canopy and soil drainage had significant effects on SLA. Black spruce dominated overstory LAI in the older stands. Well-drained stands had significantly higher overstory LAI (P < 0.001), but lower understory LAI (P = 0.022), than poorly drained stands. Overstory LAI was negligible in the recent (3-12 years old) burn sites and highest in the 70-year-old burn site (6.8 and 3.0 in the well- and poorly drained stands, respectively), declining significantly (by 30-50%) from this peak in the oldest stands. Understory leaf area represented a significant portion (> 40%) of total leaf area in all stands except the oldest.}, number={14}, journal={TREE PHYSIOLOGY}, author={Bond-Lamberty, B and Wang, C and Gower, ST and Norman, J}, year={2002}, month={Oct}, pages={993–1001} }
 @article{lefsky_cohen_harding_parker_acker_gower_2002, title={Lidar remote sensing of above-ground biomass in three biomes}, volume={11}, ISSN={["1466-8238"]}, DOI={10.1046/j.1466-822x.2002.00303.x}, abstractNote={Abstract}, number={5}, journal={GLOBAL ECOLOGY AND BIOGEOGRAPHY}, author={Lefsky, MA and Cohen, WB and Harding, DJ and Parker, GG and Acker, SA and Gower, ST}, year={2002}, month={Sep}, pages={393–399} }
 @article{brye_norman_nordheim_gower_bundy_2002, title={Refinements to an in-situ soil core technique for measuring net nitrogen mineralization in moist, fertilized agricultural soil}, volume={94}, DOI={10.2134/agronj2002.0864}, abstractNote={Diffusion of NO−3–N ions and nonuniform distribution of surface-applied N fertilizers contribute to large variations in field measurements of net N mineralization. An in situ soil core–ion exchange resin bag (ISC–IERB) field method has been used reliably to measure net N mineralization in intact soil cores but has not been widely tested in moist, though nonirrigated, N-fertilized agricultural soils. From 1996 through 2000, net N mineralization was measured in the top 20 cm using a refined version of the ISC/IERB technique for the first 1-mo period following planting and fertilization of N-fertilized and N-unfertilized, no-tillage and chisel-plowed corn (Zea mays L.) agroecosystems on Plano silt loam (fine-silty, mixed, superactive, mesic, typic argiudoll) in south-central Wisconsin. Progressive modifications were made to the ISC/IERB technique, which ultimately resulted in reduced sample variability. Following the refinements, a significant N fertilization effect was shown for the most variable period of the growing season where net N mineralization rates for N-fertilized corn treatments were significantly higher (p < 0.001) than for N-unfertilized corn treatments.}, number={4}, journal={Agronomy Journal}, author={Brye, K. R. and Norman, J. M. and Nordheim, E. V. and Gower, S. T. and Bundy, L. G.}, year={2002}, pages={864–869} }
 @article{wang_bond-lamberty_gower_2002, title={Soil surface CO2 flux in a boreal black spruce fire chronosequence}, volume={108}, ISSN={["2169-8996"]}, DOI={10.1029/2001jd000861}, abstractNote={Understanding the effects of wildfire on the carbon (C) cycle of boreal forests is essential to quantifying the role of boreal forests in the global carbon cycle. Soil surface CO2 flux (Rs), the second largest C flux in boreal forests, is directly and indirectly affected by fire and is hypothesized to change during forest succession following fire. The overall objective of this study was to measure and model Rs for a black spruce (Picea mariana [Mill.] BSP) postfire chronosequence in northern Manitoba, Canada. The experiment design was a nested factorial that included two soil drainage classes (well and poorly drained) × seven postfire aged stands. Specific objectives were (1) to quantify the relationship between Rs and soil temperature for different aged boreal black spruce forests in well‐drained and poorly drained soil conditions, (2) to examine Rs dynamics along postfire successional stands, and (3) to estimate annual soil surface CO2 flux for these ecosystems. Soil surface CO2 flux was significantly affected by soil drainage class (p = 0.014) and stand age (p = 0.006). Soil surface CO2 flux was positively correlated to soil temperature (R2 = 0.78, p < 0.001), but different models were required for each drainage class × aged stand combination. Soil surface CO2 flux was significantly greater at the well‐drained than the poorly drained stands (p = 0.007) during growing season. Annual soil surface CO2 flux for the 1998, 1995, 1989, 1981, 1964, 1930, and 1870 burned stands averaged 226, 412, 357, 413, 350, 274, and 244 g C m‐2 yr−1 in the well‐drained stands and 146, 380, 300, 303, 256, 233, and 264 g C m−2 yr−1 in the poorly drained stands. Soil surface CO2 flux during the winter (from 1 November to 30 April) comprised from 5 to 19% of the total annual Rs. We speculate that the smaller soil surface CO2 flux in the recently burned than the older stands is mainly caused by decreased root respiration.}, number={D3}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Wang, CK and Bond-Lamberty, B and Gower, ST}, year={2002}, month={Dec} }
 @article{brye_norman_gower_2002, title={The fate of nutrients following three- and six-year burn intervals in a tallgrass prairie restoration in Wisconsin}, volume={148}, ISSN={["1938-4238"]}, DOI={10.1674/0003-0031(2002)148[0028:tfonft]2.0.co;2}, abstractNote={Abstract Prescribed burning recycles essential plant nutrients and stimulates growth in prairie restoration. While reducing the content of nutrients in dry matter, prescribed burning may also alter the spatial variability and distribution of nutrients, which in turn could negatively impact long-term productivity. A study was conducted in a tallgrass prairie restoration at the Audubon Society's Goose Pond Sanctuary near Arlington, Wisconsin to characterize the content and spatial variability and distribution of macro- (i.e., N, C, P, K, Ca, Mg and S) and micro-nutrients (i.e., Zn, B, Mn, Cu, Fe, Al and Na) in the aboveground litter before burning and in the ash after burning following 3- and 6-y burn intervals. Aboveground litter mass was significantly higher in 2001 after the 3-y burn interval than in 1998 after the 6-y burn interval. The amount of preburn litter was consistently reduced by >90% for both burn intervals, but the reduction of dry matter and the reductions in mass of N, C, P, K and S were significantly higher in 2001 than in 1998. The 6-y burn interval resulted in nutrient export that was similar to nutrient inputs from atmospheric wet deposition, whereas the 3-y burn interval resulted in the export of N, K, Ca and Mg faster than they were replenished. Prescribed burning significantly affected the spatial variability of dry matter and the concentration and content of most macro- and micronutrients. However, prescribed burning had little effect on the pre- and postburn spatial distributions of macro- and micro-nutrient masses, which were similar to pre- and postburn spatial distributions of litter and ash masses, except for Fe and Al which had atypically large concentration variances.}, number={1}, journal={AMERICAN MIDLAND NATURALIST}, author={Brye, KR and Norman, JM and Gower, ST}, year={2002}, month={Jul}, pages={28–42} }
 @article{ewers_mackay_gower_ahl_burrows_samanta_2002, title={Tree species effects on stand transpiration in northern Wisconsin}, volume={38}, ISSN={["1944-7973"]}, DOI={10.1029/2001wr000830}, abstractNote={We quantified canopy transpiration (EC) using sap flux measurements representing the four major forest types (northern hardwoods, conifer, aspen/fir, and forested wetland) around the WLEF‐TV tall tower in northern Wisconsin. In order to scale individual sap flux measurements to EC, we quantified the amount of sapwood area per unit ground area and the spatial distribution of sap flux within trees. Contrary to our hypothesis that all tree species would have the same positive relationship between tree diameter and sapwood depth, white cedar and speckled alder, both wetland species, showed no relationship. We also hypothesized that the conifer trees would have a lower whole tree hydraulic conductance than deciduous trees. We actually discovered that white cedar had the highest hydraulic conductance. Our third hypothesis, that sapwood area per unit ground area would determine stand EC, was not rejected. The resulting average daily EC values over 53 days (23 June to 16 August 2000) from combining sap flux and sapwood area per unit ground area were 1.4, 0.8, 2.1, and 1.4 mm d−1 for conifer, northern hardwoods, aspen/fir, and forested wetland cover types, respectively. Average daily EC was only explained by an exponential saturation with daily average vapor pressure deficit.}, number={7}, journal={WATER RESOURCES RESEARCH}, author={Ewers, BE and Mackay, DS and Gower, ST and Ahl, DE and Burrows, SN and Samanta, SS}, year={2002}, month={Jul} }
 @article{bisbee_gower_norman_nordheim_2001, title={Environmental controls on ground cover species composition and productivity in a boreal black spruce forest}, volume={129}, ISSN={["0029-8549"]}, DOI={10.1007/s004420100719}, abstractNote={Boreal black spruce forests typically have a dense ground cover of bryophytes. The two main bryophyte groups in boreal black spruce forests, feathermoss and Sphagnum, have ecophysiological characteristics that influence the biogeochemical cycles of black spruce forests differently. The objective of this study was to examine the environmental controls of ground cover composition and net primary production (NPP) of feathermoss and Sphagnum in a boreal black spruce forest in central Saskatchewan. The fraction of Sphagnum ground cover was positively correlated to canopy photosynthetically active radiation (PAR) transmittance (r  2 =0.48, P=0.03), but the fraction of feathermoss ground cover was negatively correlated to canopy PAR transmittance in plots where Sphagnum was present (r  2 =0.87, P<0.0001). Sphagnum presence was inversely correlated (P=0.0001) to water table index, defined as water table depth relative to the peat layer, while feathermoss occurred in a wider range of microenvironments. Average NPP for 1998 was more than three times greater for Sphagnum (77 g C m -2  year -1 ) than feathermoss (24 g C m -2  year -1 ), but the average bryophyte NPP for 1998 was 25 g C m -2  year -1  because feathermoss was the dominant ground cover. The large, but differing, peat carbon content of Sphagnum- versus feathermoss-dominated boreal forests and peatlands necessitates the need to accurately quantify fraction ground cover. Additional validation of the empirical models between environmental variables and fraction ground cover of bryophytes is necessary, but the reported relationships offer an approach to model carbon dynamics of bryophytes in boreal forests and peatlands.}, number={2}, journal={OECOLOGIA}, author={Bisbee, KE and Gower, ST and Norman, JM and Nordheim, EV}, year={2001}, month={Oct}, pages={261–270} }
 @article{kucharik_brye_norman_foley_gower_bundy_2001, title={Measurements and modeling of carbon and nitrogen cycling in agroecosystems of southern Wisconsin: Potential for SOC sequestration during the next 50 years}, volume={4}, DOI={10.1007/s10021-001-0007-2}, number={3}, journal={Ecosystems}, author={Kucharik, C. J. and Brye, K. R. and Norman, J. M. and Foley, J. A. and Gower, S. T. and Bundy, L. G.}, year={2001}, pages={237–258} }
 @article{gower_krankina_olson_apps_linder_wang_2001, title={Net primary production and carbon allocation patterns of boreal forest ecosystems}, volume={11}, DOI={10.2307/3060928}, abstractNote={The three objectives of this paper were: to summarize net primary production (NPP) and carbon allocation patterns for boreal forests, to examine relationships between climatic and biological variables and NPP, and to examine carbon allocation coefficients for all boreal forests or types of boreal forests that can be used to estimate NPP from easily measured components of NPP. Twenty-four Class I stands (complete NPP budgets) and 45 Class II boreal forest stands (aboveground NPP [NPPA] and budget only) were identified. The geographic distribution of the Class I stands was not uniform; 46% of the stands were from two studies in North America, and only one stand was from the important larch forests of Eurasia. Total (above- and belowground) net primary production (NPPT) ranged from 52 to 868 g C·m−2·yr−1 and averaged 424 g C·m−2·yr−1. NPPA was consistently larger for deciduous than for evergreen boreal forests in each of the major boreal regions, especially for boreal forests in Alaska. Belowground net primary production:total net primary production (NPPB : NPPT) ratios were consistently larger for evergreen (0.36) than deciduous (0.19) boreal forests. NPP of different-aged stands in age sequence varied from 44% to 77%, a magnitude equal to or greater than that of climatic factors or vegetation type. NPP and NPPA were positively correlated (r2 = 0.66–0.68) to mean annual aboveground increment for Class I stands, and this empirical relationship explained 81% of the observed variation of NPPA for Class II stands. These robust relationships provide an approach for increasing the number and spatial coverage of boreal forest NPP data needed to evaluate NPP estimates from ecosystem models. Notable deficiencies of boreal forest NPP data were ground layer vegetation and belowground NPP data, NPP data for boreal forest age sequences, and NPP data for boreal larch ecosystems in Eurasia.}, number={5}, journal={Ecological Applications}, author={Gower, S. T. and Krankina, O. and Olson, R. J. and Apps, M. and Linder, S. and Wang, C.}, year={2001}, pages={1395–1411} }
 @article{brye_norman_bundy_gower_2001, title={Nitrogen and carbon leaching in agroecosystems and their role in denitrification potential}, volume={30}, ISSN={["0047-2425"]}, DOI={10.2134/jeq2001.30158x}, abstractNote={ABSTRACT}, number={1}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Brye, KR and Norman, JM and Bundy, LG and Gower, ST}, year={2001}, pages={58–70} }
 @article{whitehead_gower_2001, title={Photosynthesis and light-use efficiency by plants in a Canadian boreal forest ecosystem}, volume={21}, ISSN={["0829-318X"]}, DOI={10.1093/treephys/21.12-13.925}, abstractNote={Measurements of the photosynthetic response to midsummer irradiance were made for 11 species representing the dominant trees, understory shrubs, herbaceous plants and moss species in an old black spruce (Picea mariana (Mill.) B.S.P.) boreal forest ecosystem. Maximum rates of photosynthesis per unit foliage area at saturating irradiance, A(max), were highest for aspen (Populus tremuloides Michx.), reaching 16 micromol m(-2) s(-1). For tamarack (Larix laricina (Du Roi) K. Kock) and P. mariana, Amax was only 2.6 and 1.8 micromol m(-2) s(-1), respectively. Values of A(max) for understory shrubs and herbaceous plants were clustered between 9 and 11 micromol m(-2) s(-1), whereas A(max) of feather moss (Pleurozium schreberi (Brid.) Mitt.) reached only 1.9 micromol m(-2) s(-1). No corrections were made for differences in shoot structure, but values of photosynthetic light-use efficiency were similar for most species (70-80 mmol CO2 mol(-1)); however, they were much lower for L. laricina and P. mariana (15 mmol CO2 mol(-1)) and much higher for P. schreberi (102 m;mol CO2 mol(-1)). There was a linear relationship between Amax and foliage nitrogen concentration on an area basis for the broad-leaved species in the canopy and understory, but the data for P. mariana, L. laricina and P. schreberi fell well below this line. We conclude that it is not possible to scale photosynthesis from leaves to the canopy in this ecosystem based on a single relationship between photosynthetic rate and foliage nitrogen concentration.}, number={12-13}, journal={TREE PHYSIOLOGY}, author={Whitehead, D and Gower, ST}, year={2001}, month={Aug}, pages={925–929} }
