@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{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{sumnall_trlica_carter_cook_schulte_campoe_rubilar_wynne_thomas_2021, title={Estimating the overstory and understory vertical extents and their leaf area index in intensively managed loblolly pine (Pinus taeda L.) plantations using airborne laser scanning}, volume={254}, ISSN={["1879-0704"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85097899818&partnerID=MN8TOARS}, DOI={10.1016/j.rse.2020.112250}, abstractNote={Data from four discrete-return airborne laser scanning (ALS) acquisitions and three different sensor types across seven experimentally varied loblolly pine (Pinus taeda L.) plantations were used to test published and novel methodologies in quantifying forest structural attributes within stands, including height to live crown (HTLC; i.e. the lowest vertical canopy extent) of the canopy and the contributions to total plot-level leaf area from understory and overstory canopy vegetation. These ALS data were compared to in situ field measurements to develop ALS-based predictive models of these attributes. The correlation between field- and ALS-modeled HTLC data was strong, with an R2 of 0.79 (p < 0.001). We assessed the ability of eight lidar light penetration indices to estimate effective leaf area index (eLAI) in the field. The best predictor of total (sum of understory and overstory) eLAI produced an R2 of 0.88 (p < 0.001). The independent contributions of overstory and understory components could also be accurately predicted by ALS-derived canopy-only eLAI metrics (R2 = 0.71; p < 0.001) and understory-only metrics (R2 = 0.49; p < 0.001). Two new indices, calculated as the sum of return intensity for each foliar layer and correcting for transmission losses, were developed specifically for the vertical strata related to the understory (BLunder) or overstory (BLover). The estimates from BLover were equivalent to the best-performing indices for predicting canopy-only eLAI and the corresponding BLunder was superior to other indices for understory eLAI. The broad spatial and temporal extents of the data, as well as the inclusion of pine plantations with differing stand ages, planting densities, understory control, and thinning treatments, suggest the relationships generated from these methods are robust to site and seasonal variability. The results produced from the analysis of multiple acquisitions implies that the methods presented here are transferable across location, time and sensor design, without implementation-specific calibration, at least for structurally similar loblolly pine plantations.}, journal={REMOTE SENSING OF ENVIRONMENT}, author={Sumnall, Matthew J. and Trlica, Andrew and Carter, David R. and Cook, Rachel L. and Schulte, Morgan L. and Campoe, Otavio C. and Rubilar, Rafael A. and Wynne, Randolph H. and Thomas, Valerie A.}, year={2021}, month={Mar} }
 @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={Abstract}, 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{brito_rubilar_cook_campoe_carter_mardones_2021, title={Evaluating remote sensing indices as potential productivity and stand quality indicators for Pinus radiata plantations}, volume={49}, ISSN={["1413-9324"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85104990073&partnerID=MN8TOARS}, DOI={10.18671/scifor.v49n129.08}, abstractNote={The objective of the present research was to evaluate the use of several spectral vegetation indices (SVIs), including NDVI, SAVI, SR and RSR, obtained from Landsat 7 images, as potential predictors of forest productivity of radiata pine stands. We aimed to evaluate relationships between the variations in stand volume and SVIs over time and the effect of early weed control on stand growth response. We evaluated a large-scale silviculture experiment located at the Central Valley of Chile, since its establishment until 12 years of age, where weed control showed to be the major silvicultural response. Forest inventory measurements were made annually and local equations were used to estimate stand volume. Significant and highly significant correlation was found among SVI ́s and stand productivity parameters. The best relationship was found between NDVI and stand cumulative volume (R-adj=0.92, p-value < 0.0001, RMSE= 0.03), but SR and RSR were able to better track productivity and the major weed control effect on stand volume growth over time. SVIs’ coefficient of variation estimates were correlated with estimates of stand productivity variability but no significant relationships were established to provide an index of stand quality due to the sensor spatial resolution and plot sizes. SVIs may serve as important tools to monitor forest growth and high-resolution imagery may provide valuable estimates of stand variability for inventory assessment or as a support tool for growth and yield models.}, number={129}, journal={SCIENTIA FORESTALIS}, author={Brito, Vitor Vannozzi and Rubilar, Rafael Alejandro and Cook, Rachel Louise and Campoe, Otavio Camargo and Carter, David Robert and Mardones, Oscar}, year={2021}, month={Mar} }
