@article{hackman_cook_strahm_carter_woodley_garcia_albaugh_rubilar_campoe_2024, title={<i>Pinus</i><i> taeda</i> carryover phosphorus availability on the lower Atlantic Coastal Plain}, volume={555}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2024.121701}, abstractNote={Phosphorus (P) fertilizer that remains in the soil after harvest and into the subsequent rotation is referred to as carryover P. Carryover P is not well understood in loblolly pine (P. taeda) silviculture, especially on highly P responsive sites, where this effect could potentially have the greatest benefit to land managers. Our study aims to determine the duration of the P carryover effect and the magnitude of response to soil P as it relates to previously applied P fertilizer rates from the previous rotation. To address this knowledge gap, we studied two highly weathered sites on the lower Atlantic coastal plain: a somewhat poorly drained Spodosol and a poorly drained Alfisol over three years from pre- to post-harvest. Two years post planting, carryover fertilizer treatments resulted in a 13% increase in height for the 121 kg P ha-1, a 15% for the 81 kg P ha-1, and a 17% increase for the fertilized 40 + 45 kg P ha-1 treatments compared to the control for the Alfisol. Spodosols appeared to respond to any additional fertilization compared to the control group regardless of rate. Importantly, we found that O horizon mass and P content from the first rotation, approximately seven years before harvest, exhibited a positive linear relationship with one-year-old heights in the Spodosol and one- and two-year-old heights in the Alfisol. These findings shed light on the importance of the O horizon characteristics and its potential as an indicator for tree growth in subsequent rotations.}, journal={FOREST ECOLOGY AND MANAGEMENT}, publisher={Elsevier BV}, author={Hackman, Jacob and Cook, Rachel and Strahm, Brian and Carter, David and Woodley, Alex and Garcia, Kevin and Albaugh, Timothy and Rubilar, Rafael and Campoe, Otavio}, year={2024}, month={Mar} }
 @article{cook_fox_allen_cohrs_ribas-costa_trlica_ricker_carter_rubilar_campoe_et al._2024, title={Forest soil classification for intensive pine plantation management: "Site Productivity Optimization for Trees" system}, volume={556}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2024.121732}, abstractNote={Forest productivity and response to silvicultural treatments are dependent on inherent site resource availability and limitations. Trees have deeper rooting profiles than agronomic crops, so evaluating the impacts of soils, geology, and physiographic province on forest productivity can help guide silvicultural management decisions in southern pine plantations. Here, we describe the Forest Productivity Cooperative’s “Site Productivity Optimization for Trees” (SPOT) system which includes: texture, depth to increase in clay content, drainage class, soil modifiers (i.e., surface attributes, mineralogy, and additional limitations such as root restrictions), geologic formations, and physiographic province. We quantified the total area for each SPOT code in the native range of loblolly pine (Pinus taeda L.), the region’s most commercially important species, and used a remotely-sensed layer to quantify SPOT code areas in managed southern pine (approximately 14 million ha). The most common SPOT code in the native range is also the most planted, a B2WekoGgPD (fine loamy, shallow depth to increase in clay, well-drained, eroded, kaolinitic, granitic, Piedmont soil), spanning 1.1 million ha total, but only 12% in managed southern pine. However, the SPOT code with the greatest percentage of managed southern pine (61%; a D4PoioAmAF, spodic, deep to increase in clay, siliceous, middle Atlantic Coastal Plain, Flatwoods soil) was the 20th most common in the native range with 474,662 ha. We used machine learning and data from decades of “Regionwide” trials to assess the variable importance of SPOT constituents, climate, planting year, and N rate on site index (base age 25 years) and found that planting year was the most important variable, showing an increase of 17 cm site index per year since 1970, followed by maximum vapor pressure deficit, and precipitation. Geology was the top-ranking SPOT variable to explain site index followed by physiographic province. The Regionwide trials represent 72 unique SPOT codes (out of over 10,000 possible in the pine plantations) and approximately one million ha (or about 7% of all soils identified as supporting managed pine). To extrapolate site index values outside of the unique soil and geologic conditions empirically represented, we created a predictive model with an R2 of 0.79 and an RMSE of 1.38 m from SPOT codes alone. With this extrapolation, the Regionwide data predicts 10.5 million ha, or 74%, of all soils under loblolly pine management in its native range. Overall, this system will allow managers to assess their current site productivity, and recommend silvicultural treatments, thus, providing a framework to optimize forest productivity in pine plantations in the southeastern US.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Cook, Rachel and Fox, Thomas R. and Allen, Howard Lee and Cohrs, Chris W. and Ribas-Costa, Vicent and Trlica, Andrew and Ricker, Matthew and Carter, David R. and Rubilar, Rafael and Campoe, Otavio and et al.}, year={2024}, month={Mar} }
 @article{sumnall_albaugh_carter_cook_hession_campoe_rubilar_wynne_thomas_2023, title={Estimation of individual stem volume and diameter from segmented UAV laser scanning datasets in Pinus taeda L. plantations}, volume={44}, ISSN={["1366-5901"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85148453201&partnerID=MN8TOARS}, DOI={10.1080/01431161.2022.2161853}, abstractNote={ABSTRACT The competitive neighbourhood surrounding an individual tree can have a significant influence on its diameter at breast height (DBH) and individual tree stem volume (SV). Distance dependent competition index metrics are rarely recorded in traditional field campaigns because they are laborious to collect and are spatially limited. Remote sensing data could overcome these limitations while providing estimation of forest attributes over a large area. We used unoccupied aerial vehicle laser scanning data to delineate individual tree crowns (ITCs) and calculated crown size and distance-dependent competition indices to estimate DBH and SV. We contrasted two methods: (i) Random Forest (RF) and (ii) backwards-stepwise, linear multiple regression (LMR). We utilized an existing experiment in Pinus taeda L. plantations including multiple planting densities, genotypes and silvicultural levels. While the tree planting density did affect the correct delineation of ITCs, between 61% and 99% (mean 86%) were correctly linked to the planting location. The most accurate RF and LMR models all included metrics related to ITC size and competitive neighbourhood. The DBH estimates from RF and LMR were similar: RMSE 3.05 and 3.13 cm (R2 0.64 and 0.62), respectively. Estimates of SV from RF were slightly better than for LMR: RMSE 0.06 and 0.07 m3 (R2 0.77 and 0.70), respectively. Our results provide evidence that ITC size and competition index metrics may improve DBH and SV estimation accuracy when analysing laser-scanning data. The ability to provide accurate, and near-complete, forest inventories holds a great deal of potential for forest management planning.}, number={1}, journal={INTERNATIONAL JOURNAL OF REMOTE SENSING}, author={Sumnall, Matthew J. J. and Albaugh, Timothy J. J. and Carter, David R. R. and Cook, Rachel L. L. and Hession, W. Cully and Campoe, Otavio C. and Rubilar, Rafael A. A. and Wynne, Randolph H. H. and Thomas, Valerie A. A.}, year={2023}, month={Jan}, pages={217–247} }
 @article{rubilar_bozo_albaugh_cook_campoe_carter_allen_alvarez_pincheira_zapata_2023, title={Rotation-age effects of subsoiling, fertilization, and weed control on radiata pine growth at sites with contrasting soil physical, nutrient, and water limitations}, volume={544}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2023.121213}, abstractNote={Although short- and medium-term responses to early silvicultural treatments have been documented, few studies show productivity gains or losses throughout a rotation across a range of soil types and resource availability. We evaluated the rotation length productivity responses of radiata pine to subsoiling, fertilization, and weed control in dry sand (DS), red clay (RC), and recent volcanic ash (RV) soils representing a gradient of physical, nutrient, and water limitations. Stands were planted in 2000 in a split-plot factorial design, with soil preparation (subsoiling vs. shovel planting) as the main plot and fertilization at planting (B only vs. NPKB) and weed control (none vs. 2-year banded application) as factorial randomized treatment plots within the main plots. Annual diameter at breast height, height, survival, and cumulative volume responses were measured. The rotation-age results for cumulative volume showed that early gains from weed control were maintained through at least 15 years of age. At rotation age, weed control increased the cumulative volume at the DS site (56 m3/ha, 20% gain), and the response over time was maintained at the RC site (28 m3/ha, 8% gain), whereas the volume was reduced at the RV site (-36 m3/ha, 7% loss). Fertilization resulted in the greatest response at the RC site (29 m3/ha, 8% gain); there were small responses at the DS site (5 m3/ha, 2% gain) and negative responses at the RV site (-18 m3/ha, 4% loss). Interestingly, subsoiling resulted in null or negative responses at all sites, and negative effects increased over time, with volume responses ranging from −4 m3/ha (1% loss) and −27 m3/ha (7% loss) at the DS and RC sites, respectively, to −116 m3/ha (21% loss) at the RV site. Carrying capacity was reached at mid-rotation at the RV site and resulted in negative treatment effects at rotation age, suggesting the need for thinning or a younger harvest age at this site. Given the negative or null effects of soil preparation, a better understanding is needed for how this silvicultural treatment is affected by soil type and soil strength.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Rubilar, Rafael and Bozo, Daniel and Albaugh, Timothy and Cook, Rachel and Campoe, Otavio and Carter, David and Allen, H. Lee and Alvarez, Jose and Pincheira, Matias and Zapata, Alvaro}, year={2023}, month={Sep} }