 @article{wang_gower_wang_zhao_yan_bond-lamberty_2001, title={The influence of fire on carbon distribution and net primary production of boreal Larix gmelinii forests in north-eastern China}, volume={7}, ISSN={["1365-2486"]}, DOI={10.1046/j.1354-1013.2001.00441.x}, abstractNote={Abstract}, number={6}, journal={GLOBAL CHANGE BIOLOGY}, author={Wang, CK and Gower, ST and Wang, YH and Zhao, HX and Yan, P and Bond-Lamberty, BP}, year={2001}, month={Aug}, pages={719–730} }
 @article{canadell_mooney_baldocchi_berry_ehleringer_field_gower_hollinger_hunt_jackson_et al._2000, title={Carbon metabolism of the terrestrial biosphere: A multitechnique approach for improved understanding}, volume={3}, ISSN={["1435-0629"]}, DOI={10.1007/s100210000014}, number={2}, journal={ECOSYSTEMS}, author={Canadell, JG and Mooney, HA and Baldocchi, DD and Berry, JA and Ehleringer, JR and Field, CB and Gower, ST and Hollinger, DY and Hunt, JE and Jackson, RB and et al.}, year={2000}, pages={115–130} }
 @article{campbell_gower_2000, title={Detritus production and soil N transformations in old-growth eastern hemlock and sugar maple stands}, volume={3}, ISSN={["1432-9840"]}, DOI={10.1007/s100210000018}, number={2}, journal={ECOSYSTEMS}, author={Campbell, JL and Gower, ST}, year={2000}, pages={185–192} }
 @article{kloeppel_gower_vogel_reich_2000, title={Leaf-level resource use for evergreen and deciduous conifers along a resource availability gradient}, volume={14}, ISSN={["0269-8463"]}, DOI={10.1046/j.1365-2435.2000.00439.x}, abstractNote={Abstract}, number={3}, journal={FUNCTIONAL ECOLOGY}, author={Kloeppel, BD and Gower, ST and Vogel, JG and Reich, PB}, year={2000}, month={Jun}, pages={281–292} }
 @article{gower_hunter_campbell_vogel_veldhuis_harden_trumbore_norman_kucharik_2000, title={Nutrient dynamics of the southern and northern BOREAS boreal forests}, volume={7}, ISSN={["1195-6860"]}, DOI={10.1080/11956860.2000.11682620}, abstractNote={Abstract The objective of this study was to compare nutrient concentration, distribution, and select components of nutrient budgets for aspen (Populus tremuloides), jack pine (Pinus banksiana), and black spruce (Picea mariana) forest ecosystems at the BOReal Ecosystem Atmosphere Study (BOREAS), southern and northern study areas near Candle Lake, Saskatchewan and Thompson, Manitoba, Canada, respectively. The vegetation (excluding fine roots and understory) in the aspen, black spruce, and jack pine stands contained 70-79%, 53-54%, and 58-67% of total ecosystem carbon content, respectively. Soil (forest floor and mineral soil) nitrogen (N), calcium (Ca), and magnesium (Mg) content comprised over 90% of the total ecosystem nutrient content, except for Ca and Mg content of the southern black spruce stand and Ca content of the southern aspen stand which were less than 90%. Annual litterfall N content was significantly greater (p < 0.05) for trembling aspen (30-41 kg N ha-1 yr-1) than for jack pine (5-10 kg N ha-1 yr-1) or black spruce (6-7 kg N ha-1 yr-1), and was generally greater, but not significantly, for the southern than for the northern study area. Aboveground net primary production was positively correlated (R2 = 0.91) to annual litterfall N content for the BOREAS forests, and for all boreal forests (R2 = 0.57). Annual aboveground nutrient (N, Ca, Mg, and K) requirements (sum of the annual increment of nutrient in foliage, branches, and stems) were significantly greater (p < 0.05) for trembling aspen than for jack pine or black spruce forests. Annual aboveground N requirements ranged from 37-53, 6-14, and 6-7 kg N ha-1 yr-1 for trembling aspen, jack pine, and black spruce forests, respectively. The greater nutrient requirements of deciduous than evergreen boreal forests was explained by a greater annual production of biomass and lower use efficiency of nutrients. Nutrient cycling characteristics of boreal forests were influenced by climate and forest type, with the latter having a greater influence on litterfall N, annual nutrient requirements, nutrient mean residence time, and nutrient distribution.}, number={4}, journal={ECOSCIENCE}, author={Gower, ST and Hunter, A and Campbell, J and Vogel, J and Veldhuis, H and Harden, J and Trumbore, S and Norman, JM and Kucharik, CJ}, year={2000}, pages={481–490} }
 @misc{kucharik_foley_delire_fisher_coe_lenters_young-molling_ramankutty_norman_gower_2000, title={Testing the performance of a Dynamic Global Ecosystem Model: Water balance, carbon balance, and vegetation structure}, volume={14}, ISSN={["1944-9224"]}, DOI={10.1029/1999gb001138}, abstractNote={While a new class of Dynamic Global Ecosystem Models (DGEMs) has emerged in the past few years as an important tool for describing global biogeochemical cycles and atmosphere‐biosphere interactions, these models are still largely untested. Here we analyze the behavior of a new DGEM and compare the results to global‐scale observations of water balance, carbon balance, and vegetation structure. In this study, we use version 2 of the Integrated Biosphere Simulator (IBIS), which includes several major improvements and additions to the prototype model developed by Foley et al. [1996]. IBIS is designed to be a comprehensive model of the terrestrial biosphere; the model represents a wide range of processes, including land surface physics, canopy physiology, plant phenology, vegetation dynamics and competition, and carbon and nutrient cycling. The model generates global simulations of the surface water balance (e.g., runoff), the terrestrial carbon balance (e.g., net primary production, net ecosystem exchange, soil carbon, aboveground and belowground litter, and soil CO2 fluxes), and vegetation structure (e.g., biomass, leaf area index, and vegetation composition). In order to test the performance of the model, we have assembled a wide range of continental and global‐scale data, including measurements of river discharge, net primary production, vegetation structure, root biomass, soil carbon, litter carbon, and soil CO2 flux. Using these field data and model results for the contemporary biosphere (1965–1994), our evaluation shows that simulated patterns of runoff, NPP, biomass, leaf area index, soil carbon, and total soil CO2 flux agree reasonably well with measurements that have been compiled from numerous ecosystems. These results also compare favorably to other global model results.}, number={3}, journal={GLOBAL BIOGEOCHEMICAL CYCLES}, author={Kucharik, CJ and Foley, JA and Delire, C and Fisher, VA and Coe, MT and Lenters, JD and Young-Molling, C and Ramankutty, N and Norman, JM and Gower, ST}, year={2000}, month={Sep}, pages={795–825} }
 @article{harden_trumbore_stocks_hirsch_gower_kp o'neill_kasischke_2000, title={The role of fire in the boreal carbon budget}, volume={6}, ISSN={["1365-2486"]}, DOI={10.1046/j.1365-2486.2000.06019.x}, abstractNote={Summary}, journal={GLOBAL CHANGE BIOLOGY}, author={Harden, JW and Trumbore, SE and Stocks, BJ and Hirsch, A and Gower, ST and KP O'Neill and Kasischke, ES}, year={2000}, month={Dec}, pages={174–184} }
 @article{brye_norman_bundy_gower_2000, title={Water-budget evaluation of prairie and maize ecosystems}, volume={64}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj2000.642715x}, abstractNote={Annual monitoring of water‐budget components is useful for comparing the fate of water inputs among ecosystems. Land‐use changes from natural prairies to managed agroecosystems alter water‐budget components. Weekly hydrological budgets for a restored natural prairie and maize (Zea mays L.) agroecosystems (no‐tillage and chisel‐plow) were constructed for 132 consecutive wk between June 1995 and January 1998. Precipitation, drainage, soil water–storage changes, and snow‐cover changes were measured on Plano silt loam soil (fine‐silty, mixed, superactive, mesic Typic Argiudoll) at agricultural and prairie sites. Compared with the maize ecosystems, the prairie maintained greater soil water contents deeper in the soil profile (0.8–1.4 m), somewhat larger evapotranspiration (Et), and significantly less drainage because of considerable interception of precipitation by a residue layer. Soil water storage in the no‐tillage maize setting was more similar to the prairie, while Et, net primary productivity, and drainage were more comparable to the chisel‐plow agroecosystem. Total drainage measured with equilibrium‐tension lysimeters was 199 mm of water (coefficient of variation [CV] = 5.7%) for the prairie ecosystem, 563 mm of water (CV = 13.6%) for the no‐tillage maize ecosystem, and 793 mm of water (CV = 18.5%) for the chisel‐plow maize ecosystem. Residue interception for the prairie was 477 mm, compared with 681 mm of precipitation during the growing season of 1997, which contributed to lower prairie drainage. The combination of similar productivity, higher soil water contents, and less drainage than the chisel‐plow ecosystem suggests that a no‐tillage ecosystem is more sustainable than the chisel‐plow agroecosystem in terms of reducing potential adverse environmental impacts associated with soil water movement.}, number={2}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Brye, KR and Norman, JM and Bundy, LG and Gower, ST}, year={2000}, pages={715–724} }
 @article{running_baldocchi_turner_gower_bakwin_hibbard_1999, title={A global terrestrial monitoring network integrating tower fluxes, flask sampling, ecosystem modeling and EOS satellite data}, volume={70}, ISSN={["0034-4257"]}, DOI={10.1016/s0034-4257(99)00061-9}, abstractNote={Accurate monitoring of global scale changes in the terrestrial biosphere has become acutely important as the scope of human impacts on biological systems and atmospheric chemistry grows. For example, the Kyoto Protocol of 1997 signals some of the dramatic socioeconomic and political decisions that may lie ahead concerning CO2 emissions and global carbon cycle impacts. These decisions will rely heavily on accurate measures of global biospheric changes Schimel 1998, IGBP TCWG 1998. An array of national and international programs have inaugurated global satellite observations, critical field measurements of carbon and water fluxes, and global model development for the purposes of beginning to monitor the biosphere. The detection by these programs of interannual variability of ecosystem fluxes and of longer term trends will permit early indication of fundamental biospheric changes which might otherwise go undetected until major biome conversion begins. This article describes a blueprint for more comprehensive coordination of the various flux measurement and modeling activities into a global terrestrial monitoring network that will have direct relevance to the political decision making of global change.}, number={1}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Running, SW and Baldocchi, DD and Turner, DP and Gower, ST and Bakwin, PS and Hibbard, KA}, year={1999}, month={Oct}, pages={108–127} }
 @article{brye_norman_bundy_gower_1999, title={An equilibrium tension lysimeter for measuring drainage through soil}, volume={63}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj1999.03615995006300030016x}, abstractNote={An equilibrium tension lysimeter (ETL) was designed to maintain equilibrium between lysimeter suction and soil matric potential. Equilibrium tension lysimeter replicates were installed in a natural prairie, and N-fertilized no-tillage and chisel-plow agroecosystems to measure drainage through undisturbed soil. The ETLs were used to monitor drainage continuously at 1,4 m below the soil surface through a 0.2-μm pore diameter stainless steel porous plate (0.19 m 2 ). Heat dissipation sensors were used to record variations in matric potential inside and outside the ETL's sampling area. Suction was maintained on lysimeters according to the matric potential experienced by the surrounding bulk soil. Cumulative lysimeter drainage was 199, 563, and 793 mm for the prairie, fertilized no-tillage, and fertilized chisel-plow agroecosystems for 132 wk between 25 June 1995 and 3 Jan. 1998. Drainage accounted for 11, 31, and 44% of precipitation inputs for the prairie, fertilized no-tillage, and fertilized chisel plow systems. Variability between lysimeter replicates was smallest for the prairie, where the coefficient of variation (CV) was 8.2%, and largest for the N-fertilized no-tillage agroecosystem (CV = 36.6%).}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Brye, KR and Norman, JM and Bundy, LG and Gower, ST}, year={1999}, pages={536–543} }
 @article{kucharik_norman_gower_1999, title={Characterization of radiation regimes in nonrandom forest canopies: Theory, measurements, and a simplified modeling approach}, volume={19}, DOI={10.1093/treephys/19.11.695}, abstractNote={We used field measurements and Monte Carlo simulations of canopy gap-size distribution and gap fraction to examine how beam radiation interacts with clumped boreal forest canopies of aspen (Populus tremuloides Michx.), black spruce (Picea mariana (Mill.) B.S.P.) and jack pine (Pinus banksiana Lamb.). We demonstrate that the Beer-Lambert law can be modified to accommodate transmission of radiation through a clumped forest canopy as a function of path length or sun zenith angle. Multiband Vegetation Imager (MVI) measurements and Monte Carlo simulations showed that values of the zenith element clumping index (Omega(e)(0)) are typically between 0.4 and 0.5 in jack pine and black spruce and 0.65 in aspen. Estimates of LAI obtained from MVI measurements of the canopy gap fraction and adjusted for canopy clumping and branch architecture yielded LAI values of 3.0 in jack pine, 3.3 in aspen, and about 6.0 in black spruce. These LAI estimates were within 10-25% of direct measurements made at the same sites. Data obtained with the MVI, along with numerical simulations, demonstrated that assumptions of random foliage distributions in boreal forests are invalid and could yield erroneous values of LAI measured by indirect techniques and false characterizations of atmosphere-biosphere interactions. Monte Carlo simulations were used to develop a general equation for beam radiation penetration as a function of zenith angle in clumped canopies. The essential measurements included stem spacing, crown diameter, crown depth, and within-crown gap fraction.}, number={11}, journal={Tree Physiology}, author={Kucharik, C. J. and Norman, J. M. and Gower, S. T.}, year={1999}, pages={695–706} }
 @article{fassnacht_gower_1999, title={Comparison of the litterfall and forest floor organic matter and nitrogen dynamics of upland forest ecosystems in north central Wisconsin}, volume={45}, DOI={10.1007/bf00993003}, number={3}, journal={Biogeochemistry}, author={Fassnacht, K. S. and Gower, S. T.}, year={1999}, pages={265–284} }