 @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={Abstract}, 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{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{cubbage_kanieski_rubilar_bussoni_olmos_balmelli_donagh_lord_hernández_zhang_et al._2020, title={Global timber investments, 2005 to 2017}, volume={112}, ISSN={1389-9341}, url={http://dx.doi.org/10.1016/j.forpol.2019.102082}, DOI={10.1016/j.forpol.2019.102082}, abstractNote={We estimated timber investment returns for 22 countries and 54 species/management regimes in 2017, for a range of global timber plantation species and countries at the stand level, using capital budgeting criteria, without land costs, at a real discount rate of 8%. Returns were estimated for the principal plantation countries in the Americas—Brazil, Argentina, Uruguay, Chile, Colombia, Venezuela, Paraguay, Mexico, and the United States—as well as New Zealand, Australia, South Africa, China, Vietnam, Laos, Spain, Finland, Poland, Scotland, and France. South American plantation growth rates and their concomitant returns were generally greater, at more than 12% Internal Rates of Return (IRRs), as were those in China, Vietnam, and Laos. These IRRs were followed by those for plantations in southern hemisphere countries of Australia and New Zealand and in Mexico, with IRRs around 8%. Temperate forest plantations in the U.S. and Europe returned less, from 4% to 8%, but those countries have less financial risk, better timber markets, and more infrastructure. Returns to most planted species in all countries except Asia have decreased from 2005 to 2017. If land costs were included in calculating the overall timberland investment returns, the IRRs would decrease from 3 percentage points less for loblolly pine in the U.S. South to 8 percentage points less for eucalypts in Brazil.}, journal={Forest Policy and Economics}, publisher={Elsevier BV}, author={Cubbage, Frederick and Kanieski, Bruno and Rubilar, Rafael and Bussoni, Adriana and Olmos, Virginia Morales and Balmelli, Gustavo and Donagh, Patricio Mac and Lord, Roger and Hernández, Carmelo and Zhang, Pu and et al.}, year={2020}, month={Mar}, pages={102082} }
 @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}, 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{chudy_chudy_kanieski da silva_cubbage_rubilar_lord_2020, title={Profitability and risk sources in global timberland investments}, volume={111}, ISSN={1389-9341}, url={http://dx.doi.org/10.1016/j.forpol.2019.102037}, DOI={10.1016/j.forpol.2019.102037}, abstractNote={As a long-term investment, timberland investments offer financial benefits including portfolio diversification, attractive risk/return profile, an inflation hedge, and the potential of cash flow. Based on interviews with experts regarding ranges of input parameters used in single-hectare financial models and Monte Carlo simulation method, we examine what are the main factors that influence internal rates of returns (IRRs) in several global timber plantation investment opportunities: loblolly pine on the U.S. Atlantic coastal plain; Douglas-fir plantations in the western U.S.; loblolly pine and eucalyptus plantations in Brazil; radiata pine and eucalyptus plantations in Chile; and pine and oak stands in Poland. The results show that excluding the price of land, biological growth and timber prices were the most influential variables that impacted the IRRs across global timberland investments. In addition, some country-specific factors, such as planting costs (Chile) and management costs (Poland and the U.S.), were identified as crucial when considering timberland investments in these countries. Investments in South America’s pine plantations are characterized by the same level of returns as eucalyptus opportunities, but with lower risk. The same was found for Douglas-fir investments in the Pacific Northwest compared to loblolly pine in the U.S. South. If Poland were an investable alternative, which is not the case so far, any investments in oak and pine stands are not recommended yet, given that for the same level of risk, better returns may be achieved in Douglas-fir plantations in the U.S. PNW. The Monte Carlo method utilized provides easily interpretable representation of the robustness of timberland investment estimates in selected regions and should become standard practice in forest-business decision making. However, more accurate probability density functions need to be determined in further research, using, for instance, historical data and kernel density estimation, rather than “lack of information” (triangular) distributions.}, journal={Forest Policy and Economics}, publisher={Elsevier BV}, author={Chudy, R.P. and Chudy, K.A. and Kanieski da Silva, B. and Cubbage, F.W. and Rubilar, R. and Lord, R.}, year={2020}, month={Feb}, pages={102037} }