 @article{sumnall_albaugh_carter_cook_hession_campoe_rubilar_wynne_thomas_2022, title={Effect of varied unmanned aerial vehicle laser scanning pulse density on accurately quantifying forest structure}, volume={43}, ISSN={["1366-5901"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85123921158&partnerID=MN8TOARS}, DOI={10.1080/01431161.2021.2023229}, abstractNote={ABSTRACT Airborne laser scanning (ALS) is increasingly used to estimate various forest characteristics. Technological improvements in unmanned aerial vehicles (UAVs) and drone laser scanning (DLS) sensors have permitted the acquisition of high pulse density datasets. There is an assumption that higher pulse densities yield greater accuracies in estimating forest characteristics. In this study, we investigated the effect of pulse density (.25, .5, 1, 5, 10, 50, 100 and 300 pulses m−2) on the ability to delineate individual tree crowns (ITCs) and estimate ITC height and crown horizontal diameter, in addition to plot-level leaf area index (LAI). The current study took place in an experimentally varied Pinus taeda L. forest, which included three stem densities: (i) 618; (ii) 1236; and (iii) 1853 trees per hectare (TPH). ITCs were classified directly from the DLS point cloud for each of the pulse densities. The correct delineation of ITCs relative to field tree-coordinates was relatively consistent (±5%) for pulse densities of 5 to 300 pulses m−2. ITC delineation accuracy decreased with lower pulse densities. Planting stem density did impact ITC delineation accuracy. Higher pulse densities, plots with 618 TPH correctly classified ~88% of ITCs, and plots with the 1853 TPH correctly classified ~50% of ITCs. Estimates of tree height were largely unaffected by changes in tree density. Root mean square error (RMSE) for tree height varied from .5 to 2.5 m at pulse densities of 300 to .25 pulses m−2, respectively. Estimates of crown horizontal diameter varied with regard to both pulse and stem density from 1.2 (300 ppm−2 and 1853 TPH) to 4.2 m (.25 ppm−2 and 618 TPH). RMSE varied among stem densities from .6 to 1.2 m as pulse density decreased. There was significant difference in ITC delineation accuracy, particularly when considering stem density, and the estimates of tree height and crown horizontal diameter among the DLS pulse densities used. The accuracy of predicted LAI was largely unaffected by changes in pulse density, when pulse density was above .5 pulses m−2. There was little or no difference in estimates of LAI at these pulse densities. Our results suggest that low-density DLS data may be capable of estimating plot-level forest metrics reliably in some situations, however once the analysis scale is reduced to the individual-tree-level, the influence of pulse density is more substantial. The results here provide guidance to forest managers who must balance metric estimation accuracy and price when planning new ALS or DLS acquisitions.}, number={2}, journal={INTERNATIONAL JOURNAL OF REMOTE SENSING}, author={Sumnall, Matthew J. and Albaugh, Timothy J. and Carter, David R. and Cook, Rachel L. and Hession, W. Cully and Campoe, Otavio C. and Rubilar, Rafael A. and Wynne, Randolph H. and Thomas, Valerie A.}, year={2022}, month={Jan}, pages={721–750} }
 @article{albaugh_carter_cook_campoe_rubilar_creighton_2022, title={Improving Pinus taeda site index from rotation to rotation with silvicultural treatments}, volume={526}, ISSN={["1872-7042"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85139855986&partnerID=MN8TOARS}, DOI={10.1016/j.foreco.2022.120581}, abstractNote={We wanted to improve site index using fertilizer applications and planting density at a site with a site index of 16.8 m at a base age of 25 years. We installed a randomized complete block study in the Virginia Piedmont with three replications of three levels of fertilization (cumulative elemental nitrogen and phosphorous amounts of 0 and 45, 309 and 73, and 787 and 129 kg ha−1, respectively) and two levels of planting density (896 and 1793 trees ha−1). We measured the stand 15 times and completed our analysis after age 22 measurements. Fertilization and planting density did not affect site index and there was no planting density by fertilization interaction. Fertilizer significantly increased stem diameter and basal area but did not affect dominant height. Low planting density resulted in significantly larger diameter trees with longer crowns, but with less basal area and stand scale production than the high planting density. However, site index in all treatments improved to 24.2 m, a 7.4 m increase from one rotation to the next. We attributed the increase in site index to adding the primary limiting resource (phosphorous), better competition control, genetics and growing environment. Silvicultural inputs and environmental conditions influence site index and estimates of productivity (e.g. m3 ha−1 yr−1) may be more useful.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Albaugh, Timothy J. and Carter, David R. and Cook, Rachel L. and Campoe, Otavio C. and Rubilar, Rafael A. and Creighton, Jerre L.}, year={2022}, month={Dec} }
 @article{shively_cook_maier_garcia_albaugh_campoe_leggett_2022, title={Readily available resources across sites and genotypes result in greater aboveground growth and reduced fine root production in Pinus taeda}, volume={521}, ISSN={["1872-7042"]}, url={http://europepmc.org/abstract/AGR/IND607837981}, DOI={10.1016/j.foreco.2022.120431}, abstractNote={Fine roots serve as the primary interface between trees and the soil, and they are dynamic in their response to environmental conditions.Among many functions, they are principle in gathering nutrients and water, and they constitute a major component of the tree.Their overall contribution to soil carbon flux is not well understood, nor is the effect of site and genotype on their dynamics, and these factors are crucial to understanding nutrient cycles and tree growth under variable conditions.This study evaluated how the fine root dynamics of loblolly pine (Pinus taeda L.) might be different between genotypes and on different sites.Three loblolly pine plantations were established, two in 2009 in North Carolina (NC) and Virginia (VA), and one in 2011 in Brazil (BR).Root biomass was estimated with soil cores across the three sites and between two genotypes in 2020.Seasonal and annual fine root production was measured at the NC and VA sites over the 12th growing season using ingrowth cores.The trees in BR that were two years younger were much larger than those in NC and VA and had more fine root biomass at initial sampling than those in NC, despite similar levels of fertility.Meanwhile, fine root production rates decreased with higher rates of aboveground productivity across all measured plots in NC and VA.These results indicate that (1) standing fine root biomass may be related to environmental conditions that are not easily manipulated, which could inform modeling of carbon cycles, and (2) in these intensively managed plots, sufficient resources were available to allow for increased aboveground growth despite lower rates of fine root production, which supports the employment of these intensive silvicultural practices.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Shively, Timothy J. and Cook, Rachel and Maier, Chris A. and Garcia, Kevin and Albaugh, Timothy J. and Campoe, Otavio and Leggett, Zakiya}, year={2022}, month={Oct} }
 @article{albaugh_albaugh_carter_cook_cohrs_rubilar_campoe_2021, title={Duration of response to nitrogen and phosphorus applications in mid-rotation Pinus taeda}, volume={498}, ISSN={["1872-7042"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85112486933&partnerID=MN8TOARS}, DOI={10.1016/j.foreco.2021.119578}, abstractNote={We quantified the response duration to one-time applications of 112, 224, and 336 kg ha−1 of elemental nitrogen (112 N, 224 N, and 336 N, respectively) combined with 28 or 56 kg ha−1 of elemental phosphorus in mid-rotation Pinus taeda L. stands. Post-application measurements continued for 10 years at 32 sites in the southeastern United States and one site in Argentina, and we fit a Ricker model to data from each treatment in the event that a zero growth response was not observed in our measured data. The response duration was eight (measured), 14 (modeled), and 16 (modeled) years after treatment for the respective 112 N, 224 N, and 336 N treatments. The corresponding growth response per unit of applied nitrogen estimated from fertilization to when the growth response was not different from zero (whether measured or modeled) was 0.20, 0.16, and 0.13 m3 kg−1 for the 112 N, 224 N, and 336 N treatments, respectively. We hypothesized that the mechanism controlling the response duration was related to the amount of fertilizer nitrogen remaining in the foliage over time after treatment; previous studies found that nitrogen application had large impacts on the foliage amount and foliar nitrogen content. Based on retranslocation rate estimates from the literature of 67% of fertilizer nitrogen per year, our results suggest that a good correlation exists between the growth response and the amount of fertilizer nitrogen remaining in the foliage.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Albaugh, Timothy J. and Albaugh, Janine M. and Carter, David R. and Cook, Rachel L. and Cohrs, Chris W. and Rubilar, Rafael A. and Campoe, Otavio C.}, year={2021}, month={Oct} }
 @article{grover_cook_zapata_urrego_albaugh_zelaya_ozyhar_rubilar_carter_campoe_2021, title={Eucalyptus grandis Response to Calcium Fertilization in Colombia}, volume={67}, ISSN={["1938-3738"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85121035283&partnerID=MN8TOARS}, DOI={10.1093/forsci/fxab042}, abstractNote={
 Calcium (Ca) is a critical plant nutrient typically applied at the time of planting in intensive Eucalyptus plantations in South America. At two sites in Colombia, we examined (1) calcium source by comparing growth after application of 100 kg ha−1 elemental Ca as lime or as pelletized highly reactive calcium fertilizer (HRCF) compared to a no application control, and (2) Ca rate by applying 0, 100, 200, and 400 kg ha−1 elemental Ca as HRCF with the addition of nitrogen, phosphorus, potassium, sulfur, and boron (NPKSB). We assessed height, diameter, and volume after 12 and 24 months. There were no growth differences from Ca source at the 100 kg ha−1 rate. We found increased volume after 24 months at the “Popayan” site with 200 and 400 kg ha−1 Ca HRCF+NPKSB treatments (112 and 113 m3 ha−1, respectively) compared to control (92 m3 ha−1), a 22% increase. In contrast, volume did not differ after 24 months at the “Darien” site, ranging from 114 m3 ha−1 in the 0 kg ha−1 Ca HRCF+NPKSB treatment to 98 m3 ha−1 in the control. Differences in response are likely due to soil characteristics, such as organic matter, emphasizing the importance of identifying site-specific nutrient deficiencies.
 Study Implications: Operational applications may be over- or under-applying calcium carbonate in Eucalyptus plantations in South America. In the first two years of a seven-year rotation located in volcanic soils in Colombia, we found that one site with more organic matter at a greater depth did not need Ca additions, whereas the other site required greater than current operational applications to optimize productivity. Ca application rate trials across a gradient of soil conditions could establish critical values and improve recommendations of appropriate Ca application rates and emphasize the importance of understanding site-specific soil conditions to produce effective fertilization regimes.}, number={6}, journal={FOREST SCIENCE}, author={Grover, Zach S. and Cook, Rachel L. and Zapata, Marcela and Urrego, J. Byron and Albaugh, Timothy J. and Zelaya, Ariel and Ozyhar, Tomasz and Rubilar, Rafael and Carter, David R. and Campoe, Otavio C.}, year={2021}, month={Dec}, pages={701–710} }
 @article{trlica_cook_albaugh_parajuli_carter_rubilar_2021, title={Financial Returns for Biomass on Short-Rotation Loblolly Pine Plantations in the Southeastern United States}, volume={67}, ISSN={["1938-3738"]}, url={https://doi.org/10.1093/forsci/fxab033}, DOI={10.1093/forsci/fxab033}, abstractNote={
 Rising demand for renewable energy has created a potential market for biomass from short-rotation pine plantations in the southeastern United States. Site preparation, competition control, fertilization, and enhanced seedling genotypes offer the landowner several variables for managing productivity, but their combined effects on financial returns are unclear. This study estimated returns from a hypothetical 10-year biomass harvest in loblolly pine plantation using field studies in the Coastal Plain of North Carolina and the Virginia Piedmont testing combinations of tree genotype, planting density, and silviculture. Although enhanced varietal genotypes could yield more biomass, open-pollinated seedlings at 1,236–1,853 trees ha−1 under operational silviculture had the greatest returns at both sites, with mean whole-tree internal rates of return of 8.3%–9.9% assuming stumpage equal to current pulpwood prices. At a 5% discount rate, break-even whole-tree stumpage at the two sites in the optimal treatments was $8.72–$9.92 Mg−1, and break-even yield was 175–177 Mg ha−1 (roughly 18 Mg ha−1 yr−1 productivity), although stumpage and yield floors were higher if only stem biomass was treated as salable. Dedicated short-rotation loblolly biomass plantations in the region are more likely to be financially attractive when site establishment and maintenance costs are minimized.