 @misc{gower_kucharik_norman_1999, title={Direct and indirect estimation of leaf area index, f(APAR), and net primary production of terrestrial ecosystems}, volume={70}, ISSN={["1879-0704"]}, DOI={10.1016/s0034-4257(99)00056-5}, abstractNote={A primary objective of the Earth Observing System (EOS) is to develop and validate algorithms to estimate leaf area index (L), fraction of absorbed photosynthetically active radiation (fAPAR), and net primary production (NPP) from remotely sensed products. These three products are important because they relate to or are components of the metabolism of the biosphere and can be determined for terrestrial ecosystems from satellite-borne sensors. The importance of these products in the EOS program necessitates the need to use standard methods to obtain accurate ground truth estimates of L, fAPAR, and NPP that are correlated to satellite-derived estimates. The objective of this article is to review direct and indirect methods used to estimate L, fAPAR, and NPP in terrestrial ecosystems. Direct estimates of L, biomass, and NPP can be obtained by harvesting individual plants, developing allometric equations, and applying these equations to all individuals in the stand. Using non-site-specific allometric equations to estimate L and foliage production can cause large errors because carbon allocation to foliage is influenced by numerous environmental and ecological factors. All of the optical instruments that indirectly estimate L actually estimate “effective” leaf area index (LE) and underestimate L when foliage in the canopy is nonrandomly distributed (i.e., clumped). We discuss several methods, ranging from simple to complex in terms of data needs, that can be used to correct estimates of L when foliage is clumped. Direct estimates of above-ground and below-ground net primary production (NPPA and NPPB, respectively) are laborious, expensive and can only be carried out for small plots, yet there is a great need to obtain global estimates of NPP. Process models, driven by remotely sensed input parameters, are useful tools to examine the influence of global change on the metabolism of terrestrial ecosystems, but an incomplete understanding of carbon allocation continues to hamper development of more accurate NPP models. We summarize carbon allocation patterns for major terrestrial biomes and discuss emerging allocation patterns that can be incorporated into global NPP models. One common process model, light use efficiency or epsilon model, uses remotely sensed fAPAR, light use efficiency (LUE) and carbon allocation coefficients, and other meteorological data to estimates NPP. Such models require reliable estimates of LUE. We summarize the literature and provide LUE coefficients for the major biomes, being careful to correct for inconsistencies in radiation, dry matter and carbon allocation units.}, number={1}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Gower, ST and Kucharik, CJ and Norman, JM}, year={1999}, month={Oct}, pages={29–51} }
 @article{vogel_gower_1998, title={Carbon and nitrogen dynamics of boreal jack pine stands with and without a green alder understory}, volume={1}, ISSN={["1432-9840"]}, DOI={10.1007/s100219900032}, number={4}, journal={ECOSYSTEMS}, author={Vogel, JG and Gower, ST}, year={1998}, pages={386–400} }
 @article{fassnacht_gower_1998, title={Comparison of soil and vegetation characteristics of six upland forest habitat types in north central Wisconsin}, volume={15}, number={2}, journal={Northern Journal of Applied Forestry}, author={Fassnacht, K. S. and Gower, S. T.}, year={1998}, pages={69–76} }
 @article{arneth_kelliher_gower_scott_byers_mcseveny_1998, title={Environmental variables regulating soil carbon dioxide efflux following clear-cutting of a Pinus radiata D. Don plantation}, volume={103}, ISSN={["2169-897X"]}, DOI={10.1029/97jd03464}, abstractNote={The regulation of soil surface CO2 efflux (Fs) from a dryland Pinus radiata clear‐cut in New Zealand (658‐mm annual rainfall, 50‐mm soil water storage over 0.5‐m depth of soil) was quantified using a multiplicative, soil moisture and temperature constraint model. Model parameters were determined from measurements of Fs by eddy covariance and by two portable CO2 analyzers equipped with soil chambers during 8 consecutive days in November 1995. Fs from the two chamber systems agreed consistently, but agreement between chamber and eddy covariance measurements was confined to a very small flux‐range (1.5–2.5 μmol m−2 s−1). When the soil surface was wet and wind speed (u, a surrogate for static pressure fluctuations) was high, eddy covariance fluxes were >3 μmol m−2 s−1 (maximum 5.0 m−2 s−1), significantly higher than the chamber values. Including u as a third constraint in the model facilitated good predictions of Fs over the entire range of environmental conditions. Daily Fs during the study period ranged from 0.8 to 2.9 g C m−2. Driven by weather data from the forest fire station and subroutines for soil water balance and temperature, modeled Fs for the year ending in June 1996 was 0.37 kg C m−2. This year had below average (547 mm) rainfall. For a year with 640‐mm rainfall, a significant increase of annual Fs (0.44 kg C m−2) demonstrated the severe restriction of soil microbial activity by moisture deficit at dryland sites. Moreover, when the soil was adequately watered, Fs was frequently restricted by low wind speed.}, number={D5}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Arneth, A and Kelliher, FM and Gower, ST and Scott, NA and Byers, JN and McSeveny, TM}, year={1998}, month={Mar}, pages={5695–5705} }
 @article{kloeppel_gower_treichel_kharuk_1998, title={Foliar carbon isotope discrimination in Larix species and sympatric evergreen conifers: a global comparison}, volume={114}, ISSN={["1432-1939"]}, DOI={10.1007/s004420050431}, abstractNote={Larches (Larix spp.), deciduous conifers, occur in the northern hemisphere in cold-temperate and boreal climates - an environment normally thought to favor evergreen tree species. We compare foliar carbon isotope discrimination (Δ), instantaneous water use efficiency, total foliar nitrogen concentration, and specific leaf area (for a subset of sites) between Larix spp. and co-occurring evergreen conifers at 20 sites throughout the natural range of larches. Except for Larix occidentalis in the xeric Intermountain West, USA, Δ is significantly (P < 0.05) greater for larches than co-occurring evergreen conifers at 77% of the sites, suggesting that larches use water less efficiently. At elevations greater than 3000 m, the Δ of Larix spp. and co-occurring conifers converge, suggesting that water is not the limiting resource. Foliar nitrogen concentration and specific leaf area are two ecophysiological characteristics that are positively correlated with high photosynthetic capacity. Foliar nitrogen concentration is significantly greater for larches than evergreen conifers at 88% of the sites and specific leaf area is approximately three times greater for larches than co-occurring conifers. Future studies should examine the potential effect that global warming may have on the distribution of larch forests because the water use efficiency of larches is commonly less than co-occurring evergreen conifers and the boreal and high-latitude environments are likely to experience the greatest climate warming.}, number={2}, journal={OECOLOGIA}, author={Kloeppel, BD and Gower, ST and Treichel, IW and Kharuk, S}, year={1998}, month={Apr}, pages={153–159} }
 @article{wagai_brye_gower_norman_bundy_1998, title={Land use and environmental factors influencing soil surface CO2 flux and microbial biomass in natural and managed ecosystems in southern Wisconsin}, volume={30}, ISSN={["0038-0717"]}, DOI={10.1016/s0038-0717(98)00041-8}, abstractNote={Many of the native prairies in southern Wisconsin, and the midwestern United States in general, have been replaced by conventional till (chisel plow) and no-tillage corn agroecosystems. However, knowledge of the influence of land use change on the structure and function of ecosystems is incomplete. Soil surface CO2 flux is a major transfer of carbon from terrestrial ecosystems to the atmosphere and varies greatly among vegetation types. We measured soil surface CO2 flux and microbial biomass in tilled and no-till corn agroecosystems and a restored prairie ecosystem, examined the influence of various environmental factors on soil surface CO2 flux in these ecosystems, and estimated annual soil surface CO2 flux for the natural and managed ecosystems. Soil surface CO2 flux is significantly greater for prairie and conventional tilled corn than for no-till corn in the spring, greater for prairie than tilled and no-till corn from July to early October, and is similar for all three ecosystems in the late fall and winter. Soil surface CO2 flux is positively correlated to soil temperature at 10 cm for all three ecosystems (r2=0.43–0.60, P<0.001), but is only weakly correlated to soil moisture. Using an empirical model to estimate soil surface CO2 flux from 10 cm soil temperatures, we estimate annual soil surface CO2 fluxes of 508, 535 and 719 (g C m−2 y−1) for the tilled and no-till corn and restored prairie ecosystems, respectively, demonstrating that land use practices significantly affect soil surface CO2 flux.}, number={12}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Wagai, R and Brye, KR and Gower, ST and Norman, JM and Bundy, LG}, year={1998}, month={Oct}, pages={1501–1509} }
 @article{kucharik_norman_gower_1998, title={Measurements of branch area and adjusting leaf area index indirect measurements}, volume={91}, ISSN={["0168-1923"]}, DOI={10.1016/s0168-1923(98)00064-1}, abstractNote={Estimates of leaf area index obtained with indirect measurement techniques, which are replacing more arduous destructive sampling methods, are frequently questioned due to light interception by woody elements and a non-random distribution of foliage elements. Usually, branches are assumed to be positioned randomly with respect to leaves or shoots in the canopy. However, in this study of boreal forest architecture, branches are shown to be preferentially shaded by other non-woody elements (e.g. shoots or leaves) in both coniferous and deciduous species of the boreal region. A new instrument called a Multiband Vegetation Imager (MVI) is used to capture two-band (Visible, 400–620 nm and Near-Infrared, 720–950 nm) image pairs of contrasting Canadian boreal forest canopies during the BOReal Ecosystem-Atmosphere Study (BOREAS). The spatial relationship of branches and photosynthetically active foliage is studied to estimate the fraction of the effective branch hemi-surface area index (Be) that is masked by leaves and shoots. We suggest an approach that corrects indirect LAI measurements using the LAI-2000 or a similar instrument by correcting for the following biases: (1) the effective canopy branch hemi-surface area that is not masked by leaves or shoots in the canopy, (2) the amount of stem hemi-surface area beneath crowns, (3) leaf (or shoot) (Ωe(θ)) and branch (Ωb(θ)) non-random spatial distributions in the canopy, and (4) the fraction of maximum LAI resulting from defoliation in the canopy. In boreal aspen, MVI image analysis shows that 95% of the effective branch hemi-surface area is masked by other foliage in the canopy. In jack pine and black spruce forests, 80–90% of the effective branch hemi-surface area is masked by other foliage in the canopy. These estimates suggest the fraction of indirect LAI that consists of branches intercepting light is less than 10%. Therefore, branches generally do not intercept a significant amount of beam radiation in boreal forests, and do not significantly bias indirect LAI measurements. However, stems, which comprise 30–50% of the total woody area in this study, may not be preferentially shaded by leafy foliage. Therefore, stem contribution to indirect LAI estimates measured with the LAI-2000 or a similar instrument cannot be overlooked. MVI estimates of the total branch hemi-surface area index agree to within 10–40% of direct measurements made in similar species; however, the error between indirect and direct measurements may be due largely to difficulties associated with obtaining adequate sampling so that the error may fall within the noise level of measurements.}, number={1-2}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Kucharik, CJ and Norman, JM and Gower, ST}, year={1998}, month={May}, pages={69–88} }
 @article{kucharik_norman_gower_1998, title={Measurements of leaf orientation, light distribution and sunlit leaf area in a boreal aspen forest}, volume={91}, ISSN={["0168-1923"]}, DOI={10.1016/s0168-1923(98)00058-6}, abstractNote={A new instrument called a Multiband Vegetation Imager (MVI) (Kucharik et al., 1997), which uses a 16-bit charge-coupled device (CCD) camera and filter exchange mechanism to capture 2-band (visible and near-infrared) image pairs of plant canopies, has been used to measure the light distribution over sunlit leaves and indirectly infer leaf area index (LAI), sunlit LAI and leaf angle distribution (LAD) in a boreal aspen (Populus tremuloides) forest during the Boreal Ecosystem–Atmosphere Study (BOREAS). One purpose of this study is to demonstrate that by combining MVI measurements with numerical Monte Carlo simulations of forest canopy architecture, the LAD and sunlit LAI of aspen can be obtained indirectly. Our results show that this boreal aspen stand exemplifies an erectophile LAD, with a mean leaf inclination angle near 70°. We also find that the values of the measured and modeled sunlit leaf area in aspen do not change dramatically for typical northern boreal latitude solar zenith angles (i.e. 30–70°). A major problem with determining the sunlit LAI is deciding what range of light intensities constitute a sunlit leaf because penumbra create a smooth continuum of light intensities over sunlit and shaded leaves in the canopy. Therefore, we show that the upper and lower limits can be placed on sunlit LAI values in aspen by using different leaf illumination threshold levels to determine sunlit and shaded LAI in the canopy. Typically, sunlit LAI values in aspen (LAI=3.3) range between 0.8–1.0 at a 70° sun zenith angle and 1.1–1.6 at a 30° sun zenith angle. Monte Carlo simulations and MVI measurements suggest that canopy sunlit leaf area estimates are possible from below the canopy at modest LAI values (<∼4.0) but become unreliable in higher LAI (>5.0). Since a substantial fraction of the total sunlit leaf area can be viewed from below the canopy in aspen (40–60% of the total sunlit LAI), a representative light distribution can be measured and used to quantify the canopy leaf angle distribution.}, number={1-2}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Kucharik, CJ and Norman, JM and Gower, ST}, year={1998}, month={May}, pages={127–148} }
 @article{goulden_wofsy_harden_trumbore_crill_gower_fries_daube_fan_sutton_et al._1998, title={Sensitivity of boreal forest carbon balance to soil thaw}, volume={279}, ISSN={["0036-8075"]}, DOI={10.1126/science.279.5348.214}, abstractNote={
            We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 ± 0.5 metric ton of carbon per hectare per year (ton C ha
            −1
            year
            −1
            ) from 1994 to 1997, with a gain of 0.6 ± 0.2 ton C ha
            −1
            year
            −1
            in moss and wood offset by a loss of 0.8 ± 0.5 ton C ha
            −1
            year
            −1
            from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool (∼150 tons C ha
            −1
            ) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site.