 @article{albaugh_fox_cook_raymond_rubilar_campoe_2019, title={Forest Fertilizer Applications in the Southeastern United States from 1969 to 2016}, volume={65}, ISSN={["1938-3738"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85065724434&partnerID=MN8TOARS}, DOI={10.1093/forsci/fxy058}, abstractNote={This study presents forest fertilization and carbon sequestered from fertilization in the southeastern United States in the context of newly available silviculture management information. Maximum annual fertilized forest area in the southeastern United States occurred in 1999 when 1.58 million acres were fertilized. Since then, the fertilized area has generally declined, and in 2016, 589,000 acres were fertilized. This decline is likely related to new research and changes in economic conditions. Recent research has determined that lower, more frequent nutrient doses gave the same biological response as larger, less frequent doses; improved our understanding and use of urease inhibitors; and quantified the upper limit to pine productivity in the southeast United States. All of these factors combined with economic concerns including the continued low number of housing starts, a large inventory of stands with trees that are already sawtimber size, and low sawtimber prices influence forest managers’ decisions about fertilization. However, fertilization increases carbon sequestration in forests, and carbon markets that recognize this contribution to sequestration are developing and may provide additional income to forest managers and, ultimately, increase the area fertilized.}, number={3}, journal={FOREST SCIENCE}, author={Albaugh, Timothy J. and Fox, Thomas R. and Cook, Rachel L. and Raymond, Jay E. and Rubilar, Rafael A. and Campoe, Otavio C.}, year={2019}, month={Jun}, pages={355–362} }
 @article{albaugh_fox_maier_campoe_rubilar_cook_raymond_alvares_stape_2018, title={A common garden experiment examining light use efficiency and heat sum to explain growth differences in native and exotic Pinus taeda}, volume={425}, ISSN={["1872-7042"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85047245176&partnerID=MN8TOARS}, DOI={10.1016/j.foreco.2018.05.033}, abstractNote={Previous work indicates that Pinus taeda L. grows faster and has a higher carrying capacity when grown outside its native range. We were interested in examining the hypotheses that growth, light use efficiency (volume growth and absorbed photosynthetically active radiation relationship, LUE) and volume growth per unit heat sum is the same for native and exotic plantations. To test these hypotheses, we installed a common garden experiment where the same six genetic entries of P. taeda (four clonal varieties, one open pollinated family and one control mass pollinated family) were planted at three densities (618, 1235, and 1853 stems ha−1) with three or four replications at three sites (Virginia (VA), and North Carolina (NC) in the United States and Paraná State in Brazil (BR)). The VA and BR sites were outside the native range of P. taeda. After five years of growth, the BR site had larger trees and stand scale basal area and volume were increasing faster than the other sites. Site did not affect LUE but density and genetic entry did. The sites were at different latitudes but the average photosynthetically active radiation at the top of the canopy was similar for the years when all sites were operational, likely because the BR site receives more rain annually and the cloudiness associated with the rain may have reduced available light. We estimated an hourly heat sum where the daytime temperature was between 5 and 38 °C, hours where vapor pressure deficit exceeded 1.5 kPa and days following nights where nighttime temperatures were less than 0 °C were excluded. Site was significant for the cumulative volume and heat sum relationship, for a given level of cumulative degree hours the sites ranked BR > VA > NC in cumulative volume. The different growth per unit of degree hours for each site indicated that something other than the heat sum was causing the observed difference in growth. Other factors including respiration and extreme climatic conditions may contribute to growth differences per unit degree hour and including these differences in the analysis would require a more detailed modeling effort to examine. The sites used in this study are ideally suited to continue testing additional hypotheses to explain the different growth between native and exotic P. taeda plantations because they have the same genotypes at all sites and consequently eliminate differences in genetics as a potential explanation for observed growth differences.}, journal={FOREST ECOLOGY AND MANAGEMENT}, author={Albaugh, Timothy J. and Fox, Thomas R. and Maier, Chris A. and Campoe, Otavio C. and Rubilar, Rafael A. and Cook, Rachel L. and Raymond, Jay E. and Alvares, Clayton A. and Stape, Jose L.}, year={2018}, month={Oct}, pages={35–44} }
 @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_blevins_allen_albaugh_fox_stape_rubilar_2010, title={Characterization of foliar macro- and micronutrient concentrations and ratios in loblolly pine plantations in the southeastern United States}, volume={34}, number={2}, journal={Southern Journal of Applied Forestry}, author={Albaugh, J. M. and Blevins, L. and Allen, H. L. and Albaugh, T. J. and Fox, T. R. and Stape, J. L. and Rubilar, R. A.}, year={2010}, pages={53–64} }