 Study Implications: Our study suggests that dedicated loblolly pine plantations in the US Southeast may be managed to generate positive financial yields for biomass over relatively short (10 year) rotation windows, even at lower stumpage value than at present for pulpwood in the region (<80% current). Intensive use of costly inputs like fertilizer, vigorous chemical competition control, and elite genetics in planting stock did improve biomass yields. However, the management combinations that favored the highest financial returns emphasized the least expensive open-pollinated stock, lower-input operational silviculture, and moderate-to-high planting density.}, number={6}, journal={FOREST SCIENCE}, publisher={Oxford University Press (OUP)}, author={Trlica, Andrew and Cook, Rachel L. and Albaugh, Timothy J. and Parajuli, Rajan and Carter, David R. and Rubilar, Rafael A.}, year={2021}, month={Dec}, pages={670–681} }
 @article{gao_gray_cohrs_cook_albaugh_2021, title={Longer greenup periods associated with greater wood volume growth in managed pine stands}, volume={297}, ISSN={["1873-2240"]}, url={https://doi.org/10.1016/j.agrformet.2020.108237}, DOI={10.1016/j.agrformet.2020.108237}, abstractNote={Increasing forest productivity is important to meet future demand for forest products, and to improve resilience in the face of climate change. Forest productivity depends on many things, but the timing of leaf development (hereafter: “plant phenology”) is especially important. However, our understanding of how plant phenology affects the productivity of managed forests, and how silviculture may in turn affect phenology, has been limited because of the spatial scale mismatch between phenological data and field experimental observations. In this study, we take advantage of a new 30 m satellite land surface phenology dataset and stand growth measurements from long-term experimental pine plantation sites in the southeastern United States to investigate the question: is stand growth related to remotely sensed phenology metrics? Multiple linear regression and random forest models were fitted to quantify the effect of phenology and silvicultural treatments on stand growth. We found that 1) Greater wood volume growth was associated with longer green up periods; 2) Fertilization elevated EVI2 measurement values during the whole growing season, especially in the winter; 3) Competing vegetation could affect remotely sensed observations and complicates interpretation of remotely sensed phenology metrics.}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, publisher={Elsevier BV}, author={Gao, Xiaojie and Gray, Josh and Cohrs, Chris W. and Cook, Rachel and Albaugh, Timothy J.}, year={2021}, month={Feb} }
 @article{scolforo_montes_cook_allen_albaugh_rubilar_campoe_2020, title={A New Approach for Modeling Volume Response from Mid-Rotation Fertilization ofPinus taedaL. Plantations}, volume={11}, ISSN={["1999-4907"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85087994086&partnerID=MN8TOARS}, DOI={10.3390/f11060646}, abstractNote={Mid-rotation fertilization presents an opportunity to increase the economic return of plantation forests in the southeastern United States (SEUS). For this reason, the Forest Productivity Cooperative established a series of mid-rotation fertilization trials in Pinus taeda L. plantations across the SEUS between 1984 and 1987. These trials identified site-specific responses to nitrogen (N) and phosphorus (P) fertilizers, resulting in increased stand production for 6–10 years after fertilization. There are successful volume response models that allow users to quantify the gain in stand productivity resulting from fertilization. However, all the current models depend on empirical relationships that are not bounded by biological response, meaning that greater fertilizer additions continue to create more volume gains, regardless of physiological limits. To address this shortcoming, we developed a bounded response model that evaluates relative volume response gain to fertilizer addition. Site index and relative spacing are included as model parameters to help provide realistic estimates. The model is useful for evaluating productivity gain in Pinus taeda stands that are fertilized with N and P in mid-rotation.}, number={6}, journal={FORESTS}, author={Scolforo, Henrique F. and Montes, Cristian and Cook, Rachel L. and Allen, Howard Lee and Albaugh, Timothy J. and Rubilar, Rafael and Campoe, Otavio}, year={2020}, month={Jun} }
 @article{albaugh_maier_campoe_yanez_carbaugh_carter_cook_rubilar_fox_2020, title={Crown architecture, crown leaf area distribution, and individual tree growth efficiency vary across site, genetic entry, and planting density}, volume={34}, ISSN={["1432-2285"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85071645632&partnerID=MN8TOARS}, DOI={10.1007/s00468-019-01898-3}, abstractNote={We examined crown architecture and within crown leaf area distribution effects on Pinus taeda L. growth in North Carolina (NC), Virginia (VA), and Brazil (BR) to better understand why P. taeda can grow much better in Brazil than in the southeastern United States. The NC, VA, and BR sites were planted in 2009, 2009, and 2011, respectively. At all sites, we planted the same two genetic entries at 618, 1236, and 1854 trees ha−1. In 2013, when trees were still open grown, the VA and NC sites had greater branch diameter (24%), branch number (14%), live crown length (44%), foliage mass (82%), and branch mass (91%), than the BR site. However, in 2017, after crown closure and when there was no significant difference in tree size, site did not significantly affect these crown variables. In 2013, site significantly affected absolute leaf area distribution, likely due to differences in live crown length and leaf area, such that there was more foliage at a given level in the crown at the VA and NC sites than at the BR site. In 2017, site was still a significant factor explaining leaf area distribution, although at this point, with crown closure and similar sized trees, there was more foliage at the BR site at a given level in the crown compared to the VA and NC sites. In 2013 and 2017, when including site, genetic entry, stand density, and leaf area distribution parameters as independent variables, site significantly affected individual tree growth efficiency, indicating that something other than leaf area distribution was influencing the site effect. Better BR P. taeda growth is likely due to a combination of factors, including leaf area distribution, crown architecture, and other factors that have been identified as influencing the site effect (heat sum), indicating that future work should include a modeling analysis to examine all known contributing factors.}, number={1}, journal={TREES-STRUCTURE AND FUNCTION}, author={Albaugh, Timothy J. and Maier, Chris A. and Campoe, Otavio C. and Yanez, Marco A. and Carbaugh, Eric D. and Carter, David R. and Cook, Rachel L. and Rubilar, Rafael A. and Fox, Thomas R.}, year={2020}, month={Feb}, pages={73–88} }
 @article{raymond_fox_cook_albaugh_rubilar_2020, title={Losses of fertilizer nitrogen after a winter fertilization in three managed pine plantations of the southeastern United States}, volume={84}, ISSN={["1435-0661"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85081895628&partnerID=MN8TOARS}, DOI={10.1002/saj2.20017}, abstractNote={Abstract Losses of fertilizer nitrogen (N) were compared between urea and urea treated with the urease inhibitor N‐(n‐Butyl) thiophosphoric triamide (urea + NBPT) after a surface application in winter at three thinned mid‐rotation (age 15–20 years) loblolly pine plantations in Virginia, South Carolina, and Florida. Treatments were labeled with 15 N and applied to open chamber microcosms in January and February 2016. Fifteen days after application, microcosms were removed from the field to determine fertilizer N lost from each microcosm. Losses following fertilization with urea (24% to 50%) were greater ( p ≥ .05) at all sites compared to urea + NBPT (12% to 22%). Fertilizer N losses were greater in Florida than in SC and Virginia although N loss following urea fertilization was still 25% in Virginia. The loss of fertilizer N was consistently lower on beds compared to interbeds for both urea (bed = 25%, interbed = 40%) and urea + NBPT (bed = 12%, interbed = 23%). This research highlights the value of using urea + NBPT to reduce fertilizer N losses after a winter application and the greater potential loss in the interbed on wetter sites.}, number={2}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Raymond, Jay E. and Fox, Thomas R. and Cook, Rachel L. and Albaugh, Timothy J. and Rubilar, Rafael}, year={2020}, pages={609–617} }
 @article{schulte_cook_albaugh_allen_rubilar_pezzutti_lucia caldato_campoe_carter_2020, title={Mid-rotation response of Pinus taeda to early silvicultural treatments in subtropical Argentina}, volume={473}, ISSN={["1872-7042"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85086739488&partnerID=MN8TOARS}, DOI={10.1016/j.foreco.2020.118317}, abstractNote={Pinus taeda plantations in subtropical areas of South America are extremely productive and commonly established on well-drained red clay sites. In the past, land with more poorly-drained soil was avoided due to concern over the factors limiting site productivity. Establishment of intensively managed plantations on poorly-drained soils usually includes soil preparation by subsoiling and/or bedding, weed control, and fertilization. However, forest managers lack information about the efficacy of early silvicultural practices to ameliorate environmental limitations and if these intensive practices generate long-term improvements in productivity in this area. Consequently, we established studies in northeastern Argentina on two sites differing by drainage class and soil texture as a full factorial design with site preparation (S; disking and disking + subsoiling (red clay) or bedding (wet loam)), fertilization (F; none or 78 kg ha−1 elemental phosphorus at planting), and weed control (W; none or two-year banded). Seven years after planting, the red clay and wet loam sites were equally productive, with maximum treatment means of 218 m3 ha−1 and 264 m3 ha−1 respectively. At the red clay site, only weed control significantly increased volume. At the wet loam site, both weed control and site preparation significantly increased volume, mainly due to increased survival. The combination of weed control and bedding yielded a non-additive volume response as indicated by a significant W*S interaction. Our results do not support the common practice of subsoiling on red clay soils. In addition, fertilization with P alone appears counterproductive or unneeded at both sites.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Schulte, Morgan L. and Cook, Rachel L. and Albaugh, Timothy J. and Allen, H. Lee and Rubilar, Rafael A. and Pezzutti, Raul and Lucia Caldato, Silvana and Campoe, Otavio and Carter, David R.}, year={2020}, month={Oct} }
 @article{cohrs_cook_gray_albaugh_2020, title={Sentinel-2 Leaf Area Index Estimation for Pine Plantations in the Southeastern United States}, volume={12}, ISSN={2072-4292}, url={http://dx.doi.org/10.3390/rs12091406}, DOI={10.3390/rs12091406}, abstractNote={Leaf area index (LAI) is an important biophysical indicator of forest health that is linearly related to productivity, serving as a key criterion for potential nutrient management. A single equation was produced to model surface reflectance values captured from the Sentinel-2 Multispectral Instrument (MSI) with a robust dataset of field observations of loblolly pine (Pinus taeda L.) LAI collected with a LAI-2200C plant canopy analyzer. Support vector machine (SVM)-supervised classification was used to improve the model fit by removing plots saturated with aberrant radiometric signatures that would not be captured in the association between Sentinel-2 and LAI-2200C. The resulting equation, LAI = 0.310SR − 0.098 (where SR = the simple ratio between near-infrared (NIR) and red bands), displayed good performance ( R 2 = 0.81, RMSE = 0.36) at estimating the LAI for loblolly pine within the analyzed region at a 10 m spatial resolution. Our model incorporated a high number of validation plots (n = 292) spanning from southern Virginia to northern Florida across a range of soil textures (sandy to clayey), drainage classes (well drained to very poorly drained), and site characteristics common to pine forest plantations in the southeastern United States. The training dataset included plot-level treatment metrics—silviculture intensity, genetics, and density—on which sensitivity analysis was performed to inform model fit behavior. Plot density, particularly when there were ≤618 trees per hectare, was shown to impact model performance, causing LAI estimates to be overpredicted (to a maximum of X i + 0.16). Silviculture intensity (competition control and fertilization rates) and genetics did not markedly impact the relationship between SR and LAI. Results indicate that Sentinel-2’s improved spatial resolution and temporal revisit interval provide new opportunities for managers to detect within-stand variance and improve accuracy for LAI estimation over current industry standard models.}, number={9}, journal={Remote Sensing}, publisher={MDPI AG}, author={Cohrs, Chris W. and Cook, Rachel L. and Gray, Josh M. and Albaugh, Timothy J.}, year={2020}, month={Apr}, pages={1406} }