          }, number={5348}, journal={SCIENCE}, author={Goulden, ML and Wofsy, SC and Harden, JW and Trumbore, SE and Crill, PM and Gower, ST and Fries, T and Daube, BC and Fan, SM and Sutton, DJ and et al.}, year={1998}, month={Jan}, pages={214–217} }
 @article{norman_kucharik_gower_baldocchi_crill_rayment_savage_striegl_1997, title={A comparison of six methods for measuring soil-surface carbon dioxide fluxes}, volume={102}, ISSN={["2169-8996"]}, DOI={10.1029/97jd01440}, abstractNote={Measurements of soil‐surface CO2 fluxes are important for characterizing the carbon budget of boreal forests because these fluxes can be the second largest component of the budget. Several methods for measuring soil‐surface CO2 fluxes are available: (1) closed‐dynamic‐chamber systems, (2) closed‐static‐chamber systems, (3) open‐chamber systems, and (4) eddy covariance systems. This paper presents a field comparison of six individual systems for measuring soil‐surface CO2 fluxes with each of the four basic system types represented. A single system is used as a reference and compared to each of the other systems individually in black spruce (Picea mariana), jack pine (Pinus banksiana), or aspen (Populus tremuloides) forests. Fluxes vary from 1 to 10 μmol CO2 m−2 s−1. Adjustment factors to bring all of the systems into agreement vary from 0.93 to 1.45 with an uncertainty of about 10–15%.}, number={D24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Norman, JM and Kucharik, CJ and Gower, ST and Baldocchi, DD and Crill, PM and Rayment, M and Savage, K and Striegl, RG}, year={1997}, month={Dec}, pages={28771–28777} }
 @article{ryan_lavigne_gower_1997, title={Annual carbon cost of autotrophic respiration in boreal forest ecosystems in relation to species and climate}, volume={102}, ISSN={["2169-8996"]}, DOI={10.1029/97jd01236}, abstractNote={Autotrophic respiration (Ra) in forest ecosystems can be >50% of the carbon fixed in photosynthesis and may regulate productivity and carbon storage in forest ecosystems, because Ra increases with temperature. We estimated annual Ra from chamber measurements in aspen, black spruce, and jack pine forests in Canada for 1994. Mean foliage respiration at 10°C for expanded leaves was 0.21–0.95 μmol m−2 (leaf surface) s−1 for all species and differed little from May to September. Wood respiration at 15°C (0.2–1 μmol m−2 (stem surface) s−1 for all species) was strongly seasonal, with high rates in midsummer that coincided with wood growth. Fine root respiration at 10°C was 2.5–7.7 μmol kg−1 s−1 for all species and declined throughout the growing season for the conifers. Annual costs of Ra for foliage, wood, and roots (overstory and understory) were 490, 610, and 450 g C m−2 (ground) yr−1 for aspen, black spruce, and jack pine (old) in northern Manitoba and 600, 480, and 310 g C m−2 yr−1 for aspen, black spruce, and jack pine (old) in central Saskatchewan. Carbon use efficiency (CUE), the ratio of net production to production plus Ra, averaged 0.44, 0.34, and 0.39 for aspen, black spruce, and jack pine (old) for all tissues and 0.61, 0.36, and 0.44 for aboveground tissues. Differences in CUE between the northern and the southern sites were small for all species, and CUE did not vary with stand biomass. Species differences in CUE suggest that models assuming a constant CUE across species may poorly estimate production and carbon balance for any given site.}, number={D24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Ryan, MG and Lavigne, MB and Gower, ST}, year={1997}, month={Dec}, pages={28871–28883} }
 @article{sellers_hall_kelly_black_baldocchi_berry_ryan_ranson_crill_lettenmaier_et al._1997, title={BOREAS in 1997: Experiment overview, scientific results, and future directions}, volume={102}, ISSN={["2169-8996"]}, DOI={10.1029/97jd03300}, abstractNote={The goal of the Boreal Ecosystem‐Atmosphere Study (BOREAS) is to improve our understanding of the interactions between the boreal forest biome and the atmosphere in order to clarify their roles in global change. This overview paper describes the science background and motivations for BOREAS and the experimental design and operations of the BOREAS 1994 and BOREAS 1996 field years. The findings of the 83 papers in this journal special issue are reviewed. In section 7, important scientific results of the project to date are summarized and future research directions are identified.}, number={D24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Sellers, PJ and Hall, FG and Kelly, RD and Black, A and Baldocchi, D and Berry, J and Ryan, M and Ranson, KJ and Crill, PM and Lettenmaier, DP and et al.}, year={1997}, month={Dec}, pages={28731–28769} }
 @article{gower_vogel_norman_kucharik_steele_stow_1997, title={Carbon distribution and aboveground net primary production in aspen, jack pine, and black spruce stands in Saskatchewan and Manitoba, Canada}, volume={102}, ISSN={["2169-8996"]}, DOI={10.1029/97jd02317}, abstractNote={The objectives of this study are to (1) characterize the carbon (C) content, leaf area index, and aboveground net primary production (ANPP) for mature aspen, black spruce, and young and mature jack pine stands at the southern and northern Boreal Ecosystem‐Atmosphere Study (BOREAS) areas and (2) compare net primary production and carbon allocation coefficients for the major boreal forest types of the world. Direct estimates of leaf area index, defined as one half of the total leaf surface area, range from a minimum of 1.8 for jack pine forests to a maximum of 5.6 for black spruce forests; stems comprise 5 to 15% of the total overstory plant area. In the BOREAS study, total ecosystem (vegetation plus detritus plus soil) carbon content is greatest in the black spruce forests (445,760–479,380 kg C ha−1), with 87 to 88% of the C in the soil, and is lowest in the jack pine stands (68,370–68,980 kg C ha−1) with a similar distribution of carbon in the vegetation and soil. Forest floor carbon content and mean residence time (MRT) also vary more among forest types in a study area than between study areas for a forest type; forest floor MRT range from 16 to 19 years for aspen stands to 28 to 39 years for jack pine stands. ANPP differs significantly among the mature forests at each of the BOREAS study areas, ranging from a maximum of 3490 to 3520 kg C ha−1 yr−1 for aspen stands to 1170 to 1220 kg C ha−1 yr−1 for jack pine stands. Both net primary production (NPP) and carbon allocation differ between boreal evergreen and deciduous forests in the world, suggesting global primary production models should distinguish between these two forest types. On average, 56% of NPP for boreal forests occurs as detritus and illustrates the need to better understand factors controlling aboveground and below‐ground detritus production in boreal forests.}, number={D24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Gower, ST and Vogel, JG and Norman, JM and Kucharik, CJ and Steele, SJ and Stow, TK}, year={1997}, month={Dec}, pages={29029–29041} }
 @article{kucharik_norman_murdock_gower_1997, title={Characterizing canopy nonrandomness with a multiband vegetation imager (MVI)}, volume={102}, ISSN={["2169-8996"]}, DOI={10.1029/97jd01175}, abstractNote={A new method for measuring plant canopy nonrandomness and other architectural components has been developed using a 16 bit (65535 gray scale levels) charged‐coupled device (CCD) camera that captures images of plant canopies in two wavelength bands. This complete system is referred to as a multiband vegetation imager (MVI). The use of two wavelength bands (visible (VIS) 400–620 nm and near infrared (NIR) 720–950 nm) permits identification of sunlit and shaded foliage, sunlit and shaded branch area, clouds, and blue sky based on the camera's resolution, and the varying spectral properties that scene components have in the two wavelength bands. This approach is different from other canopy imaging methods (such as fish‐eye photography) because it emphasizes measuring the fraction of an image occupied by various scene components (branches, shaded leaves, sunlit leaves) under different sky conditions rather than simply the canopy gap fraction under uniform sky conditions. The MVI has been used during the Boreal Ecosystem‐Atmosphere Study (BOREAS) in aspen (Populus tremuloides) and balsam poplar (Populus balsamifera) to estimate architectural characteristics of each canopy. The leaf area index (LAI), sunlit LAI, and degree of nonrandomness within a canopy are architectural properties that have been measured with the MVI. Using a crown‐based Monte Carlo model for nonrandom canopies, nonrandomness factors are calculated from MVI data using two approaches (gap fraction and gap‐size distribution theories) to correct total and sunlit LAI estimates from indirect methods that assume random foliage distributions. Canopy nonrandomness factors obtained from analyzing the gap‐size distribution in a Monte Carlo model are shown to be a function of path length (angle) through the canopy (Ωe(θ)); thus we suggest that LAI‐2000 indirect measurements of LAI be adjusted with the value of Ωe(θ) at θ=35° because this is the mean angle at which the canopy gap fraction is measured by the LAI‐2000. In this study, values of Ωe(35)=0.69 in an aspen forest. Alternatively, corrections to indirect LAI measurements obtained with the MVI in this study are made using the value of Ωe(0) because the MVI is used to measure the canopy gap‐size distribution and gap fraction within 15° of the zenith. Values of Ωe(0) obtained with the MVI in aspen are typically between 0.55 and 0.65; while in balsam poplar, average values of Ωe(0) are equal to 0.82. This study shows that the MVI provides an attractive indirect measurement technique to obtain accurate estimates of total LAI in aspen. Corrected canopy LAI and direct LAI measurements are greater than indirect estimates based on assuming the foliage to be randomly distributed: In aspen, total LAI is 45% larger (3.3 versus 2.0) and sunlit LAI (40° Sun zenith angle) 10% larger, while in balsam poplar, total LAI is 17% larger (2.3 versus 1.9) and sunlit LAI is only 1% larger. The importance of these clumping characteristics is best appreciated with estimates of canopy net CO2 assimilation derived from scaling leaf photosynthesis versus light relations. Aspen canopy assimilation accounting for clumping is 39% larger than estimates based on indirect measurements of total LAI and the assumption that foliage is randomly distributed.}, number={D24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Kucharik, CJ and Norman, JM and Murdock, LM and Gower, ST}, year={1997}, month={Dec}, pages={29455–29473} }
 @article{lavigne_ryan_anderson_baldocchi_crill_fitzjarrald_goulden_gower_massheder_mccaughey_et al._1997, title={Comparing nocturnal eddy covariance measurements to estimates of ecosystem respiration made by scaling chamber measurements at six coniferous boreal sites}, volume={102}, ISSN={["2169-8996"]}, DOI={10.1029/97jd01173}, abstractNote={During the growing season, nighttime ecosystem respiration emits 30–100% of the daytime net photosynthetic uptake of carbon, and therefore measurements of rates and understanding of its control by the environment are important for understanding net ecosystem exchange. Ecosystem respiration can be measured at night by eddy covariance methods, but the data may not be reliable because of low turbulence or other methodological problems. We used relationships between woody tissue, foliage, and soil respiration rates and temperature, with temperature records collected on site to estimate ecosystem respiration rates at six coniferous BOREAS sites at half‐hour or 1‐hour intervals, and then compared these estimates to nocturnal measurements of CO2 exchange by eddy covariance. Soil surface respiration was the largest source of CO2 at all sites (48–71%), and foliar respiration made a large contribution to ecosystem respiration at all sites (25–43%). Woody tissue respiration contributed only 5–15% to ecosystem respiration. We estimated error for the scaled chamber predictions of ecosystem respiration by using the uncertainty associated with each respiration parameter and respiring biomass value. There was substantial uncertainty in estimates of foliar and soil respiration because of the spatial variability of specific respiration rates. In addition, more attention needs to be paid to estimating foliar respiration during the early part of the growing season, when new foliage is growing, and to determining seasonal trends of soil surface respiration. Nocturnal eddy covariance measurements were poorly correlated to scaled chamber estimates of ecosystem respiration (r2=0.06–0.27) and were consistently lower than scaled chamber predictions (by 27% on average for the six sites). The bias in eddy covariance estimates of ecosystem respiration will alter estimates of gross assimilation in the light and of net ecosystem exchange rates over extended periods.}, number={D24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Lavigne, MB and Ryan, MG and Anderson, DE and Baldocchi, DD and Crill, PM and Fitzjarrald, DR and Goulden, ML and Gower, ST and Massheder, JM and McCaughey, JH and et al.}, year={1997}, month={Dec}, pages={28977–28985} }