 @article{cubbage_koesbandana_mac donagh_rubilar_balmelli_morales olmos_de la torre_murara_hoeflich_kotze_et al._2010, title={Global timber investments, wood costs, regulation, and risk}, volume={34}, ISSN={0961-9534}, url={http://dx.doi.org/10.1016/j.biombioe.2010.05.008}, DOI={10.1016/j.biombioe.2010.05.008}, abstractNote={We estimated financial returns and wood production costs in 2008 for the primary timber plantation species. Excluding land costs, returns for exotic plantations in almost all of South America – Brazil, Argentina, Uruguay, Chile, Colombia, Venezuela, and Paraguay – were substantial. Eucalyptus species returns were generally greater than those for Pinus species in each country, with most having Internal Rates of Return (IRRs) of 20% per year or more, as did teak. Pinus species in South America were generally closer to 15%, except in Argentina, where they were 20%. IRRs were less, but still attractive for plantations of coniferous or deciduous species in China, South Africa, New Zealand, Indonesia, and the United States, ranging from 7% to 12%. Costs of wood production at the cost of capital of 8% per year were generally cheapest for countries with high rates of return and for pulpwood fiber production, which would favor vertically integrated firms in Latin America. But wood costs at stumpage market prices were much greater, making net wood costs for open market wood more similar among countries. In the Americas, Chile and Brazil had the most regulatory components of sustainable forest management, followed by Misiones, Argentina and Oregon in the U.S. New Zealand, the United States, and Chile had the best rankings regarding risk from political, commercial, war, or government actions and for the ease of doing business. Conversely, Venezuela, Indonesia, Colombia, and Argentina had high risk ratings, and Brazil, Indonesia, and Venezuela were ranked as more difficult countries for ease of business.}, number={12}, journal={Biomass and Bioenergy}, publisher={Elsevier BV}, author={Cubbage, Frederick and Koesbandana, Sadharga and Mac Donagh, Patricio and Rubilar, Rafael and Balmelli, Gustavo and Morales Olmos, Virginia and De La Torre, Rafael and Murara, Mauro and Hoeflich, Vitor Afonso and Kotze, Heynz and et al.}, year={2010}, month={Dec}, pages={1667–1678} }
 @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{rubilar_allen_kelting_2005, title={Comparison of biomass and nutrient content equations for successive rotations of loblolly pine plantations on an Upper Coastal Plain Site}, volume={28}, ISSN={["0961-9534"]}, DOI={10.1016/j.biombioe.2004.12.001}, abstractNote={This study compared first- and second-rotation biomass and nutrient equations between successive loblolly pine plantations on an Upper Coastal Plain Site in Alabama. Nutrient concentration relationships with crown position were explored in order to evaluate their significance for biomass studies determinations. Trees were destructively sampled from across the diameter distribution of the stand for each rotation. Tissues were separated into foliage, branch, stemwood, and stembark and analyzed for nutrient concentration and dry weight. Distance from the top of the tree was recorded for all tissues of the selected second-rotation trees and plotted against nutrient concentrations. Regression equations for individual tree tissue biomass and nutrient content were fit for each rotation and compared. Analyses of nutrient concentration relationships with crown position indicated that mobile nutrient (N, P, K, Mg, S, and Zn) concentrations of stemwood, bark, and branches decreased with distance from the top of the tree and height of the live crown. Foliar nutrient concentrations and non-mobile nutrients (Ca and B) for other tissues showed no patterns with tree height. Stemwood biomass regression equations were equivalent after two rotations. However, biomass and nutrient content regression equations for foliage, branches, and bark differed between rotations. Major differences between rotations were in stemwood N and P, and foliage, branch and bark B concentrations, which suggested reduced availability of these nutrients in the second-rotation stand.}, number={6}, journal={BIOMASS & BIOENERGY}, author={Rubilar, RA and Allen, HL and Kelting, DL}, year={2005}, pages={548–564} }
 @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} }
 @inproceedings{rubilar_mckeand_allen_2003, title={Dominance and stand structure analysis in a GxE interaction trial}, booktitle={Proceedings of the 27th Southern Forest Tree Improvement Conference}, author={Rubilar, R. and McKeand, S. E. and Allen, H. L.}, year={2003}, pages={34–37} }
 @inproceedings{mckeand_grissom_rubilar_allen_2003, title={Responsiveness of diverse families of loblolly pine to fertilization: eight-year results from SETRES-2}, booktitle={Proceedings of the 27th Southern Forest Tree Improvement Conference}, author={McKeand, S. E. and Grissom, J. E. and Rubilar, R. and Allen, H. L.}, year={2003}, pages={30–33} }