 @article{albaugh_albaugh_heiderman_leggett_stape_king_katherine p. o'neill_king_2014, title={Evaluating changes in switchgrass physiology, biomass, and light-use efficiency under artificial shade to estimate yields if intercropped with Pinus taeda L.}, volume={88}, ISSN={["1572-9680"]}, DOI={10.1007/s10457-014-9708-3}, number={3}, journal={AGROFORESTRY SYSTEMS}, author={Albaugh, Janine M. and Albaugh, Timothy J. and Heiderman, Ryan R. and Leggett, Zakiya and Stape, Jose L. and King, Kyle and Katherine P. O'Neill and King, John S.}, year={2014}, month={Jun}, pages={489–503} }
 @article{carlson_fox_allen_albaugh_rubilar_stape_2014, title={Growth Responses of Loblolly Pine in the Southeast United States to Midrotation Applications of Nitrogen, Phosphorus, Potassium, and Micronutrients}, volume={60}, ISSN={["1938-3738"]}, DOI={10.5849/forsci.12-158}, abstractNote={Growth of midrotation pine plantations in the southeast United States tends to be limited by nitrogen (N) and phosphorus (P). Routine applications of urea and diammonium phosphate ameliorate N and P deficiencies; however, questions concerning what other nutrients are likely to be limiting growth are being raised. Consequently, a trial series with 23 study installations was established in loblolly (Pinus taeda L.) stands, aged between 9 and 25 years, with the aim of determining whether stands would respond to potassium (K) additions once the N and P deficiencies were corrected and whether the application of a full suite of macro- and micronutrients would further increase growth. On average, N plus P applications resulted in a mean growth improvement over unfertilized controls of 3.71 m3 ha−1 year−1 for 8 years after fertilization. Further growth improvements in response to the application of K, either with the N and P, or together with a range of macro- and micronutrients, were found to be dependent on location. Studies located on Pleistocene terraces, between 10 and 65 m in elevation, associated with ancient sea levels including the Talbot, Penholloway, Wicomico, Sunderland, and Coharie terraces of Georgia and the Carolinas, showed a smaller than average positive response to the addition of N and P (2.66 m3 ha−1 year−1), with further increases in growth when K was applied as well (additional 1.33 m3 ha−1 year−1) and a further increase when a complete suite of nutrients was added (additional 2.59 m3 ha−1 year−1). Studies located elsewhere in the South showed an average response to the addition of N and P (mean improvement of 4.28 m3 ha−1 year−1), with no improvement in growth when additional nutrients were added. These results can assist foresters in identifying stands that are potentially responsive to applications of nutrients other than N and P.}, number={1}, journal={FOREST SCIENCE}, author={Carlson, Colleen A. and Fox, Thomas R. and Allen, H. Lee and Albaugh, Timothy J. and Rubilar, Rafael A. and Stape, Jose L.}, year={2014}, month={Feb}, pages={157–169} }
 @article{albaugh_fox_blinn_allen_rubilar_stape_2013, title={Developing a new foliar nutrient-based method to predict response to competing vegetation control in Pinus taeda}, volume={37}, number={4}, journal={Southern Journal of Applied Forestry}, author={Albaugh, T. J. and Fox, T. R. and Blinn, C. E. and Allen, H. L. and Rubilar, R. A. and Stape, J. L.}, year={2013}, pages={196–201} }
 @article{alvarez_allen_albaugh_stape_bullock_song_2013, title={Factors influencing the growth of radiata pine plantations in Chile}, volume={86}, DOI={10.1093/forestry/cps072}, abstractNote={We examined environmental factors affecting growth rates of Pinus radiata in Chile. The relationships between annual volume growth and soil, climate, canopy and stand factors were analysed using data from 48 permanent sample plots in P. radiata plantations in central Chile. Water availability (as affected by precipitation, soil water holding capacity and potential evapotranspiration) appeared to be the factor most limiting to leaf area and growth. Maximum growing season temperature also negatively affected growth. Sites with the highest productivities had the lowest annual water deficits. The most productive sites used water and light more efficiently. Growth per unit of potential evapotranspiration ranged from 0.5 to 1.6 kg of wood per m 3 of water and growth per unit of radiation ranged from 0.3 to 0.5 g of wood per MJ of photosynthetically active radiation for low and high productivity sites. The inclusion of simple climatic variables such as maximum temperature and precipitation into Chilean P. radiata growth and yield models should improve their performance.}, number={1}, journal={Forestry}, author={Alvarez, J. and Allen, Howard and Albaugh, T. J. and Stape, J. L. and Bullock, B. P. and Song, C.}, year={2013}, pages={13–26} }
 @article{campoe_stape_albaugh_allen_fox_rubilar_binkley_2013, title={Fertilization and irrigation effects on tree level aboveground net primary production, light interception and light use efficiency in a loblolly pine plantation}, volume={288}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2012.05.026}, abstractNote={Fertilization and irrigation may substantially increase productivity of forests by increasing stand leaf area index and the efficiency of converting intercepted light into wood biomass. This stand-level growth response is the summation of individual tree responses, and these tree-level responses are often non-linear, resulting from shifting in the intensity of competition and dominance. We examined tree-level responses of aboveground net primary production (ANPP), absorbed photosynthetically active radiation (APAR) and (light use efficiency) LUE in relation to tree size class to explore how stand-level outcomes depend on shifting patterns among trees. We evaluated the production ecology of a nine-year-old loblolly pine (Pinus taeda L.) plantation, 2 years after the initiation of treatments: control, irrigation, fertilization and irrigation + fertilization. We measured tree level ANPP, simulated APAR for individual tree crowns using the MAESTRA process-based model and calculated LUE (ANPP/APAR) in relation to tree size to explore the influence of tree dominance on both light capture and light use efficiency. Fertilization and irrigation + fertilization strongly increased both APAR and LUE, in contrast to little effect of irrigation alone. Tree size had a strong influence on APAR and LUE across all treatments; the largest 20% trees showed 3.4 times greater ANPP when compared to the smallest 20% trees, with 66% resulting from higher APAR, and 34% from higher LUE, than the smallest 20% of trees. Fertilization increased the growth of the largest 20% trees 2-fold (8.6 kg tree−1 year−1), with 29% of the increase resulting from higher APAR (13.7 GJ tree−1 year−1), and 71% from higher LUE (0.63 g MJ−1), relative to the largest trees in the control treatment (4.3 kg tree−1 year−1, 11 GJ tree−1 year−1 and 0.39 g MJ−1, respectively). Irrigation and fertilization tripled production (13.2 kg tree−1 year−1) of the largest trees with an even greater proportional contribution from increased LUE (15.1 GJ tree−1 year−1, 85% response contribution; APAR 0.87 g MJ−1, 15% response contribution). Overall, large trees grow faster than smaller trees because of greater light capture, whereas the greater response of large trees to treatments resulted more from increased efficiency of using light.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Campoe, Otavio C. and Stape, Jose Luiz and Albaugh, Timothy J. and Allen, H. Lee and Fox, Thomas R. and Rubilar, Rafael and Binkley, Dan}, year={2013}, month={Jan}, pages={43–48} }
 @article{rubilar_albaugh_allen_alvarez_fox_stape_2013, title={Foliage development and leaf area duration in Pinus radiata}, volume={304}, ISSN={["0378-1127"]}, DOI={10.1016/j.foreco.2013.05.044}, abstractNote={Abstract Site-specific constraints on foliage development and leaf area duration were investigated in two-year-old Pinus radiata D. Don. plantations established under a factorial combination of soil tillage (shovel vs. subsoil + bedding + shovel), fertilization (B only vs. N, P, K, and B), and weed control (pre-plant vs. pre-plant + two-year banded) at three contrasting textural (sand, clay and ash) and climatic soil-site conditions in the Central Valley of Chile. We examined site effects and five treatments at each site to test hypotheses that soil tillage and nutrient and water limitations, would not influence foliage development or leaf area duration. Site effects were evident for foliage development and leaf area duration. Improved nutrient availability increased fascicle length at the sand and clay sites. Improved water availability increased fascicle length and leaf area duration at the sand site, and increased fascicle number at the sand and clay sites. Soil tillage reduced fascicle length at the ash site. Fascicle length may be influenced by factors including water and nutrient availability and soil and air temperature; however based on our data and indications in the literature that the largest effects on foliage length have been associated with resource availability we hypothesize that tillage may have induced nutrient and or water limitations at the ash site.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Rubilar, Rafael A. and Albaugh, Timothy J. and Allen, H. Lee and Alvarez, Jose and Fox, Thomas R. and Stape, Jose L.}, year={2013}, month={Sep}, pages={455–463} }
 @article{rubilar_albaugh_allen_alvarez_fox_stape_2013, title={Influences of silvicultural manipulations on above- and belowground biomass accumulations and leaf area in young Pinus radiata plantations, at three contrasting sites in Chile}, volume={86}, ISSN={["1464-3626"]}, DOI={10.1093/forestry/cps055}, abstractNote={1Facultad de Ciencias Forestales Universidad de Concepcion, Cooperativa de Productividad Forestal, Casilla 160-C, Correo 3, Concepcion, Chile 2Department of Forestry and Environmental Resources, North Carolina State University, Jordan Hall 3108, Box 8008, Raleigh, NC 27695-8008, USA 3Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, 228 Cheatham Hall, Blacksburg, VA 24060, USA}, number={1}, journal={FORESTRY}, author={Rubilar, Rafael A. and Albaugh, Timothy J. and Allen, H. Lee and Alvarez, Jose and Fox, Thomas R. and Stape, Jose L.}, year={2013}, month={Jan}, pages={27–38} }
 @article{blinn_albaugh_fox_wynne_stape_rubilar_allen_2012, title={A Method for Estimating Deciduous Competition in Pine Stands Using Landsat}, volume={36}, ISSN={["0148-4419"]}, DOI={10.5849/sjaf.10-034}, abstractNote={A method for identifying pine plantations that may require vegetation control using remotely sensed imagery is presented. Landsat satellite images are used to estimate the leaf area index (LAI) of competing deciduous vegetation by subtracting winter LAI from spring LAI. This differencing works because pine leaf area increases relatively little in comparison with deciduous vegetation between winter and early spring. Competing vegetation LAI levels were compared before and after midrotation release treatments to measure the success of the release treatments. The LAI differencing method estimates the relative abundance of competing vegetation in pine stands and was successful at measuring a reduction in competition levels after release treatments. Midrotation stands prior to release treatments were found to have levels of competing vegetation leaf area equivalent to stands that had never received vegetation control treatments and lower levels of competing vegetation after release treatments.}, number={2}, journal={SOUTHERN JOURNAL OF APPLIED FORESTRY}, author={Blinn, Christine E. and Albaugh, Timothy J. and Fox, Thomas R. and Wynne, Randolph H. and Stape, Jose L. and Rubilar, Rafael A. and Allen, H. Lee}, year={2012}, month={May}, pages={71–78} }
 @article{albaugh_vance_gaudreault_fox_allen_stape_rubilar_2012, title={Carbon Emissions and Sequestration from Fertilization of Pine in the Southeastern United States}, volume={58}, ISSN={["1938-3738"]}, DOI={10.5849/forsci.11-050}, abstractNote={We estimated net carbon emission and sequestration directly attributable to common forest fertil- ization practices for pine plantations in the southeast United States. We used data from the literature to estimate the carbon emissions associated with the production, transportation, and application of fertilizers used for mid-rotation and early rotation applications as well as the stem wood growth response to these applications. These data were scaled to a regional basis with data from the literature and newly acquired fertilizer application information. Product disposition projections were completed through 125 years (five 25-year rotations). On average, application of nitrogen with 28 kg of elemental phosphorus ha 1 to mid-rotation stands sequestered 19.2 Mg ha 1 carbon dioxide (CO2) equivalents as additional stem growth per CO2 equivalent of emissions associated with the fertilizer application. Maximum combined emissions from forest fertilization were 0.34 Tg year 1 CO2 equivalents in 2002, whereas maximum sequestration was 8.70 Tg year 1 CO2 equivalents in 2007. Sequestration lagged emissions because of the long (up to rotation length) stem wood growth response period. After 100 years, approximately 38% of the CO 2 equivalent sequestration attributed to mid-rotation fertilization would still be in use or in a landfill, whereas 26% would have been emitted without capturing energy and 36% would have been used as an energy source. Carbon sequestration associated with forest fertilization was related to the area fertilized annually, which may have fluctuated with fertilizer material and wood product prices. Capturing economic value from the sequestered carbon would likely increase forest fertilization and conse- quently increase carbon sequestration. FOR .S CI. 58(5):419-429.}, number={5}, journal={FOREST SCIENCE}, author={Albaugh, Timothy J. and Vance, Eric D. and Gaudreault, Caroline and Fox, Thomas R. and Allen, H. Lee and Stape, Jose L. and Rubilar, Rafael A.}, year={2012}, month={Oct}, pages={419–429} }