 @article{fassnacht_gower_mackenzie_nordheim_lillesand_1997, title={Estimating the leaf area index of North Central Wisconsin forests using the Landsat Thematic Mapper}, volume={61}, ISSN={["0034-4257"]}, DOI={10.1016/s0034-4257(97)00005-9}, abstractNote={Leaf area index (LAI) is an extremely important structural characteristic of vegetation because it is directly related to the exchange of energy, CO2 and mass from plant canopies at a variety of scales. Research investigating the relationship between forest LAI and satellite data for hardwood and mixed conifer-hardwood forests is lacking, however. The objective of this study was to explore the utility of Landsat-5 Thematic Mapper (TM) data for accurately estimating the LAI of conifer, hardwood, and mixed conifer-hardwood forests in north central Wisconsin. Individual bands and vegetation indices (VIs) calculated from satellite measures of exoatmospheric reflectance were related to the litterfall-estimated LAI of 24 stands. The results showed that individual bands or VIs containing at least one infrared (IR) band (either near- or mid-infrared) or a strong IR component divided data into at least two groups, with each group requiring a different regression line. The primary division was between conifer-dominated and hardwood-doin inated stands. Of the individual bands and VI.s considered, seven were strongly correlated to the LAI of conifer stands (r2=0.69–0.73). For the hardwoods, the best individual band or VI was Green/mid-IR#1 (r2=0.35), although an additional individual band and two VIs did much better using re subset of lower LAI stands (r2=0.60–0.75). For individual bands and VIs not requiring a conifer-hardwood distinction, the sixth Tasseled Cap component was most closely related to LAI (r2=0.60). Multiple-variable models (using LAI as the dependent variable) were found to offer substantial improvement over single-variable models, especially for hardwood stands. We recommend for further consideration a four-variable model for the conifers, and one four-variable and two eight-variable models for the hardwoods.}, number={2}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Fassnacht, KS and Gower, ST and MacKenzie, MD and Nordheim, EV and Lillesand, TM}, year={1997}, month={Aug}, pages={229–245} }
 @article{fassnacht_gower_1997, title={Interrelationships among the edaphic and stand characteristics, leaf area index, and aboveground net primary production of upland forest ecosystems in north central Wisconsin}, volume={27}, DOI={10.1139/x97-058}, abstractNote={The objectives of this study were to (1) examine the relationships between site factors and both leaf area index (LAI) and aboveground net primary production (ANPP) of conifer, mixed conifer-hardwood, and hardwood forests in north central Wisconsin and (2) determine the relationship between LAI and ANPP. LAI ranged from 1.2 ha·ha -1 for a jack pine (Pinus banksianaLamb.) forest to 8.4 ha·ha -1 for a sugar maple (Acer saccharumMarsh.) dominated forest. LAI was significantly correlated with potential available water and nutrient availability, with both potassium and nitrogen identified as possibly influential elements. ANPP ranged from 2.9 (jack pine) to 11.5 t·ha -1 ·year -1 (sugar maple). Variability in ANPP was explained primarily by changes in specific leaf area, which was highly correlated with percent hardwood LAI. ANPP was positively correlated with LAI (r 2 = 0.82, p < 0.001) for all stands, but the relationship was not as strong for conifer ( r 2 = 0.62, p = 0.007) and hardwood (r 2 = 0.47, p = 0.007) stands when analyzed separately. There was evidence that production efficiency (ANPP/LAI) differed between conifer and hardwood stands, but the study design did not allow us to rigorously test this question. Resume : Les objectifs de cette etude consiaient 1) a etudier les relations entre les facteurs stationnels et l'indice de surface foliaire (LAI) ainsi que la productivite primaire nette epigee (ANPP) des forets de coniferes, des forets metlangees de coniferes et de feuillus et des forets feuillues dans le Centre-Nord du Wisconsin et 2) a determiner s'il existe une relation entre LAI et ANPP. LAI variait de 1,2 ha·ha -1 pour une foret de pin gris (Pinus banksiana Lamb.) a 8,4 ha·ha -1 pour une foret dominee par l'erable a sucre (Acer saccharumMarsh.). LAI etait significativement correle avec l'humidite potentiellement disponible et la disponibilite des nutriments, l'azote et le potassium etant possiblement des elements importants. ANPP variait de 2,9 (pin gris) a 11,5 t·ha -1 ·an -1 (erable a sucre). La variabilite de ANPP s'expliquait surtout par les changements dans la surface foliaire specifique, laquelle etait fortement correlee avec le pourcentage de LAI feuillu. ANPP etait positivement correle (r 2 = 0,82, p < 0,001) avec LAI pour tous les peuplements, mais la relation n'etait pas aussi forte lorsque les peuplements resineux (r 2 = 0,62, p < 0,007) et feuillus (r 2 = 0,47, p < 0,007) etaient analyses separement. Il y avait des indices que l'efficacite de la production (ANPP/LAI) des peuplements resineux et feuillus differait, mais le dispositif experimental utilise dans cette etude ne permettait pas de verifier rigoureusement cette hypothese. (Traduit par la Redaction)}, number={7}, journal={Canadian Journal of Forest Research}, author={Fassnacht, K. S. and Gower, S. T.}, year={1997}, pages={1058–1067} }
 @article{chen_rich_gower_norman_plummer_1997, title={Leaf area index of boreal forests: Theory, techniques, and measurements}, volume={102}, ISSN={["2169-8996"]}, DOI={10.1029/97jd01107}, abstractNote={Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LAI estimates are required in studies of ecophysiology, atmosphere‐ecosystem interactions, and global change. The objective of this paper is to evaluate LAI values obtained by several research teams using different methods for a broad spectrum of boreal forest types in support of the international Boreal Ecosystem‐Atmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI‐2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LAI from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LAI of boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LAI falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LAI estimates available for boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LAI measurements.}, number={D24}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Chen, JM and Rich, PM and Gower, ST and Norman, JM and Plummer, S}, year={1997}, month={Dec}, pages={29429–29443} }
 @article{reich_grigal_aber_gower_1997, title={Nitrogen mineralization and productivity in 50 hardwood and conifer stands on diverse soils}, volume={78}, DOI={10.2307/2266011}, number={2}, journal={Ecology}, author={Reich, P. B. and Grigal, D. F. and Aber, J. D. and Gower, S. T.}, year={1997}, pages={335–347} }
 @inproceedings{magnuson_kratz_allen_armstrong_benson_bowser_bolgrien_carpenter_frost_gower_et al._1997, title={Regionalization of long-term ecological research (LTER) on north temperate lakes}, volume={26}, DOI={10.1080/03680770.1995.11900771}, abstractNote={(1997). Regionalization of long-term ecological research (LTER) on north temperate lakes. SIL Proceedings, 1922-2010: Vol. 26, No. 2, pp. 522-528.}, number={2}, booktitle={International association of theoretical and applied limnology -}, author={Magnuson, J. J. and Kratz, T. K. and Allen, T. F. and Armstrong, D. E. and Benson, B. J. and Bowser, C. J. and Bolgrien, D. W. and Carpenter, S. R. and Frost, T. M. and Gower, S. T. and et al.}, year={1997}, pages={522–528} }
 @article{steele_gower_vogel_norman_1997, title={Root mass, net primary production and turnover in aspen, jack pine and black spruce forests in Saskatchewan and Manitoba, Canada}, volume={17}, DOI={10.1093/treephys/17.8-9.577}, abstractNote={Root biomass, net primary production and turnover were studied in aspen, jack pine and black spruce forests in two contrasting climates. The climate of the Southern Study Area (SSA) near Prince Albert, Saskatchewan is warmer and drier in the summer and milder in the winter than the Northern Study Area (NSA) near Thompson, Manitoba, Canada. Ingrowth soil cores and minirhizotrons were used to quantify fine root net primary production (NPPFR). Average daily fine root growth (m m(-2) day(-1)) was positively correlated with soil temperature at 10-cm depth (r(2) = 0.83-0.93) for all three species, with black spruce showing the strongest temperature effect. At both study areas, fine root biomass (measured from soil cores) and fine root length (measured from minirhizotrons) were less for jack pine than for the other two species. Except for the aspen stands, estimates of NPPFR from minirhizotrons were significantly greater than estimates from ingrowth cores. The core method underestimated NPPFR because it does not account for simultaneous fine root growth and mortality. Minirhizotron NPPFR estimates ranged from 59 g m(-2) year(-1) for aspen stands at SSA to 235 g m(-2) year(-1) for black spruce at NSA. The ratio of NPPFR to total detritus production (aboveground litterfall + NPPFR) was greater for evergreen forests than for deciduous forests, suggesting that carbon allocation patterns differ between boreal evergreen and deciduous forests. In all stands, NPPFR consistently exceeded annual fine root turnover and the differences were larger for stands in the NSA than for stands in the SSA, whereas the difference between study areas was only significant for black spruce. The imbalance between NPPFR and fine root turnover is sufficient to explain the net accumulation of carbon in boreal forest soils.}, number={8-9}, journal={Tree Physiology}, author={Steele, S. J. and Gower, S. T. and Vogel, J. G. and Norman, J. M.}, year={1997}, pages={577–587} }
 @inproceedings{norman_kucharik_gower_1996, title={A comparison of five methods for measuring soil surface carbon dioxide fluxes}, booktitle={22nd Conference on Agricultural & Forest Meteorology with Symposium on Fire & Forest Meteorology/12th Conference on Biometeorology & Aerobiology}, author={Norman, J. M. and Kucharik, C. J. and Gower, S. T.}, year={1996}, pages={59–61} }
 @article{gower_pongracic_landsberg_1996, title={A global trend in belowground carbon allocation: Can we use the relationship at smaller scales?}, volume={77}, ISSN={["0012-9658"]}, DOI={10.2307/2265780}, abstractNote={We compared independent estimates of total root carbon allocation (TRCA) and fine root net primary production $(NPP_{fr})$ for temperate forests to total root carbon allocation (TRCA—RN) estimates derived from an empirical model developed by J. W. Raich and K. J. Nadelhoffer for world forests. Measured total root carbon allocation for temperate forests ranged from 233 to 1013 g $C\cdot m{—2}\cdot yr{—1}$ and was not correlated to TRCA calculated from the Raich and Nadelhoffer model for world forests. Fine root NPP was not correlated to TRCA—RN; however, a strong correlation was found between $NPP_{fr}$ and TRCA—RN for five control Pinus resinosa natural forests and plantations. The poor correlation between measured TRCA or $NPP_{fr}$ and the estimates may be due to interspecies differences in belowground carbon allocation, variation in foliage: root carbon allocation ratios due to water and nutrient availability, and violations in the carbon budget approach. Using the Raich and Nadelhoffer model to estimate total root carbon allocation and to construct stand carbon budgets for a stand is not an acceptable substitute for measuring soil carbon fluxes.}, number={6}, journal={ECOLOGY}, author={Gower, ST and Pongracic, S and Landsberg, JJ}, year={1996}, month={Sep}, pages={1750–1755} }
 @misc{gower_mcmurtrie_murty_1996, title={Aboveground net primary production decline with stand age: Potential causes}, volume={11}, ISSN={["0169-5347"]}, DOI={10.1016/0169-5347(96)10042-2}, abstractNote={Aboveground net primary production (ANPP) commonly reaches a maximum in young forest stands and decreases by 0-76% as stands mature. However, the mechanism(s) responsible for the decline are not well understood. Current hypotheses for declining ANPP with stand age include: (1) an altered balance between photosynthetic and respiring tissues, (2) decreasing soil nutrient availability, and (3) increasing stomatal limitation leading to reduced photosynthetic rates. Recent empirical and modeling studies reveal that mechanisms (2) and (3) are largely responsible for age-related decline in ANPP for forests in cold environments. Increasing respiratory costs appear to be relatively unimportant in explaining declining productivity in ageing stands.}, number={9}, journal={TRENDS IN ECOLOGY & EVOLUTION}, author={Gower, ST and McMurtrie, RE and Murty, D}, year={1996}, month={Sep}, pages={378–382} }
 @article{haynes_gower_1995, title={BELOWGROUND CARBON ALLOCATION IN UNFERTILIZED AND FERTILIZED RED PINE PLANTATIONS IN NORTHERN WISCONSIN}, volume={15}, ISSN={["0829-318X"]}, DOI={10.1093/treephys/15.5.317}, abstractNote={We estimated carbon allocation to belowground processes in unfertilized and fertilized red pine (Pinus resinosa Ait.) plantations in northern Wisconsin to determine how soil fertility affects belowground allocation patterns. We used soil CO(2) efflux and litterfall measurements to estimate total belowground carbon allocation (root production and root respiration) by the carbon balance method, established root-free trenched plots to examine treatment effects on microbial respiration, estimated fine root production by sequential coring, and developed allometric equations to estimate coarse root production. Fine root production ranged from 150 to 284 g m(-2) year(-1) and was significantly lower for fertilized plots than for unfertilized plots. Coarse root production ranged from 60 to 90 g m(-2) year(-1) and was significantly lower for fertilized plots than for unfertilized plots. Annual soil CO(2) fluxes ranged from 331 to 541 g C m(-2) year(-1) and were significantly lower for fertilized plots than for unfertilized plots. Annual foliage litterfall ranged from 110 to 187 g C m(-2) year(-1) and was significantly greater for fertilized plots than for unfertilized plots. Total belowground carbon allocation ranged from 188 to 395 g C m(-2) year(-1) and was significantly lower for fertilized than for unfertilized plots. Annual soil CO(2) flux was lower for trenched plots than for untrenched plots but did not differ between fertilized and unfertilized trenched plots. Collectively, these independent estimates suggest that fertilization decreased the relative allocation of carbon belowground.}, number={5}, journal={TREE PHYSIOLOGY}, author={HAYNES, BE and GOWER, ST}, year={1995}, month={May}, pages={317–325} }
 @article{kloeppel_gower_1995, title={CONSTRUCTION AND INSTALLATION OF ACRYLIC MINIRHIZOTRON TUBES IN FOREST ECOSYSTEMS}, volume={59}, ISSN={["0361-5995"]}, DOI={10.2136/sssaj1995.03615995005900010037x}, abstractNote={Abstract}, number={1}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={KLOEPPEL, BD and GOWER, ST}, year={1995}, pages={241–243} }
 @inproceedings{gower_kloeppel_reich_1995, title={Carbon, nitrogen, and water use by larches and co-occurring evergreen conifers}, volume={319}, booktitle={Ecology and management of larix forests: a look ahead: proceedings of an international symposium}, author={Gower, S. T. and Kloeppel, B. D. and Reich, P. B.}, year={1995}, pages={110–117} }
 @inproceedings{kloeppel_gower_reich_1995, title={Net photosynthesis of western larch and sympatric evergreen conifers along a precipitation gradient in western Montana}, volume={319}, booktitle={Ecology and management of larix forests: a look ahead: proceedings of an international symposium}, author={Kloeppel, B. D. and Gower, S. T. and Reich, P. B.}, year={1995}, pages={486–489} }
 @article{ryan_gower_hubbard_waring_gholz_cropper_running_1995, title={WOODY TISSUE MAINTENANCE RESPIRATION OF 4 CONIFERS IN CONTRASTING CLIMATES}, volume={101}, ISSN={["0029-8549"]}, DOI={10.1007/bf00317276}, abstractNote={We estimate maintenance respiration for boles of four temperate conifers (ponderosa pine, western hemlock, red pine, and slash pine) from CO 2  efflux measurements in autumn, when construction respiration is low or negligible. Maintenance respiration of stems was linearly related to sapwood volume for all species; at 10°C, respiration per unit sapwood volume ranged from 4.8 to 8.3 μmol CO 2  m -3  s -1 . For all sites combined, respiration increased exponentially with temperature (Q  10  =1.7, r  2 =0.78). We estimate that maintenance respiration of aboveground woody tissues of these conifers consumes 52-162 g C m -2  y -1 , or 5-13% of net daytime carbon assimilation annually. The fraction of annual net daytime carbon fixation used for stem maintenance respiration increased linearly with the average annual temperature of the site.}, number={2}, journal={OECOLOGIA}, author={RYAN, MG and GOWER, ST and HUBBARD, RM and WARING, RH and GHOLZ, HL and CROPPER, WP and RUNNING, SW}, year={1995}, month={Feb}, pages={133–140} }
 @article{fassnacht_gower_norman_mcmurtrie_1994, title={A COMPARISON OF OPTICAL AND DIRECT-METHODS FOR ESTIMATING FOLIAGE SURFACE-AREA INDEX IN FORESTS}, volume={71}, ISSN={["0168-1923"]}, DOI={10.1016/0168-1923(94)90107-4}, abstractNote={Measurement of foliage surface area index (foliage SAI) is prominent in studies of terrestrial ecosystems because it is an important determinant of water, carbon, and energy exchange at the stand, landscape, and global scales, yet is very time consuming and labor intensive to measure directly. The objectives of this study were to 1) compare the resolution and accuracy of the Ceptometer, LAI-2000, and DEMON which measure a vegetation area index (VAI; includes branches, stems, cones, etc. in addition to leaves) optically using light interception, 2) examine the utility of logarithmic versus linear averaging and a correction factor proposed by Gower and Norman (1991), and 3) determine if there is a 'universal' regression relating optical and direct estimates of SAI across the range of foliage areas for most North American forests (and if one exists, how it relates to individual site regressions). For our analysis, data collected in open canopy natural ponderosa pine (Pinus ponderosa Dougl. ex Laws) forests and closed canopy red pine (Pinus resinosa Ait.) plantations were combined with data from previous studies which used one or more of the instruments. We found all instruments generally underestimated SAI when compared with direct estimates. Logarithmic averages of light transmittance reduced this problem, especially for conifer forests with foliage clumped at the shoot and canopy levels. The DEMON, using logarithmically averaged data, provided the most accurate optical estimates of SAI. We did not find the clumping correction factor suggested by Gower and Norman (1991) to be useful and suggest an alternative correction technique that is based on hemisurface area index (HSAI) and includes a shoot shape factor along with a clumping factor. Across a broad range in foliage SAI, all instruments provided optical estimates of SAI that were strongly correlated to direct estimates but the optical estimates were biased. The LAI-2000 (R2 = 0.93) and the DEMON logarithmic (R2 = 0.93) had the best fits. Because of the small size of the data sets evaluated, we strongly recommend the collection of larger data sets across a wider range of foliage SAIs to better test the strength of 'universal' regressions relating optical estimates of SAI to direct estimates.}, number={1-2}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={FASSNACHT, KS and GOWER, ST and NORMAN, JM and MCMURTRIE, RE}, year={1994}, month={Oct}, pages={183–207} }
 @article{gower_reich_son_1993, title={CANOPY DYNAMICS AND ABOVEGROUND PRODUCTION OF 5 TREE SPECIES WITH DIFFERENT LEAF LONGEVITIES}, volume={12}, ISSN={["0829-318X"]}, DOI={10.1093/treephys/12.4.327}, abstractNote={Canopy dynamics and aboveground net primary production (ANPP) were studied in replicated monospecific and dual-species plantations comprised of species with different leaf longevities. In the monospecific plantations, leaf longevity averaged 5, 6, 36, 46 and 66 months for Quercus rubra L., Larix decidua Miller, Pinus strobus L., Pinus resinosa Ait. and Picea abies (L.) Karst., respectively. Specific leaf area, maximum net photosynthesis per unit mass (A/mass), leaf N per unit mass (N(leaf)/mass) and maximum net photosynthesis on a leaf N basis (A/N(leaf)) were inversely correlated to leaf longevity (r(2) = 0.92-0.97, 0.91, 0.88 and 0.80, respectively). Maximum net photosynthesis per unit area (A/area) was not correlated to leaf longevity, whereas leaf N per unit area (N(leaf)/area) was positively correlated to leaf longevity (r(2) = 0.95). For a similar-diameter conifer, species with long-lived foliage supported a greater foliage mass than species with short-lived foliage; however, Quercus rubra did not follow this pattern. At the stand level, total foliage mass ranged from 3.3 to 30.5 Mg ha(-1) and was positively correlated (r(2) = 0.97) to leaf longevity. Leaf area index (LAI) was also positively correlated (r(2) = 0.82) to leaf longevity. Production efficiency (ANPP/LAI) was inversely related to leaf longevity and positively related to A/mass. Aboveground biomass and net primary production differed significantly (P < 0.05) among the five species but were not correlated to leaf longevity, total foliage mass or leaf area. In monospecific plantations, stem NPP for Larix decidua was 17% greater than for Pinus strobus and 14% less than for Picea abies, but in mixed-species plantations stem NPP for Larix decidua was 62 and 85% greater than for Pinus strobus and Picea abies, respectively. Similar aboveground net primary production rates can be attained by tree species with different leaf longevities because of trade-offs resulting from different structural and physiological leaf and canopy characteristics that are correlated to each other and to leaf longevity.}, number={4}, journal={TREE PHYSIOLOGY}, author={GOWER, ST and REICH, PB and SON, Y}, year={1993}, month={Jun}, pages={327–345} }
 @article{gower_haynes_fassnacht_running_hunt_1993, title={INFLUENCE OF FERTILIZATION ON THE ALLOMETRIC RELATIONS FOR 2 PINES IN CONTRASTING ENVIRONMENTS}, volume={23}, ISSN={["1208-6037"]}, DOI={10.1139/x93-212}, abstractNote={ The objective of this study was to examine the effect of fertilization on the allometric relations for red pine (Pinusresinosa Ait.) and ponderosa pine (Pinusponderosa Dougl. ex Laws.) growing in contrasting climates. After 2 years of treatment, fertilization did not significantly affect the allometric relations between stem or branch mass and stem diameter for either species. For a similar-diameter tree, current foliage mass and area and new twig mass were significantly greater for fertilized than for control red pine and ponderosa pine. The significant increase in new foliage mass and area occurred in the upper and middle canopy for red pine and middle and lower canopy for ponderosa pine. For a similar-diameter tree, projected (one-sided) leaf area and total foliage mass were significantly greater for fertilized than for control red pine. However, leaf area and total foliage mass did not differ between similar-diameter fertilized and control ponderosa pine because fertilization decreased leaf longevity. The ratios of leaf area/sapwood cross-sectional area measured at breast height (1.37 m) were 0.14 and 0.11 for control plus fertilized red pine and ponderosa pine, respectively, and were greater (but not significantly) for fertilized than for control trees, while the ratios of leaf area/sapwood cross-sectional area measured at the base of live crown were significantly greater for fertilized than for control red pine and ponderosa pine. }, number={8}, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={GOWER, ST and HAYNES, BE and FASSNACHT, KS and RUNNING, SW and HUNT, ER}, year={1993}, month={Aug}, pages={1704–1711} }
 @article{gower_vogt_grier_1992, title={CARBON DYNAMICS OF ROCKY-MOUNTAIN DOUGLAS-FIR - INFLUENCE OF WATER AND NUTRIENT AVAILABILITY}, volume={62}, ISSN={["0012-9615"]}, DOI={10.2307/2937170}, abstractNote={Changes in biomass distribution, canopy dynamics, and above— and belowground net primary production were examined in a Rocky Mountain Douglas—fir (Pseudotsuga menziesii var. glauca forest in New Mexico. Nutrient and water availability were experimentally altered by: fertilization (F), irrigation (I), carbon in the form of wood chips (WC), carbon + irrigation (WC/I), and control (C). Prior to treatment, aboveground tree biomass ranged from 238 to 369 000 kg/ha, projected leaf area index (LAI) ranged from 5.4 to 8.7 m2/m2 and aboveground net primary production (ANPP) ranged from 9200 to 11 900 kg · ha—1 · yr—1. Aboveground NPP was correlated positively (R2 = 0.85) with LAI before the treatments. Canopy dynamics were strongly influenced by water and nutrient availability. For trees of similar diameter, irrigated and fertilized trees supported a significantly greater biomass of new twig and new foliage than control trees. During the 2—yr study leaf area index (LAI) increased by 5, 12, 18, and 24% in the C, I, WC/I, and F plots, respectively, and decreased by 3% in the WC plots. Stand level biomass distribution and production patterns were also affected by the availability of nutrients and water. Two years after the treatments were initiated, new foliage masses were 2400 (F), 2300 (WC/I), 2000 (I), 1900 (C), and 1800 (WC) kg/ha. In 1986, aboveground NPP was 33% greater in the F than WC treatment. Irrigation also increased ANPP. Fine root net primary production ranged from 1540 to 4200 kg · ha—1 · yr—1 and was significantly greater (P < .1) in the control than in the four treatments. BNPP comprised 46 (C), 32 (WC), 31 (I), 23 (WC/I), and 23 (F) % of total NPP. Total NPP was correlated positively with LAI (R2 = 0.66) and ranged from 15 360 kg · ha—1 · yr—1 in the WC treatment to 21 140 kg · ha—1 · yr—1 in the F treatment. Many of the physiological relations between water or nutrient availability and production and carbon allocation reported in this study are consistent with results from studies on lowland Douglas—fir and other conifer forests in the Pacific Northwest. Collectively, these studies provide a mechanistic understanding of how water and nutrient availability govern production and carbon allocation of conifer forests in the western United States.}, number={1}, journal={ECOLOGICAL MONOGRAPHS}, author={GOWER, ST and VOGT, KA and GRIER, CC}, year={1992}, month={Mar}, pages={43–65} }