 @article{albaugh_bergh_lundmark_nilsson_stape_allen_linder_2012, title={Do biological expansion factors adequately estimate stand-scale aboveground component biomass for Norway spruce? (vol 258, pg 2628, 2009)}, volume={270}, ISSN={["0378-1127"]}, DOI={10.1016/j.foreco.2012.02.031}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Albaugh, Timothy J. and Bergh, Johan and Lundmark, Tomas and Nilsson, Urban and Stape, Jose Luiz and Allen, H. Lee and Linder, Sune}, year={2012}, month={Apr}, pages={314–314} }
 @article{albaugh_allen_stape_fox_rubilar_price_2012, title={Intra-annual nutrient flux in Pinus taeda}, volume={32}, ISSN={["1758-4469"]}, DOI={10.1093/treephys/tps082}, abstractNote={Intra-annual nutrient (nitrogen, phosphorus, potassium, calcium and magnesium) flux was quantified for Pinus taeda L. at a nutrient-poor, well-drained sandy site in Scotland County, NC, USA where a 2 × 2 factorial of irrigation and nutrition was applied in four replications in a 10-year-old stand with 1200 stems ha(-1). Treatments were applied with the goal of providing optimum nutrition (no nutritional deficiencies) and water availability. Component (foliage, branch, stem and root) nutrient content was estimated monthly for 2 years using nutrient concentration and phenology assessments combined with destructive harvests. Positive flux values indicated nutrient accumulation in the trees while negative values indicated nutrient loss from the trees. Fertilization significantly increased nitrogen, phosphorus, potassium, calcium and magnesium flux 140%, on average, over non-fertilized. Irrigation significantly increased calcium flux 28% while there was no significant irrigation effect on nitrogen, phosphorus, potassium or magnesium. Maximum nutrient fluxes (kg ha(-1) day(-1)) for non-fertilized and fertilized stands were 0.36 and 1.05 for nitrogen, 0.042 and 0.095 for phosphorus, 0.13 and 0.51 for potassium, 0.27 and 0.42 for calcium, and 0.04 and 0.12 for magnesium, respectively. Maximum flux was coincident with ephemeral tissue (foliage and fine root) development and likely would be higher in stands with more foliage than those observed in this study (projected leaf area indices were 1.5 and 3.0 for the non-fertilized and fertilized stands). Minimum nutrient fluxes (kg ha(-1) day(-1)) for non-fertilized and fertilized stands were -0.18 and -0.42 for nitrogen, -0.029 and -0.070 for phosphorus, -0.05 and -0.18 for potassium, -0.04 and -0.05 for calcium, and -0.02 and -0.03 for magnesium, respectively. Minimum fluxes were typically observed in the dormant season and were linked to foliage senescence and branch death. Foliage and branch component nutrient contents were out of phase for nitrogen, phosphorus, potassium and magnesium, indicating nutrient retranslocation and storage in branches prior to foliage development and after foliage senescence. In contrast to current operational fertilizer programs which often target winter application these data suggest the best application times would be during foliage development.}, number={10}, journal={TREE PHYSIOLOGY}, author={Albaugh, Timothy J. and Allen, H. Lee and Stape, Jose L. and Fox, Thomas R. and Rubilar, Rafael A. and Price, James W.}, year={2012}, month={Oct}, pages={1237–1258} }
 @article{albaugh_stape_fox_rubilar_allen_2012, title={Midrotation Vegetation Control and Fertilization Response in Pinus taeda and Pinus elliottii across the Southeastern United States}, volume={36}, ISSN={["0148-4419"]}, DOI={10.5849/sjaf.10-042}, abstractNote={We examined fertilization (224 and 56 kg ha−1 of elemental nitrogen and phosphorus, applied as urea and diammonium phosphate, respectively) and vegetation control (one-time site-specific application) in a 2 × 2 factorial design with three or four replicates at each site on 13 sites (10 in Pinus taeda and 3 in Pinus elliottii). Nitrogen and phosphorus limited pine growth on seven sites where we found significant volume growth responses to fertilization in at least one measurement period. Five sites had significant volume growth responses to vegetation control in at least one measurement period. Biologic response treatment order was fertilizer plus vegetation control > fertilizer > vegetation control. The combined treatment effects were additive, indicating that resources other than nitrogen and phosphorus were being ameliorated by the vegetation control. Vegetation control response was not related to estimates of competing vegetation basal area, and its duration was likely limited by regrowth of competing vegetation on some sites. Competing vegetation leaf area was proposed as a good metric by which to estimate the extent of interference of noncrop vegetation. We recommend that future work examining vegetation control focus on a process approach to better understand the influences of competing vegetation on crop tree growth.}, number={1}, journal={SOUTHERN JOURNAL OF APPLIED FORESTRY}, author={Albaugh, Timothy J. and Stape, Jose L. and Fox, Thomas R. and Rubilar, Rafael A. and Allen, H. Lee}, year={2012}, month={Feb}, pages={44–53} }
 @article{albaugh_allen_stape_fox_rubilar_carlson_pezzutti_2010, title={Leaf area duration in natural range and exotic Pinus taeda}, volume={40}, ISSN={["0045-5067"]}, DOI={10.1139/x09-190}, abstractNote={Exotic Pinus taeda L. plantations may be more productive than native ones. Several hypotheses may explain this difference; however, process models with a light-interception-driving variable cannot test these hypotheses without foliage display first being quantified in native and exotic trees. We quantified leaf area duration in North Carolina, USA (natural), and Gobernador Virasoro, Argentina (exotic), with no additional nutrients and optimum fertilizer treatments. More (60%–100%) foliage was displayed but for a shorter (∼86 fewer days) time per fascicle in the exotics than in the naturals. Study inference was limited, with only one native and one exotic site. However, while the sites were markedly different in soils, climate, resource availability, and genetics, and we observed significant differences in fascicle display and longevity, most fascicles at both sites survived two growing seasons: the one in which they were produced and the subsequent one. This robust finding indicates it would be reasonable...}, number={2}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={Albaugh, Timothy J. and Allen, H. Lee and Stape, Jose Luiz and Fox, Thomas R. and Rubilar, Rafael A. and Carlson, Colleen A. and Pezzutti, Raul}, year={2010}, month={Feb}, pages={224–234} }
 @article{rubilar_allen_alvarez_albaugh_fox_stape_2010, title={Silvicultural manipulation and site effect on above and belowground biomass equations for young Pinus radiata}, volume={34}, ISSN={["1873-2909"]}, DOI={10.1016/j.biombioe.2010.07.015}, abstractNote={There is little understanding of how silvicultural treatments, during the early stages of tree development, affect allometric relationships. We developed and compared stem, branch, foliage, coarse and fine root biomass, and leaf area estimation equations, for four-year-old genetically improved radiata pine trees grown on three contrasting soil-site conditions. At each site, selected trees were destructively sampled from a control (shovel planted, no weed control, fertilized with 2 g of boron), a shovel planted + weed control (2 first years) + complete fertilization (nitrogen + phosphorus + boron 2 first years + potassium 2nd year), and a soil tillage (subsoil at 60 cm) + weed control (first 2 years) + complete fertilization treatment. Tissues were separated into foliage, branch, stem, fine and coarse roots (>2 mm). Regression equations for each tree biomass tissue versus leaf area were fit for each site and compared among treatments and sites with the same genetic material. Our results indicated that individual tree biomasses for young plantations are affected by silvicultural treatment and site growing conditions. Higher variability in estimates was found for foliage and branches due to the ephemeral nature of these components. Stem biomass equations vary less, but differences in biomass equations were found among sites and treatments. Coarse root biomass estimates were variable but less than expected, considering the gradient among sites. Similar to stem biomass, a simple positive general linear relationship between root collar diameter, or diameter at breast height with coarse roots biomass was developed across sites and treatments.}, number={12}, journal={BIOMASS & BIOENERGY}, author={Rubilar, Rafael A. and Allen, H. Lee and Alvarez, Jose S. and Albaugh, Timothy J. and Fox, Thomas R. and Stape, Jose L.}, year={2010}, month={Dec}, pages={1825–1837} }
 @article{carlson_fox_burkhart_allen_albaugh_2009, title={Accuracy of subsampling for height measurements in loblolly pine plots}, volume={33}, number={3}, journal={Southern Journal of Applied Forestry}, author={Carlson, C. A. and Fox, T. R. and Burkhart, H. E. and Allen, H. L. and Albaugh, T. J.}, year={2009}, pages={145–149} }
 @article{albaugh_bergh_lundmark_nilsson_stape_allen_linder_2009, title={Do biological expansion factors adequately estimate stand-scale aboveground component biomass for Norway spruce?}, volume={258}, ISSN={["0378-1127"]}, DOI={10.1016/j.foreco.2009.09.021}, abstractNote={We developed site specific component (stem, branch, and foliage) biomass functions for two sites in Sweden (64° and 57° North latitude) where four treatments (control, irrigated, fertilized, irrigated plus fertilized) were applied in the existing Norway spruce stands (Picea abies L. Karst.) for 17 years. We tested for site effects in the component biomass equations and compared site specific biomass estimates to those generated using published functions (Lehtonen et al., 2004, Wirth et al., 2004). Site effects were significant for all components and indicated it would be unlikely to generate equations that well estimate biomass across the Norway spruce range as implicitly indicated in our efforts to generate species biomass expansion factors. We rejected our hypothesis that the published functions would well estimate component biomass for control plots. The published functions did not compare well with site specific component biomass estimates for the other treatments; both published functions well estimated stem mass up to stem mass of 25 Mg ha−1, beyond which stem mass was overestimated, and both functions over and under estimated foliage and branch mass. Nor did the published functions compare well with each other, with stem, foliage and branch mass estimate differences of 12, 55, −8% and 11, 77, and 59% for the southern and northern sites, respectively, when averaged over all treatments and years. Adding limiting resources through fertilization increased stem, foliage and branch mass 57, 11, 18% and 120, 37, and 69% at the southern and northern sites, respectively, which would increase carbon sequestration and available stemwood and bioenergy materials. We recommend that more effort is spent in process-based modeling to better predict mass at a given site and ultimately provide better estimates of carbon sequestration and bioenergy material production changes.}, number={12}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Albaugh, Timothy J. and Bergh, Johan and Lundmark, Tomas and Nilsson, Urban and Stape, Jose Luiz and Allen, H. Lee and Linder, Sune}, year={2009}, month={Nov}, pages={2628–2637} }
 @article{albaugh_allen_fox_carlson_rubilar_2009, title={Opportunities for fertilization of loblolly pine in the sandhills of the southeastern United States}, volume={33}, number={3}, journal={Southern Journal of Applied Forestry}, author={Albaugh, T. and Allen, H. L. and Fox, T. R. and Carlson, C. A. and Rubilar, R. A.}, year={2009}, pages={129–136} }
 @article{carlson_fox_allen_albaugh_2008, title={Modeling mid-rotation fertilizer responses using the age-shift approach}, volume={256}, ISSN={["0378-1127"]}, DOI={10.1016/j.foreco.2008.04.020}, abstractNote={Growth and yield modelers have incorporated mid-rotation fertilizer responses by: modifying site index; developing new models to include fertilizer responses directly; using multipliers or additional terms to scale existing models. We investigated the use of age-shifts to model mid-rotation fertilizer responses. Age-shift prediction models were constructed from 43 installations of a nitrogen (0, 112, 224 and 336 kg ha−1 elemental) by phosphorus (0, 28 and 56 kg ha−1 elemental) factorial experiment established in mid-rotation loblolly (Pinus taeda L.) pine stands in the southeastern US. Age-shifts for dominant height and basal area increased with time after fertilization, to a maximum and then either remained fairly constant, or declined. The initial rate of increase, maximum age-shift and decline were functions of the rate and combinations of fertilizers applied, as well as stand density and age at fertilization. Volume age-shifts increased linearly throughout the 10-year measurement period for most treatments with the rate of increase being a function of the elements applied, stocking, site index and age at fertilization. A mid-rotation fertilizer application of 224 and 28 kg ha−1 elemental N and P, respectively, resulted in age-shifts of 1.1, 1.9 and 2.4 years for dominant height, basal area and volume, respectively, 10 years after fertilization. The age-shifts were incorporated into growth and yield models.}, number={3}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Carlson, Colleen A. and Fox, Thomas R. and Allen, H. Lee and Albaugh, Timothy J.}, year={2008}, month={Jul}, pages={256–262} }
 @article{albaugh_allen_fox_2008, title={Nutrient use and uptake in Pinus taeda}, volume={28}, ISSN={["0829-318X"]}, DOI={10.1093/treephys/28.7.1083}, abstractNote={We quantified nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) content, use (nutrient amount for one growth year), retranslocation (nutrients recycled before foliage senescence), uptake (use minus retranslocation), volume production per unit of uptake and fertilizer-uptake efficiency (percent applied taken up) in a 2 x 2 (nutrient and water) factorial experiment replicated four times in an 8-year-old loblolly pine (Pinus taeda L.) stand growing on a nutrient-poor sandy soil in Scotland County, North Carolina, USA. Over 14 years, we applied 1140, 168, 393, 168 and 146 kg ha(-1) of elemental N, P, K, Ca and Mg fertilizer, respectively, and an average of 710 mm year(-1) of irrigation. All plots received complete vegetation control. Fertilization about doubled tissue N, P, K and Mg contents at age 21, whereas irrigation resulted in smaller increases in nutrient contents. Maximum annual uptake was 101, 9.3, 44, 37 and 13 kg ha(-1) year(-1) and volume production per unit of nutrient uptake was 0.35, 3.5, 0.66, 1.1 and 3.1 m(3) kg(-1), for N, P, K, Ca and Mg, respectively. Irrigated plots had greater volume production per unit of N, P, K and Mg uptake than control plots, likely because irrigation allowed photosynthesis to continue during dry periods. Fertilized plus irrigated plots had less volume production per unit of these elements than the fertilized plots either because nutrient uptake exceeded the requirement for optimum growth or because available water (rainfall plus irrigation) was insufficient for the leaf area achieved with fertilization. At age 19, fertilizer-uptake efficiencies for N, P, K, Ca and Mg were 53, 24, 62, 57 and 39%, respectively, and increased with irrigation to 68, 36, 78, 116 and 55%, respectively. The scale of fertilizer uptake was likely a result of low native site nutrient availability, study longevity, measurement of all tissue components on site, a comprehensive assessment of coarse roots, and the 3-m rooting depth. Ecosystem nitrogen retention (applied nitrogen found in living plant material, litter fall and soil to 150-cm depth) was estimated at 79% at age 17, a value that would likely be greater when including soil nitrogen to rooting depth and calculating retention at age 21 when the study ended. The ecosystem retention value provides evidence that intensive site resource management can be accomplished with low likelihood of applied materials moving offsite.}, number={7}, journal={TREE PHYSIOLOGY}, author={Albaugh, Timothy J. and Allen, H. Lee and Fox, Thomas R.}, year={2008}, month={Jul}, pages={1083–1098} }
 @article{albaugh_allen_fox_2007, title={Historical patterns of forest fertilization in the southeastern United States from 1969 to 2004}, volume={31}, number={3}, journal={Southern Journal of Applied Forestry}, author={Albaugh, T. J. and Allen, H. L. and Fox, T. R.}, year={2007}, pages={129–137} }
 @article{fox_allen_albaugh_rubilar_carlson_2007, title={Tree nutrition and forest fertilization of pine plantations in the southern United States}, volume={31}, number={1}, journal={Southern Journal of Applied Forestry}, author={Fox, T. R. and Allen, H. L. and Albaugh, T. J. and Rubilar, R. and Carlson, C. A.}, year={2007}, pages={5–11} }
 @article{fox_allen_albaugh_rubilar_carlson_2006, title={Forest fertilization in Southern pine plantations}, volume={90}, number={2}, journal={Better Crops With Plant Food}, author={Fox, T. R. and Allen, H. L. and Albaugh, T. J. and Rubilar, R. and Carlson, C. A.}, year={2006}, pages={12–15} }
 @article{carlson_fox_colbert_kelting_allen_albaugh_2006, title={Growth and survival of Pinus taeda in response to surface and subsurface tillage in the southeastern United States}, volume={234}, ISSN={["0378-1127"]}, DOI={10.1016/j.foreco.2006.07.002}, abstractNote={A trial series investigating the impact of surface and subsurface tillage on the survival and growth of planted Pinus taeda L. was established between 1994 and 1998 with the goal of identifying site types responsive to tillage. The trial series consisted of 15 studies with multiple replicates of a 2 × 2 factorial with surface (offset disking or opposed bedding) and subsurface (winged subsoiling shank) tillage. Subsurface tillage significantly improved survival at four sites and surface tillage improved survival at one site. The positive response to the subsurface tillage was associated with the Piedmont sites where survival improved from 74 to 82%. Surface tillage significantly improved height, diameter and volume growth with the response being greatest on soils with siliceous mineralogy, which showed an improvement of 5.1 m3 ha−1 at 6 years. The improvement was less for soils with kaolinitic mineralogy (4.0 m3 ha−1) or those with mixed mineralogy (3.1 m3 ha−1). Initially Piedmont sites showed a positive response due to subsurface tillage. However, the response was short lived and had dissipated by year 6. Effects of tillage on stand uniformity were negligible. In general, responses to tillage were relatively small compared to those that can be obtained from other silvicultural practices such as vegetation control and fertilization.}, number={1-3}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Carlson, Colleen A. and Fox, Thomas R. and Colbert, Steve R. and Kelting, Daniel L. and Allen, H. Lee and Albaugh, Timothy J.}, year={2006}, month={Oct}, pages={209–217} }
 @article{albaugh_allen_fox_2006, title={Individual tree crown and stand development in Pinus taeda under different fertilization and irrigation regimes}, volume={234}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2006.05.074}, abstractNote={We examined individual tree foliage mass and branch demography for 13 years in a Pinus taeda L. stand growing on a nutrient poor, well drained sandy soil with a 2 × 2 factorial of fertilization and irrigation treatments replicated four times. Branch level foliage mass was estimated using equations derived from 2500 destructively sampled branches with branch basal diameter, crown location, age and treatment as independent variables. Branch diameter and crown location were measured for all live branches on 80 trees (20 in each treatment) each year for 13 years. Maximum dormant season individual tree foliage mass was 5.4 and 10.7 kg tree−1 in the control and fertilized and irrigated treatments, respectively. The maximum fertilized and irrigated individual tree foliage mass was achieved 3 years after treatment initiation when apparent light and space limitations prevented additional increase in individual tree foliage mass. Individual stem volume increment was linearly related to individual tree foliage mass and individual tree foliage mass was reduced by the presence of large nearby trees. Branch diameter and number were significantly increased by fertilization (52 branches tree−1, 11% increase, 19.8 mm branch−1, 14% increase). Branch longevity was significantly reduced by fertilization; branches survived 6.6 and 5.4 years for the non-fertilized and fertilized treatments, respectively. Branch size, number and longevity in the fertilized treatments would not be likely to reduce stem quality. In stands where nutrients and water were adequate and light and space limitations developed, individual tree foliage mass development could be increased with thinning. However, individual tree foliage mass development was limited much earlier in stand development than heretofore thought. Waiting to thin until stand conditions currently used to trigger thinning (to avoid density dependent mortality) would promote overall stand growth at the expense of crop tree growth. Individual tree foliage mass was correlated with branch development and branches in the lower crown half were more likely to die, had a lower carbon balance due to low light and high respiring tissue relative to photosynthesizing tissue. This combination of factors indicated that pruning may be a likely tool to manage crown development and insure that crop trees have a high value stem. The balance between individual stem growth and stand growth may need to be reevaluated in the context of currently used intensive silvicultural regimes.}, number={1-3}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Albaugh, Timothy J. and Allen, H. Lee and Fox, Thomas R.}, year={2006}, month={Oct}, pages={10–23} }
 @article{albaugh_allen_kress_2006, title={Root and stem partitioning of Pinus taeda}, volume={20}, ISSN={["0931-1890"]}, DOI={10.1007/s00468-005-0024-4}, number={2}, journal={TREES-STRUCTURE AND FUNCTION}, author={Albaugh, TJ and Allen, HL and Kress, LW}, year={2006}, month={Mar}, pages={176–185} }
 @article{albaugh_allen_dougherty_johnsen_2004, title={Long term growth responses of loblolly pine to optimal nutrient and water resource availability}, volume={192}, ISSN={["1872-7042"]}, DOI={10.1016/j.foreco.2004.01.002}, abstractNote={A factorial combination of four treatments (control (CW), optimal growing season water availability (IW), optimum nutrient availability (FW), and combined optimum water and nutrient availability (FIW)) in four replications were initiated in an 8-year-old Pinus taeda stand growing on a droughty, nutrient-poor, sandy site in Scotland County, NC and maintained for 9 years. Results for the first 4 years after treatment initiation at this study were first reported by Albaugh et al. [For. Sci. 44 (1998) 317]. The site is primarily nutrient limited and all measured stand parameters (height, basal area, leaf area index, live crown length, stem mass accumulation, current annual stem mass increment) were increased with fertilization throughout the study period. Irrigation effects were also positive for these parameters but the increases were much smaller than those found with fertilization. For example, 9 years after treatment initiation, standing stem mass was increased 100 and 25% by fertilization and irrigation, respectively, while current annual increment of stem biomass production was increased 119 and 23% by fertilization and irrigation, respectively. Interestingly, stem density (stems ha−1) was not significantly affected by treatment in any year of the study. Growth efficiency (stem mass increment per unit leaf area index) was 1.9 Mg ha−1 per year per LAI for CW and influenced by treatment with IW, FW, and FIW achieving growth efficiencies of 2.4, 2.7 and 2.9 Mg ha−1 per year per LAI, respectively. Growth efficiency appeared to be relatively stable in the last 4 years of the study. Ring specific gravity was measured in the third, fourth, and fifth years after treatment initiation. An average reduction in ring specific gravity of 7.5% was observed with fertilization while irrigation had little effect on specific gravity in any year measured. The continuation of high growth rates with no observable growth decline in the treated stands throughout the 9-year study may be a function of the age of the stands when treatments were initiated (8 years), the very poor initial nutrient and moisture availability, and/or the application of an ongoing optimum nutrient regime at the site. The fertilized plots are now at or near an age and a size when a commercial harvest would be feasible. For the stand conditions at this site, then, the optimum nutrient availability plots have achieved high productivity throughout the economic life of the stand without measurable declines in stand productivity.}, number={1}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Albaugh, TJ and Allen, HL and Dougherty, PM and Johnsen, KH}, year={2004}, month={Apr}, pages={3–19} }
 @article{sampson_albaugh_johnson_allen_zarnoch_2004, title={Monthly leaf area index estimates from point-in-time measurements and needle phenology for Pinus taeda (vol 33, pg 2477, 2003)}, volume={34}, number={3}, journal={Canadian Journal of Forest Research}, author={Sampson, D. A. and Albaugh, T. J. and Johnson, K. H. and Allen, H. L. and Zarnoch, S. J.}, year={2004} }