 @article{gower_son_1992, title={DIFFERENCES IN SOIL AND LEAF LITTERFALL NITROGEN DYNAMICS FOR 5 FOREST PLANTATIONS}, volume={56}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj1992.03615995005600060051x}, abstractNote={Abstract}, number={6}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={GOWER, ST and SON, Y}, year={1992}, pages={1959–1966} }
 @article{son_gower_1992, title={NITROGEN AND PHOSPHORUS DISTRIBUTION FOR 5 PLANTATION SPECIES IN SOUTHWESTERN WISCONSIN}, volume={53}, ISSN={["1872-7042"]}, DOI={10.1016/0378-1127(92)90042-8}, abstractNote={Nutrient distribution was determined in the soil and vegetation for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller), white pine (Pinus strobus L.), red pine (Pinus resinosa Ait.) and Norway spruce (Picea abies (L) Karst.) plantations on a similar soil in southwestern Wisconsin. The concentration and content of several soil nutrients differed among the five species, but no consistent patterns were observed between deciduous and evergreen species. Current foliage nitrogen (N) and phosphorus (P) concentration for European larch and N concentration for red pine decreased down the canopy but did not differ significantly among canopy positions for the other tree species. In general, total N and P content were greatest in the upper 30 cm of soil followed by aboveground vegetation and forest floor. Total N and P content in aboveground vegetation were positively correlated to leaf longevity (r2 = 0.83, P < 0.05 for N; r2 = 0.79, P < 0.05 for P); aboveground N and P content (kg ha−1) were 258 and 26 for red oak, 261 and 41 for European larch, 500 and 57 for white pine, 431 and 49 for red pine, and 687 and 97 for Norway spruce. We estimated that whole tree harvesting (stem + branch + foliage) would remove 120–380% more N and 100–610% more P than stem-only harvests in these plantations.}, number={1-4}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={SON, Y and GOWER, ST}, year={1992}, month={Oct}, pages={175–193} }
 @article{matson_gower_volkmann_billow_grier_1992, title={SOIL-NITROGEN CYCLING AND NITROUS-OXIDE FLUX IN A ROCKY-MOUNTAIN DOUGLAS-FIR FOREST - EFFECTS OF FERTILIZATION, IRRIGATION AND CARBON ADDITION}, volume={18}, ISSN={["0168-2563"]}, DOI={10.1007/bf00002705}, number={2}, journal={BIOGEOCHEMISTRY}, author={MATSON, PA and GOWER, ST and VOLKMANN, C and BILLOW, C and GRIER, CC}, year={1992}, pages={101–117} }
 @article{son_gower_1991, title={ABOVEGROUND NITROGEN AND PHOSPHORUS USE BY 5 PLANTATION-GROWN TREES WITH DIFFERENT LEAF LONGEVITIES}, volume={14}, ISSN={["0168-2563"]}, DOI={10.1007/bf00000806}, number={3}, journal={BIOGEOCHEMISTRY}, author={SON, Y and GOWER, ST}, year={1991}, pages={167–191} }
 @article{chapman_gower_1991, title={ABOVEGROUND PRODUCTION AND CANOPY DYNAMICS IN SUGAR MAPLE AND RED OAK TREES IN SOUTHWESTERN WISCONSIN}, volume={21}, ISSN={["1208-6037"]}, DOI={10.1139/x91-214}, abstractNote={ Aboveground net primary production, canopy allometry, growth efficiency, and sapwood volume were compared for early- to mid-successional red oak (Quercusrubra L.) and late-successional sugar maple (Acersaccharum Marsh.) co-occurring in young and mature natural stands in southwestern Wisconsin. For similar-diameter trees, shade-tolerant sugar maple supported a significantly greater (p < 0.05) stem, branch, and foliage biomass and leaf area than mid-tolerant red oak. Red oak and sugar maple had similar stem net primary production rates over a 5-year period (1984–1988), but sugar maple had a significantly greater total aboveground net primary production than similar-diameter red oak. However, red oak had a significantly greater (p < 0.0001) growth efficiency (stem net primary production per unit of leaf area) than sugar maple. The significantly greater sapwood volume, but equal stem volume, of sugar maple versus red oak suggests that annual stem maintenance respiration costs may be greater for sugar maple than for red oak. Possible causes for differences in stem net primary production and growth efficiency between early- and late-successional tree species are discussed. }, number={10}, journal={CANADIAN JOURNAL OF FOREST RESEARCH}, author={CHAPMAN, JW and GOWER, ST}, year={1991}, month={Oct}, pages={1533–1543} }
 @article{running_gower_1991, title={FOREST-BGC, A GENERAL-MODEL OF FOREST ECOSYSTEM PROCESSES FOR REGIONAL APPLICATIONS .2. DYNAMIC CARBON ALLOCATION AND NITROGEN BUDGETS}, volume={9}, ISSN={["1758-4469"]}, DOI={10.1093/treephys/9.1-2.147}, abstractNote={A new version of the ecosystem process model FOREST-BGC is presented that uses stand water and nitrogen limitations to alter the leaf/root/stem carbon allocation fraction dynamically at each annual iteration. Water deficit is defined by integrating a daily soil water deficit fraction annually. Current nitrogen limitation is defined relative to a hypothetical optimum foliar N pool, computed as maximum leaf area index multiplied by maximum leaf nitrogen concentration. Decreasing availability of water or nitrogen, or both, reduces the leaf/root carbon partitioning ratio. Leaf and root N concentrations, and maximum leaf photosynthetic capacity are also redefined annually as functions of nitrogen availability. Test simulations for hypothetical coniferous forests were performed for Madison, WI and Missoula, MT, and showed simulated leaf area index ranging from 4.5 for a control stand at Missoula, to 11 for a fertilized stand at Madison, with Year 50 stem carbon biomasses of 31 and 128 Mg ha(-1), respectively. Total nitrogen incorporated into new tissue ranged from 34 kg ha(-1) year(-1) for the unfertilized Missoula stand, to 109 kg ha(-1) year(-1) for the fertilized Madison stand. The model successfully showed dynamic annual carbon partitioning controlled by water and nitrogen limitations.}, number={1-2}, journal={TREE PHYSIOLOGY}, author={RUNNING, SW and GOWER, ST}, year={1991}, pages={147–160} }
 @article{gower_norman_1991, title={RAPID ESTIMATION OF LEAF-AREA INDEX IN CONIFER AND BROAD-LEAF PLANTATIONS}, volume={72}, ISSN={["0012-9658"]}, DOI={10.2307/1940988}, abstractNote={EcologyVolume 72, Issue 5 p. 1896-1900 Article Rapid Estimation of Leaf Area Index in Conifer and Broad-Leaf Plantations Stith T. Gower, Stith T. GowerSearch for more papers by this authorJohn M. Norman, John M. NormanSearch for more papers by this author Stith T. Gower, Stith T. GowerSearch for more papers by this authorJohn M. Norman, John M. NormanSearch for more papers by this author First published: 01 October 1991 https://doi.org/10.2307/1940988Citations: 264AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume72, Issue5October 1991Pages 1896-1900 RelatedInformation}, number={5}, journal={ECOLOGY}, author={GOWER, ST and NORMAN, JM}, year={1991}, month={Oct}, pages={1896–1900} }
 @article{gower_chapman_volin_hagen_1991, title={Stem biomass growth of four plantation-grown conifer species in southwestern Wisconsin}, volume={8}, number={1}, journal={Northern Journal of Applied Forestry}, author={Gower, S. T. and Chapman, J. W. and Volin, J. C. and Hagen, A. E.}, year={1991}, pages={26–28} }
 @article{bolstad_gower_1990, title={ESTIMATION OF LEAF-AREA INDEX IN 14 SOUTHERN WISCONSIN FOREST STANDS USING A PORTABLE RADIOMETER}, volume={7}, ISSN={["0829-318X"]}, DOI={10.1093/treephys/7.1-2-3-4.115}, abstractNote={Projected leaf area index (LAI) and Beer-Lambert Law extinction coefficients (K) were estimated for 28-year-old Picea abies (L.) Karst., Larix decidua Mill., Pinus resinosa Ait., and Pinus strobus L. plantations using vertical profile data obtained with a portable integrating radiometer (sunfleck ceptometer). Predicted LAI values were compared with direct measures of LAI. Based on dimensional analysis, LAI ranged from 5.0 for Larix decidua to 10.5 for Picea abies. Significant inverse relationships between cumulative LAI and canopy transmitted radiation were observed for the four species (R(2) = 0.92-0.97). Beer-Lambert extinction coefficients ranged from 0.39 for Picea abies to 0.84 for Pinus strobus. Stand-level predictions of LAI based on the Beer-Lambert Law were compared with measured LAI values for eight conifer and six broadleaf stands. Using local K estimates resulted in predicted LAI values with an average 6% error. Using published K values resulted in an average error of 20%. High LAI and concomitantly low light levels below the canopy of Picea abies stands resulted in large overestimation errors in predicted LAI, rendering the sunfleck ceptometer inappropriate for forests with large LAIs.}, number={1-4}, journal={TREE PHYSIOLOGY}, author={BOLSTAD, PV and GOWER, ST}, year={1990}, month={Dec}, pages={115–124} }
 @article{gower_richards_1990, title={Larches - deciduous conifers in an evergreen world}, volume={40}, DOI={10.2307/1311484}, abstractNote={Journal Article Larches: Deciduous Conifers in an Evergreen World Get access Stith T. Gower, Stith T. Gower Search for other works by this author on: Oxford Academic Google Scholar James H. Richards James H. Richards Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 40, Issue 11, December 1990, Pages 818–826, https://doi.org/10.2307/1311484 Published: 01 December 1990}, number={11}, journal={BioScience}, author={Gower, S. T. and Richards, J. H.}, year={1990}, pages={818–826} }
 @article{reich_ellsworth_kloeppel_fownes_gower_1990, title={VERTICAL VARIATION IN CANOPY STRUCTURE AND CO2 EXCHANGE OF OAK-MAPLE FORESTS - INFLUENCE OF OZONE, NITROGEN, AND OTHER FACTORS ON SIMULATED CANOPY CARBON GAIN}, volume={7}, ISSN={["0829-318X"]}, DOI={10.1093/treephys/7.1-2-3-4.329}, abstractNote={Stand-level and physiological measurements were made for oak and maple species common in Wisconsin forests. Scaling relationships were identified to allow the development of a model for estimating net carbon exchange at the levels of a leaf, canopy stratum, and whole canopy. Functional relationships were determined between tissue gas exchange rates and perceived controlling variables. Vertical variation in leaf properties and in the distribution of foliage by weight, area, and species were characterized for several closed canopy forests. Forest canopies were divided into four horizontal strata to develop predictive models for canopy gas exchange. Leaf and canopy layer carbon dioxide exchange rates were predicted using leaf nitrogen concentration, leaf mass per area, ozone exposure, predawn leaf water potential, photosynthetically active radiation, and vapor pressure deficit as driving variables. Direct measurements of leaf gas exchange were used to validate the components (subroutines) of the model. Net carbon dioxide exchange was simulated for canopy layers at 5-min intervals over a diurnal time course. Simulations of canopy CO(2) exchange were made for a 30-m tall, mixed oak-maple forest under hypothetical ambient and greater-than-ambient ozone pollution regimes. Daily canopy net CO(2) exchange was predicted for seven forest stands and compared with estimates of aboveground net primary production, N availability, leaf area index, and canopy N.}, number={1-4}, journal={TREE PHYSIOLOGY}, author={REICH, PB and ELLSWORTH, DS and KLOEPPEL, BD and FOWNES, JH and GOWER, ST}, year={1990}, month={Dec}, pages={329–345} }
 @article{gower_grier_1989, title={ABOVE-GROUND ORGANIC-MATTER AND PRODUCTION OF A MONTANE FOREST ON THE EASTERN SLOPES OF THE WASHINGTON CASCADE RANGE}, volume={19}, ISSN={["0045-5067"]}, DOI={10.1139/x89-079}, abstractNote={ Aboveground biomass and production were determined for a 70-year-old mixed conifer forest of western larch (Larixoccidentalis Nutt.), lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on the eastern slopes of the Cascade Range in Washington state. Live aboveground biomass, projected leaf area, and aboveground net primary production for the mixed conifer forest were 194 Mg•ha−1, 4.2 m−2•m−2, and 6.1 Mg•ha−1•year−1, respectively. Based on the few studies of montane forests on the eastern slope of the Cascades, aboveground biomass, leaf area index, and aboveground net primary production of these forests are more similar to those of montane coniferous forests in the Rocky Mountains than to those of similar forests located on the western slopes of the Cascades. }, number={4}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={GOWER, ST and GRIER, CC}, year={1989}, month={Apr}, pages={515–518} }