 @article{albaugh_rubilar_alvarez_allen_2004, title={Radiata pine response to tillage fertilization and weed control in Chile}, volume={25}, DOI={10.4067/s0717-92002004000200002}, abstractNote={Se iniciaron en el ano 2000 ensayos para investigar la respuesta a la preparacion de suelos (pala vs. subsolado), control de malezas (sin control vs. dos anos en bandas) y fertilizacion (1,5 g de B por planta vs. 150 g de fosfato diamonico + 1,5 g de B por planta) al establecimiento de pino radiata (Pinus radiata D. Don) en Chile. Los ensayos se establecieron en sitios con suelos de cenizas volcanicas recientes, cenizas volcanicas antiguas ("rojo arcillosos volcanicos"), arenas volcanicas y sedimentos fluviales depositados sobre material granitico. El diseno experimental correspondio a parcelas divididas, donde areas con preparacion de suelos (parcelas principales) fueron divididas en parcelas con control de malezas y fertilizacion (subparcelas), considerando un area minima de tratamiento de 0,4 ha incluyendo buffers de 10 m entre parcelas. Mediciones de altura, diametro de cuello y diametro a la altura del pecho (DAP) fueron obtenidas durante tres anos, junto con muestreos foliares durante los dos primeros anos. Al tercer ano de crecimiento, todos los sitios presentaron respuestas positivas al control de malezas con un promedio de 3,1 cm en diametro y 1 m en altura. Respuestas positivas a la fertilizacion en altura (0,1 m) fueron obtenidas solo en sitios de arenas volcanicas; analisis foliares nutricionales revelaron una escasa absorcion de los nutrientes en la plantacion posiblemente dada una aplicacion tardia de los fertilizantes. El subsolado mostro respuestas positivas en suelos de arenas volcanicas y de sedimentos fluviales, sin embargo, la respuesta fue 95% y 42% menor a la obtenida para control de malezas en estos sitios respectivamente. El control de malezas y el subsolado redujeron la variabilidad en altura en todos los sitios. Nuestra hipotesis es que la temprana respuesta al control de malezas se mantendra hasta la edad de rotacion (curva tipo B) para sitios de cenizas volcanicas antiguas y en sedimentos fluviales sobre material granitico; no obstante, en sitios de cenizas volcanicas recientes y arenas volcanicas esta respuesta decrecera o desaparecera (curva tipo C) a la edad de rotacion. Indudablemente, en todos los sitios evaluados, el control de malezas es recomendable. La fertilizacion es recomendable junto con el control de malezas en sitios de arenas volcanicas. Por tanto, estudios adicionales son necesarios para determinar la epoca oportuna de fertilizacion que asegure una adecuada absorcion de los nutrientes por parte de la plantacion. El subsolado no es necesario en los sitios evaluados, sin embargo, efectos indirectos tales como: mejor accesibilidad, rendimiento y calidad de plantacion, deben ser cuantificados al evaluar los beneficios de esta actividad.}, number={2}, journal={Bosque}, author={Albaugh, T. J. and Rubilar, R. and Alvarez, J. and Allen, Howard}, year={2004}, pages={5–15} }
 @misc{maier_albaugh_allen_dougherty_2004, title={Respiratory carbon use and carbon storage in mid-rotation loblolly pine (Pinus taeda L.) plantations: the effect of site resources on the stand carbon balance}, volume={10}, ISSN={["1365-2486"]}, DOI={10.1111/j.1529-8817.2003.00809.x}, abstractNote={We used estimates of autotrophic respiration (RA), net primary productivity (NPP) and soil CO2 evolution (Sff), to develop component carbon budgets for 12‐year‐old loblolly pine plantations during the fifth year of a fertilization and irrigation experiment. Annual carbon use in RA was 7.5, 9.0, 15.0, and 15.1 Mg C ha−1 in control (C), irrigated (I), fertilized (F) and irrigated and fertilized (IF) treatments, respectively. Foliage, fine root and perennial woody tissue (stem, branch, coarse and taproot) respiration accounted for, respectively, 37%, 24%, and 39% of RA in C and I treatments and 38%, 12% and 50% of RA in F and IF treatments. Annual gross primary production (GPP=NPP+RA) ranged from 13.1 to 26.6 Mg C ha−1. The I, F, and IF treatments resulted in a 21, 94, and 103% increase in GPP, respectively, compared to the C treatment. Despite large treatment differences in NPP, RA, and carbon allocation, carbon use efficiency (CUE=NPP/GPP) averaged 0.42 and was unaffected by manipulating site resources.}, number={8}, journal={GLOBAL CHANGE BIOLOGY}, author={Maier, CA and Albaugh, TJ and Allen, HL and Dougherty, PM}, year={2004}, month={Aug}, pages={1335–1350} }
 @article{sampson_albaugh_johnsen_allen_zarnoch_2003, title={Monthly leaf area index estimates from point-in-time measurements and needle phenology for Pinus taeda}, volume={33}, ISSN={["0045-5067"]}, DOI={10.1139/X03-166}, abstractNote={Leaf area index (LAI) of loblolly pine (Pinus taeda L.) trees of the southern United States varies almost twofold interannually; loblolly pine, essentially, carries two foliage cohorts at peak LAI (September) and one at mini- mum (March-April). Herein, we present an approach that may be site invariant to estimate monthly LAI for loblolly pine using point-in-time measurements from a LI-COR LAI-2000 plant canopy analyzer (PCA). Our analyses used nee- dle accretion and abscission data from monthly needle counts and destructive harvest data from a replicate d2×2f ac- torial experiment of water and nutrition amendments. No significant treatment effects on relative needle accretion or abscission were observed. Cohort (interannual) differences in needle accretion were found but appeared trivial. Cohort year had variable effects on needle abscission. Abscission of current-year foliage began in July and continued through November of the third year; however, only 7%-9% remained 23 months following bud initiation. A treatment-invariable regression of PCA measurements on cohort foliage biomass (r 2 ≈ 0.98) was used to estimate annual cohort LAI. We derived monthly estimates of LAI from cohort accretion and abscission and cohort LAI. Monthly estimates of LAI for loblolly pine, using point-in-time measurements from the PCA, appear possible, although further testing is required. Resume : L'indice de surface foliaire (LAI) du pin a encens (Pinus taeda L.) du sud des Etats-Unis varie du simple au double au cours d'une annee; essentiellement, le pin a encens porte deux cohortes de feuillage au moment du pic de LAI (septembre) et une seule lors de son minimum (mars-avril). Nous presentons ici une approche independante du site pour estimer le LAI mensuel du pin a encens a l'aide de mesures ponctuelles avec le LI-COR LAI-2000 « plant canopy analyzer » (PCA). Nos analyses ont utilise des donnees de croissance et d'abscission issues de comptages men- suels d'aiguilles et des donnees provenant de recoltes destructives faites dans une experience factorielle comportant deux facteurs (irrigation et fertilisation) avec deux niveaux chacun. Aucun effet significatif des traitements n'a ete ob- serve sur la croissance relative ou l'abscission des aiguilles. Des differences entre les cohortes (interannuelles) ont ete observees pour la croissance des aiguilles mais sont insignifiantes. L'annee des cohortes avait des effets variables sur l'abscission des aiguilles. L'abscission du feuillage de l'annee commence en juillet et se poursuit au-dela de novembre de la troisieme annee, avec par contre seulemen t7a9%d es aiguilles quirestent 23 mois apres l'initiation des bour- geons. Une regression ne tenant pas compte des traitements et liant les mesures faites avec le PCA et la biomasse foliaire des cohortes (r 2 ≈ 0,98) a ete utilisee pour estimer le LAI des cohortes annuelles. Nous avons derive des esti- mations mensuelles de LAI a partir de la croissance et de l'abscission des cohortes et de LAI des cohortes. Les estima- tions mensuelles de LAI pour le pin a encens a l'aide de mesures ponctuelles effectuees avec le PCA semblent possibles meme si des tests supplementaires sont requis.}, number={12}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={Sampson, DA and Albaugh, TJ and Johnsen, KH and Allen, HL and Zarnoch, SJ}, year={2003}, month={Dec}, pages={2477–2490} }
 @article{albaugh_allen_zutter_quicke_2003, title={Vegetation control and fertilization in midrotation Pinus taeda stands in the southeastern United States}, volume={60}, ISSN={["1286-4560"]}, DOI={10.1051/forest:2003054}, abstractNote={Nous avons evalue l'effet sur des plantations de Pinus taeda L. de differentes methodes de controle de la vegetation (VC) a savoir des traitements chimiques (glyphosate, imazapyr, metsulfuron, methyl et triclopyr), des interventions mecaniques et une fertilisation phosphatee, ceci sur un ensemble de stations situees en plaine et en piedmont des Etats du Sud Ouest, portant des peuplements allant de 10 a 22 ans en debut d'experience. Nous avons etudie la surface terriere des pins et des feuillus (principale vegetation concurrente) ainsi que le volume et la composition foliaire en nutrients des pins dans un dispositif en bloc complet a 2 ou 3 repetitions, avec une combinaison factorielle 2 x 2 d'une seule application de VC et de fertilisation. Le controle de la vegetation reduit l'importance des feuillus de 70 % au moins, sur toutes les stations. En moyenne, c'est le traitement combine qui a l'effet le plus important sur le volume de pin (6,1 et 11,0 m 3 ha -1 an -1 ) suivi par la fertilisation seule (5,5 et 7,9 m 3 ha -1 an -1 ) et par le VC seul (1,1 et 4,5 m 3 ha -1 an -1 ), les deux nombres entre parentheses correspondant aux annees 1 et, puis 3 et 4. L'amplitude de l'effet sur le volume des pins pour l'ensemble des traitements et des stations va de -3 a 12 m 3 ha -1 an -1 . Il est possible que certains stations, non representees ici, caracterisees par un plus grand deficit en eau, une concurrence plus importante et des disponibilites suffisantes en azote et phosphore, puissent reagir de maniere plus importante aux traitements de controle de la vegetation. La fertilisation seule n'a pas d'effet significatif sur la surface terriere des feuillus aux annees 2 et 4 ; la proportion de feuillus en surface terriere est a peu pres la meme avant et apres traitement (12 et 11 %) dans les parcelles temoins et fertilisees. Pour expliquer la superiorite du traitement combine sur la croissance des pins au bout de 4 ans, nous emettons l'hypothese suivante : l'effet fertilisation tend a diminuer, les nutrients apportes ayant ete utilises, mais l'effet VC augmente compte tenu de l'augmentation des disponibilites en nutrients et en eau au profit des pins, la vegetation concurrente ne pouvant pas se developper.}, number={7}, journal={ANNALS OF FOREST SCIENCE}, author={Albaugh, TJ and Allen, HL and Zutter, BR and Quicke, HE}, year={2003}, pages={619–624} }
 @article{king_albaugh_allen_buford_strain_dougherty_2002, title={Below-ground carbon in put to soil is control led by nutrient availability and fine root dynamics in loblolly pine}, volume={154}, ISSN={["0028-646X"]}, DOI={10.1046/j.1469-8137.2002.00393.x}, abstractNote={•  Availability of growth limiting resources may alter root dynamics in forest ecosystems, possibly affecting the land-atmosphere exchange of carbon. This was evaluated for a commercially important southern timber species by installing a factorial experiment of fertilization and irrigation treatments in an 8-yr-old loblolly pine (Pinus taeda) plantation. •  After 3 yr of growth, production and turnover of fine, coarse and mycorrhizal root length was observed using minirhizotrons, and compared with stem growth and foliage development. •  Fertilization increased net production of fine roots and mycorrhizal roots, but did not affect coarse roots. Fine roots had average lifespans of 166 d, coarse roots 294 d and mycorrhizal roots 507 d. Foliage growth rate peaked in late spring and declined over the remainder of the growing season, whereas fine roots experienced multiple growth flushes in the spring, summer and fall. •  We conclude that increased nutrient availability might increase carbon input to soils through enhanced fine root turnover. However, this will depend on the extent to which mycorrhizal root formation is affected, as these mycorrhizal roots have much longer average lifespans than fine and coarse roots.}, number={2}, journal={NEW PHYTOLOGIST}, author={King, JS and Albaugh, TJ and Allen, HL and Buford, M and Strain, BR and Dougherty, P}, year={2002}, month={May}, pages={389–398} }
 @article{nilsson_albaugh_allen_2002, title={Development of size hierarchies prior to the onset of density-dependent mortality in irrigated and fertilized loblolly pine stands}, volume={32}, ISSN={["0045-5067"]}, DOI={10.1139/X02-021}, abstractNote={Nine years of growth and stand development were investigated in a 2 × 2 nutrient and water factorial experiment with four replications. The study was located on an infertile, excessively drained sandy site in Scotland County, North Carolina, U.S.A. The hypothesis tested was that increased growth following irrigation and fertilization would increase the rate at which size hierarchies develop. The hypothesis was investigated by comparing the coefficient of variation (CV) of stem volume over time and examining the stem volume relative growth rate (RGR) of trees of different initial size in control and irrigated + fertilized stands. Even though there were no statistically significant differences in CV among treatments, there was a tendency for increased CV over time in the control stands, whereas CV initially increased, then decreased, and became constant in the irrigated + fertilized plots. The lack of increase in CV in the irrigated + fertilized plots was explained by unusually low variation in RGR across t...}, number={6}, journal={CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE}, author={Nilsson, U and Albaugh, TJ and Allen, HL}, year={2002}, month={Jun}, pages={989–996} }