 @article{gower_grier_vogt_1989, title={Above-ground production and N and P use by Larix-occidentalis and Pinus-contorta in the Washington Cascades, USA}, volume={5}, DOI={10.1093/treephys/5.1.1}, abstractNote={Aboveground net primary production (ANPP) and N and P use patterns were determined for western larch (Larix occidentalis Nutt.), a deciduous conifer, and lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), an evergreen conifer, in the Cascade Mountains of Washington, USA. Western larch and lodgepole pine retranslocated 87 and 66% of foliage N and 66 and 78% of foliage P, respectively. At the stand level, N use efficiency of western larch was greater than that of lodgepole pine, whereas P use efficiency of lodgepole pine was greater than that of western larch. Western larch and lodgepole pine were comparable in ANPP and production efficiency (ANPP/foliage mass) if needle longevity is considered. The similarity in ANPP of the evergreen lodgepole pine and the deciduous western larch may be related in part to the lower initial construction cost of the foliage, and the efficient use of nitrogen by western larch.}, number={1}, journal={Tree Physiology}, author={Gower, S. T. and Grier, C. C. and Vogt, K. A.}, year={1989}, pages={1–11} }
 @article{gower_vitousek_1989, title={EFFECTS OF NUTRIENT AMENDMENTS ON FINE ROOT BIOMASS IN A PRIMARY SUCCESSIONAL FOREST IN HAWAII}, volume={81}, ISSN={["1432-1939"]}, DOI={10.1007/bf00378970}, abstractNote={We determined the effect of fertilization treatments (control (C), complete nutrient amendment without nitrogen (PT), nitrogen only (N) and a complete nutrient amendment (NPT)) on fine root biomass in a tropical montane forest in Hawai'i. Fertilization significantly decreased root biomass; live fine root mass (<2 mm diameter) for the C, PT, N and NPT treatments were 335, 145, 110 and 105 g·m -2 , respectively. Nutrient availability appears to control fine root mass in this primary successional forest.}, number={4}, journal={OECOLOGIA}, author={GOWER, ST and VITOUSEK, PM}, year={1989}, pages={566–568} }
 @article{gower_grier_vogt_vogt_1987, title={ALLOMETRIC RELATIONS OF DECIDUOUS (LARIX-OCCIDENTALIS) AND EVERGREEN CONIFERS (PINUS-CONTORTA AND PSEUDOTSUGA-MENZIESII) OF THE CASCADE MOUNTAINS IN CENTRAL WASHINGTON}, volume={17}, ISSN={["0045-5067"]}, DOI={10.1139/x87-103}, abstractNote={ Logarithmic equations for estimating component biomass and projected leaf area from stem diameter and (or) sapwood cross-sectional area were computed for western larch (Larixoccidentalis Nutt.), lodgepole pine (Pinuscontorta Dougl.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) in a mixed conifer stand in the Cascades of central Washington. Regression equations for estimating foliage biomass reported in this study did not compare favorably with foliage biomass allometric relations from other studies. For a given diameter, western larch supported a greater current foliage mass than lodgepole pine or Douglas-fir (P < 0.001); however, the total foliage mass of lodgepole pine was significantly greater (P < 0.001) than western larch. Despite lodgepole pine supporting a total foliage mass approximately twofold greater than western larch, allometric relations between foliage area and stem diameter were not different (P > 0.05) between the deciduous and evergreen conifer. Western larch supports a needle morphology that provides a greater photosynthetic surface area per unit of carbon invested than evergreen conifers in this environment. }, number={7}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={GOWER, ST and GRIER, CC and VOGT, DJ and VOGT, KA}, year={1987}, month={Jul}, pages={630–634} }
 @article{gower_1987, title={RELATIONS BETWEEN MINERAL NUTRIENT AVAILABILITY AND FINE ROOT BIOMASS IN 2 COSTA RICAN TROPICAL WET FORESTS - A HYPOTHESIS}, volume={19}, ISSN={["1744-7429"]}, DOI={10.2307/2388741}, abstractNote={Fine root biomass was estimated for two Costa Rican broad-leaf evergreen forests with apparent differences in soil nutrient status. Live fine root biomass ( 200 mm of rainfall. Mean annual daily temperature is 20?C and diurnal temperature variation generally exceeds seasonal variation. Site selection was based on soil chemical analyses conducted on the major soil series (River and Arboleda) at La Selva, Costa Rica (Bourgeois et al. 1972). Soils of the selected stands are derived from different parent material. The River soil series is located on a terrace near the confluence of the Rio Puerto Viejo and the Sarapique and is largely alluvium of volcanic origin. The Arboleda soil series is found on an upland position and believed to have derived from basalt (Bourgeois et al. 1972). Classification of these soils according to the U.S. 7th Approximation was hampered by the lack of data on weatherable mineral content. Tentative classification for the River and Arboleda soil series are Fluvaquentic Hapludoll and Oxic Dystrandept, respectively (S. W. Buol, pers. comm.). Dominant canopy vegetation of the River site includes Castilla elastica Cerv., Cedralla mexicana Roem., Cordia allidora (Ruiz & Par.) Chan. ex aken, Cecropia obtusifolia Bert., Pterocarpus officinalis L., Spondias mombin L., and BIOTROPICA 19(2): 171-175 1987 171 This content downloaded from 207.46.13.115 on Sat, 08 Oct 2016 05:34:31 UTC All use subject to http://about.jstor.org/terms TABLE 1. Fine root biomass distribution of two Costa Rican lowland tropicalforest x ? (SE). Root diameter class (mm) Soil depth Live Site (N) (cm) 2-5 Total River 6 0-5 10(5) 11 (6) 23 (17) 127 6 5-10 6 (1) 10 (2) 35 (5) 77 6 10-20 4 (1) 7 (3) 5 (5) 60 6 20-30 1 (0) 6 (3) 1 (1) 81 3 30-40 2 (1) I (1) 0 (0) 14 3 40-50 <1 (0) 3 (2) 0 (0) 10 Total 23 38 64 369 (69) Arboleda 6 0-5 23 (7) 18 (8) 18 (12) 194 6 5-10 12 (1) 20 (8) 15 (6) 156 6 10-20 11 (8) 11 (8) 11 (7) 144 6 20-30 5 (1) 11 (8) 10 (7) 101 3 30-40 3 (2) 0 (0) 19 (19) 49 3 40-50 < 1 (0) 0 (0) 0 (0) 18 Total 54 60 73 662 (105) Terminalia lucida Hoffm. Because this site was a cacao plantation at one time, Theobroma cacao L. is found sporadically in the understory. The Arboleda canopy species include Pentacletbra macroloba Kuntze, Socratea durissma (Derst.) Wendl., Protium copal Engl. and Iriartea gigantea Wendl. (Bourgeois et al. 1972). Roots were sampled during March 3-5, 1983, with a 7-cm-diameter root corer. Sample locations were randomly selected along a transect perpendicular to the slope. Six cores to a 50 cm depth were sampled at each site. Sampling intensity was limited by the amount of freezer space available at the La Selva Research Station. Root cores were separated into 0-5, 5-10, 10-20, 20-30, 30-40, and 40-50 cm depth increments in the field and placed in plastic bags. Samples were frozen upon returning from the field and remained frozen during transportation to the U.S. Root core samples were stored at 10OC to minimize mass loss due to decomposition and respiration. Prior to sorting, root samples were thawed and washed in a nylon mesh sieve (0.5 mm opening) under distilled water. Roots were hand sorted under 10 x magnification from the remaining organic and mineral particles. Roots were separated according to physiological status (live versus dead) and root diameter classes (< 1, 1-2, 2-5 mm) and dried at 70?C to a constant mass. Root tissue was not dry-ashed because further chemical analyses were to be conducted on the remaining tissue. Live roots were distinguished by color and texture criterion. Preliminary work was conducted to substantiate that the root color and texture characteristics chosen to distinguish live and dead roots were correct. Positive identification of the physiological status was determined by 172 Gower preparing cross-sections of the selected roots using a freezing microtome and staining for starch granules with a potassium iodide-iodine solution. Only live roots have starch granules. Six 7-cm-diameter soil cores to a 50 cm depth were collected adjacent to root sampling locations and separated into 10 cm increments. Samples were subsampled. One mineral soil sample was oven-dried to a constant mass at 105?C and weighed to determine moisture content and bulk density. The remaining sample was dried at 70?C to a constant mass and saved for chemical analysis. Soil pH was determined in a 1:1 mixture following Mehlich (1976). Soil nitrogen was determined using a micro Kjeldahl procedure (Nicholson 1984) and analyzed colorimetrically on a Technicon AutoAnalyzer II. Soil to be analyzed for phosphorus and calcium was digested using Mehlich III procedure (Mehlich (1984), phosphorus was determined colorimetrically using a Brinkman PC600 colorimeter, and calcium was determined by atomic absorption using standard procedures. Mineral soil nutrient content was calculated by multiplying mineral nutrient concentration by bulk density and summing by soil depth. Statistical analyses of fine root biomass and soil chemical characteristics were conducted by using the Student's t-test, treating mean values as independent samples with equal variance (Steel & Torrie 1980).}, number={2}, journal={BIOTROPICA}, author={GOWER, ST}, year={1987}, month={Jun}, pages={171–175} }
 @article{vogt_grier_gower_sprugel_vogt_1986, title={OVERESTIMATION OF NET ROOT PRODUCTION - A REAL OR IMAGINARY PROBLEM}, volume={67}, ISSN={["0012-9658"]}, DOI={10.2307/1938601}, abstractNote={EcologyVolume 67, Issue 2 p. 577-579 Article Overestimation of Net Root Production: A Real or Imaginary Problem? Kristiina A. Vogt, Kristiina A. VogtSearch for more papers by this authorCharles C. Grier, Charles C. GrierSearch for more papers by this authorStith T. Gower, Stith T. GowerSearch for more papers by this authorDouglas G. Sprugel, Douglas G. SprugelSearch for more papers by this authorDaniel J. Vogt, Daniel J. VogtSearch for more papers by this author Kristiina A. Vogt, Kristiina A. VogtSearch for more papers by this authorCharles C. Grier, Charles C. GrierSearch for more papers by this authorStith T. Gower, Stith T. GowerSearch for more papers by this authorDouglas G. Sprugel, Douglas G. SprugelSearch for more papers by this authorDaniel J. Vogt, Daniel J. VogtSearch for more papers by this author First published: 01 April 1986 https://doi.org/10.2307/1938601Citations: 71AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume67, Issue2April 1986Pages 577-579 RelatedInformation}, number={2}, journal={ECOLOGY}, author={VOGT, KA and GRIER, CC and GOWER, ST and SPRUGEL, DG and VOGT, DJ}, year={1986}, month={Apr}, pages={577–579} }
 @article{gower_lea_frederick_clark_phillips_1985, title={ABOVE-GROUND ENERGY-PRODUCTION AND DISTRIBUTION OF SOUTHEASTERN HARDWOOD SWAMP FORESTS}, volume={7}, ISSN={["0144-4565"]}, DOI={10.1016/0144-4565(85)90007-1}, abstractNote={Energy production and distribution were examined in fully stocked, even-aged 10-, 20-, 40- and 60-year-old southeastern swamp forests. Maximum intraspecies energy value differences were small within a given tissue. Mean energy values (kJ g−1 dry weight) ranged as follows: foliage (18·76-21·17) >stem wood (19·04–20·34)>branch (19·11–19·85)>stem bark (16·72-20·33). Total live aboveground biomass and energy content in these swamp forests increased with stand age, as follows: 41·4, 108·8, 208·9 and 297·5 Mg ha−1 and 81·7, 209·0, 416·4 and 593·6 MJ m−2, respectively. Depending upon stand age, whole-tree harvest energy yields exceeded energy yields derived in a conventional harvest by 21–96%.}, number={3}, journal={BIOMASS}, author={GOWER, ST and LEA, R and FREDERICK, DJ and CLARK, A and PHILLIPS, DR}, year={1985}, pages={185–197} }
 @article{gower_frederick_clark_1984, title={DISTRIBUTION OF ENERGY IN DIFFERENT-AGED SOUTHEASTERN BOTTOMLAND FORESTS}, volume={9}, ISSN={["0378-1127"]}, DOI={10.1016/0378-1127(84)90078-1}, abstractNote={Abstract The distribution of biomass and energy content was determined for even-aged, fully stocked , 10-, 20-, 40- and 60-year-old Atlantic and Gulf Coastal Plain river bottom (red and black), wet flat, and swamp (muck and peat) forest ecosystems. Small differences in interspecies caloric values (kilogram calories per kilogram dry weight) were observed. These ranged from 4503–5018 kcal/kg for foliage, 4456–4792 for branches, 4456–4868 for stem wood, and 4242–4951 for stem bark. Mean caloric values decreased in the order of foliage > stem wood > branch > stem bark. Maximum caloric value differences among the three bottomland hardwood forest types for Acerrubrum were 2.5 (foliage), 2.3. (branch), 1.8 (stem bark), and 0.9 (stem wood), and for Liquidambar styraflua were 4.3 (branch), 3.1 (foliage), 2.3 (stem bark), and 0.8 (stem wood) percent, respectively. Sapling trees (⩾ 2.5 Conventional harvesting regimes (all stems ⩾ 12.7 cm dbh to a 10-cm dob top) were estimated to remove approximately 72 (swamp), 69 (wet flat), and 64 (river bottom) percent of the energy accumulated in 60-year-old forests. Whole-tree harvest (all material of trees ⩾ 2.5 cm dbh) removed an additional 396.2, 402.8 and 382.9 × 106 kcal/ha in 60-year-old swamp, wet flat and river bottom forests, respectively.}, number={2}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={GOWER, ST and FREDERICK, DJ and CLARK, A}, year={1984}, pages={127–146} }
 @book{biomass, nutrient and energy content of southeastern wetland hardwood forests_1983, number={2}, journal={Biomass, nutrient and energy content of southeastern wetland hardwood forests}, publisher={Raleigh: School of Forest Resources, North Carolina State University}, year={1983}, pages={28} }