 @article{ludovici_allen_albaugh_dougherty_2002, title={The influence of nutrient and water availability on carbohydrate storage in loblolly pine}, volume={159}, ISSN={["0378-1127"]}, DOI={10.1016/S0378-1127(01)00439-X}, abstractNote={We quantified the effects of nutrient and water availability on monthly whole-tree carbohydrate budgets and determined allocation patterns of storage carbohydrates in loblolly pine (Pinus taeda) to test site resource impacts on internal carbon (C) storage. A factorial combination of two nutrient and two irrigation treatments were imposed on a 7-year-old loblolly pine stand in the Sandhills of North Carolina. Monthly collections of foliage, branch, stem, bark, and root tissues were made and total non-structural carbohydrate analyses were performed on samples collected in years 3 and 4 after treatment initiation. Seasonal fluxes of carbohydrates reflected the hypothesized use and storage patterns. Starch concentrations peaked in the spring in all tissues measured; however, minimum concentrations in aboveground tissue occurred in late winter while minimum concentrations in below ground tissue occurred in late fall. Increased nutrient availability generally decreased starch concentrations in current year tissue, while increasing starch in 1-year-old woody tissue. Irrigation treatments did not significantly impact carbohydrate flux. The greatest capacity for starch storage was in below ground tissue, accounting for as much as 400 kg C/ha per year, and more than 65% of the total stored starch C pool. The absolute amount of C stored as starch was significantly increased with increased nutrient availability, however, its relative contribution to the total annual C budget was not changed.}, number={3}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Ludovici, KH and Allen, HL and Albaugh, TJ and Dougherty, PM}, year={2002}, month={Apr}, pages={261–270} }
 @article{landsberg_johnsen_albaugh_allen_mckeand_2001, title={Applying 3-PG, a simple process-based model designed to produce practical results, to data from loblolly pine experiments}, volume={47}, number={1}, journal={Forest Science}, author={Landsberg, J. J. and Johnsen, K. H. and Albaugh, T. J. and Allen, H. L. and McKeand, S. E.}, year={2001}, pages={43–51} }
 @article{sampson_johnsen_ludovici_albaugh_maier_2001, title={Stand-scale correspondence in empirical and simulated labile carbohydrates in loblolly pine}, volume={47}, number={1}, journal={Forest Science}, author={Sampson, D. A. and Johnsen, K. H. and Ludovici, K. H. and Albaugh, T. J. and Maier, C. A.}, year={2001}, pages={60–68} }
 @article{ewers_oren_albaugh_dougherty_1999, title={Carry-over effects of water and nutrient supply on water use of Pinus taeda}, volume={9}, DOI={10.1890/1051-0761(1999)009[0513:COEOWA]2.0.CO;2}, abstractNote={A study of the effects of nutrients and water supply (2 × 2 factorial experiment) was conducted in a 12-yr-old stand of loblolly pine (Pinus taeda L.) during a period in which soil moisture was not augmented by irrigation because of frequent rain events. Information on the responses of sapwood-to-leaf area ratio and early-to-late wood ratio, to four years of treatments led to the hypothesis that the combination of increased nutrient and water supply (IF treatment) will increase tree transpiration rate per unit leaf area (EC,1) above EC,1 in the control (C), as well as increasing EC,1 above that when either the supply of water (I) or of nutrients (F) is increased. We further hypothesized that canopy transpiration (EC) will rank IF > F > I = C, based on the ranking of leaf area index (L) and assuming that the ranking of EC,1 is as first hypothesized. We rejected our first hypothesis, because F had lower EC,1 than the other treatments, rather than IF having higher values. We could not reject the second hypothesis; the ranking of average daily EC was 1.8 mm for IF, 1.2 mm for F, and 0.7 mm for both C and I (se < 0.1 mm for all treatments). Thus, it was the lower EC,1 of the F treatment, relative to IF, that resulted in ranking of EC similar to that hypothesized. Lower EC,1 in F trees was found to relate to lower canopy stomatal conductance, even though soil moisture conditions during the time of the study were similar in all treatments. Only trees in the F treatment absorbed a substantial amount of water (25%) below 1 m in the soil. These results indicate a “carry-over” effect of irrigation when combined with fertilization that increases EC in irrigated trees, relative to unirrigated trees, even under conditions when soil moisture is high and similar in all treatments.}, number={2}, journal={Ecological Applications}, author={Ewers, B. E. and Oren, R. and Albaugh, T. J. and Dougherty, P. M.}, year={1999}, pages={513–525} }
 @article{allen_albaugh_1999, title={Ecophysiological basis for plantation production: a loblolly pine case study}, volume={20}, journal={Bosque}, author={Allen, H. L. and Albaugh, T. J.}, year={1999}, pages={3–8} }
 @article{king_albaugh_allen_kress_1999, title={Stand-level allometry in Pinus taeda as affected by irrigation and fertilization}, volume={19}, DOI={10.1093/treephys/19.12.769}, abstractNote={Changing environmental conditions have the potential to alter allometric relationships between plant parts, possibly leading to ecosystem-level feedbacks. We quantified allometric shifts in field-grown loblolly pine (Pinus taeda L.) in response to altered resource availability based on data from multiple harvests to correct for size-related changes in biomass partitioning. A replicated factorial arrangement of irrigation and fertilization treatments was applied for 4 years to an 8-year-old loblolly pine plantation on a well-drained, low fertility site in North Carolina. Destructive and nondestructive growth measurements were used to develop treatment-specific regressions to estimate stand-level biomass for ephemeral and perennial plant parts, both above- and belowground. Stand-level allometric analysis indicated that irrigation increased biomass partitioning to fine roots and decreased partitioning to foliage, relative to other plant parts. Fertilization increased partitioning to perennial tissues (coarse roots, taproots, and branches) and decreased partitioning to ephemeral tissues (foliage and fine roots). Changes in allometry were small (< 6 %) but statistically significant, indicating that biomass partitioning in loblolly pine changes with altered resource availability, but is probably under strong ontogenetic control.}, number={12}, journal={Tree Physiology}, author={King, J. S. and Albaugh, T. J. and Allen, Howard and Kress, L. W.}, year={1999}, pages={769–778} }
 @inbook{dougherty_allen_kress_murthy_maier_albaugh_sampson_1998, title={An investigation of the impacts of elevated CO2, irrigation, and fertilization on the physiology and growth of loblolly pine}, ISBN={0387948511}, DOI={10.1007/978-1-4612-2178-4_9}, abstractNote={Southern pine forests that are dominated by loblolly pine (Pinus taeda L.) are the most intensively managed forests in the United States. They provide more than 50% of the total softwood being harvested annually in the United States and represent the first or second most economically important agricultural crops in nine of the twelve southeastern states (U.S. Department Agriculture Forest Service, 1988). Thus, any changes in environmental conditions that will alter productivity of these forests will have important ecological, economical, and sociological consequences. Over the past several decades, the environment of southeastern forests has been changing. Increases in acidic deposition (SO4 and NOx), nitrogen inputs (Husar, 1986), atmospheric CO2 concentration (Conway et al., 1988; Keeling et al., 1989), and tropospheric ozone have all been documented to parallel the increase in population since the beginning of the industrial revolution. Climate change has also been predicted for the southeastern United States for the future. Each of these atmospheric and climatic elements that are being altered by human activities has the potential to affect productivity of southern pine forests. Nutrient availability, water availability, atmospheric CO2 concentration, and temperature are presently the principal factors that are limiting the productivity of southern pine forests. Thus, it is extremely important that we understand how changes in these factors will interact to affect physiological processes of forest stands.}, booktitle={The productivity and sustainability of Southern forest ecosystems in a changing environment.  (Ecological studies; 128)}, publisher={New York: Springer}, author={Dougherty, P. M. and Allen, Howard and Kress, L. W. and Murthy, R. and Maier, C. and Albaugh, T. J. and Sampson, D. A.}, editor={Mickler, R. A. and Fox, S.Editors}, year={1998}, pages={149–168} }
 @article{albaugh_allen_dougherty_kress_king_1998, title={Leaf area and above- and belowground growth responses of loblolly pine to nutrient and water additions}, volume={44}, number={2}, journal={Forest Science}, author={Albaugh, T. J. and Allen, H. L. and Dougherty, P. M. and Kress, L. W. and King, J. S.}, year={1998}, pages={317–328} }
 @article{albaugh_mowry_kress_1992, title={ENVIRONMENTAL MONITORING - A FIELD CHAMBER FOR TESTING AIR-POLLUTION EFFECTS ON MATURE TREES}, volume={21}, ISSN={["1537-2537"]}, DOI={10.2134/jeq1992.00472425002100030028x}, abstractNote={A 3.6 m tall by 3 m diam. open-top chamber system built on 12-m towers for the dispensing and exclusion of air pollutants in the foliage of mature loblolly pine (Pinus taeda L.) trees was tested. Statistically significant position and height differences in O₃ concentration inside the chamber were found for different wind speed categories. Calculation of a relative O₃ concentration (ROC) showed remarkably similar relative O₃ profiles for charcoal filtered (CF) and 2x ambient (2x) chambers. Large reductions in ROC are found above the 2.4-m level in both chambers. Ambient air intrusion was reduced in the modified chamber because it was protected by the canopy and contained a tree crown lessening air movement in the chamber. The mean temperature increase in the chamber from 1200 to 1259 h EST was 2.2°C, whereas the maximum temperature increase was 4.8°C. Statistically significant positional temperature differences were found within the chamber. The chamber system design was found useful in testing the effects of gaseous air pollutants on the crown of mature trees and is recommended for designed experiments. This research was supported in part by the Southeastern Forest Exp. Stn., Southern Commercial Forest Res. Coop. of the Forest Response Program. The Forest Response Program, part of the National Acid Precipitation Assessment Program, is jointly sponsored by the USDA-FS, USEPA, and the National Council of the Paper Industry for Air and Stream Improvement (NCASI). This paper has not been subject to USEPA or USDA-FS policy review and should not be construed to represent the policies of either Agency or of NCASI. The use of trade names in this paper does not imply endorsement by the associated agencies of the products named, nor criticism of similar ones not mentioned.}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={ALBAUGH, TJ and MOWRY, FL and KRESS, LW}, year={1992}, pages={476–485} }
 @article{albaugh_allen_kress_1991, title={BIOMASS-D2H RELATIONSHIPS FOR YOUNG LOBLOLLY-PINE AS AFFECTED BY OZONE}, volume={1}, ISSN={["0961-9534"]}, DOI={10.1016/0961-9534(91)90023-6}, abstractNote={The influence of below and above ambient levels of ozone on the relationships between biomass components (foliage, branch, and stem) and DZH was examined using data from 1284 young loblolly pine (Pinus taeda L.) harvested from two ozone field studies. A In-in model form provided a very good fit of the biomass data. Residual plots showed no bias and R2 ranged from 0.94 to 0.99. Ozone treatment significantly affected the shape of biomass—D2H relationships for all components except stem. For a given D2H, increasing ozone dose resulted in less foliage and more branch biomass. After adjusting for age and tree size, increasing ozone dose significantly increased number of branches after one year of ozone treatment. After the second year, ozone dose did not significantly change the number of branches when adjusting for tree size; however, the trends were the same as the first year. Because of the strong negative ozone effect on foliage biomass, total biomass for a given D2H was less for increasing ozone dose. Ozone effects need to be considered when developing biomass equations for young loblolly pine trees.}, number={3}, journal={BIOMASS & BIOENERGY}, author={ALBAUGH, TJ and ALLEN, HL and KRESS, LW}, year={1991}, pages={143–148} }