Browsing by Author "Albaugh, Timothy J."

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    Assessing the utility of NAIP digital aerial photogrammetric point clouds for estimating canopy height of managed loblolly pine plantations in the southeastern United States
    Ritz, Alison L.; Thomas, Valerie A.; Wynne, Randolph H.; Green, P. Corey; Schroeder, Todd A.; Albaugh, Timothy J.; Burkhart, Harold E.; Carter, David R.; Cook, Rachel L.; Campoe, Otavio C.; Rubilar, Rafael A.; Rakestraw, Jim (Elsevier, 2022-09)
    Remote sensing offers many advantages to supplement traditional, ground-based forest measurements, such as limiting time in the field and fast spatial coverage. Data from airborne laser scanning (lidar) have provided accurate estimates of forest height, where, and when available. However, lidar is expensive to collect, and wall-to-wall coverage in the United States is lacking. Recent studies have investigated whether point clouds derived from digital aerial photogrammetry (DAP) can supplement lidar data for estimating forest height due to DAP's lower costs and more frequent acquisitions. We estimated forest heights using point clouds derived from the National Agricultural Imagery Program (NAIP) DAP program in the United States to create a predicted height map for managed loblolly pine stands. For 534 plots in Virginia and North Carolina, with stand age ranging from 1 year to 42 years old, field-collected canopy heights were regressed against the 90th percentile of heights derived from NAIP point clouds. Model performance was good, with an R2 of 0.93 and an RMSE of 1.44 m. However, heights in recent heavily thinned stands were consistently underestimated, likely due to between-row shadowing leading to a poor photogrammetric solution. The model was applied to non-thinned evergreen areas in Virginia, North Carolina, and Tennessee to produce a multi-state 5 m x 5 m canopy height map. NAIP-derived point clouds are a viable means of predicting canopy height in southern pine stands that have not been thinned recently.
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    Biomass and nutrient mass of Acacia dealbata and Eucalyptus globulus bioenergy plantations
    Albaugh, Timothy J.; Rubilar, Rafael A.; Maier, Christopher A.; Acuna, Eduardo A.; Cook, Rachel L. (2017-02)
    We quantified biomass and nutrient accumulation of Acacia dealbata Link and Eucalyptus globulus Labill. planted at stem densities of 5000 and 15000 ha(-1) in a bioenergy plantation in Chile. We tested the hypotheses that species and stocking will not affect biomass or nutrient accumulation. Species and stocking did not affect biomass accumulation after five years; however, species and stocking did influence nutrient mass. A. dealbata had higher nitrogen mass than E. globulus for total (397 kg ha(-1) more, i.e., 126% higher), foliage (188 kg ha(-1), 218%), branch (55 kg ha(-1), 95%), stem (120 kg ha(-1), 86%), and root (34 kg ha (-1), 109%) components, likely because A. dealbata fixes nitrogen. A. dealbata had lower calcium mass than E. globulus for branch (111 kg ha(-1), 60%) and stem (69 kg ha(-1), 39%) components. Root nitrogen and phosphorus masses and foliage, branch and root boron masses were significantly lower with a stocking density of 5000 ha(-1). Low stocking produced the same amount of total biomass as high stocking for both species and would be less expensive to plant. A. dealbata had higher nitrogen mass and likely increased soil nitrogen. E. globulus had high calcium mass in the stem and branches; off-site losses could be mitigated with stem-only harvests and debarking of stems in the field. Given the rainfall patterns and water availability constraints in Chile, additional criteria including water use efficiency would be required to determine the best species for bioenergy plantations in Chile. (C) 2017 Elsevier Ltd. All rights reserved.
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    A common garden experiment examining light use efficiency and heat sum to explain growth differences in native and exotic Pinus taeda
    Albaugh, Timothy J.; Fox, Thomas R.; Maier, Christopher A.; Campoe, Otavio C.; Rubilar, Rafael A.; Cook, Rachel L.; Raymond, Jay E.; Alvares, Clayton A.; Stape, Jose L. (2018-10-01)
    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 Parana 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 degrees C, hours where vapor pressure deficit exceeded 1.5 kPa and days following nights where nighttime temperatures were less than 0 degrees 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.
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    Comparative water use in short-rotation Eucalyptus benthamii and Pinus taeda trees in the Southern United States
    Maier, Christopher A.; Albaugh, Timothy J.; Cook, Rachel I.; Hall, Kevin; McInnis, Daniel; Johnsen, Kurt H.; Johnson, John; Rubilar, Rafael A.; Vose, James M. (2017-08-01)
    Short rotation Eucalyptus plantations offer great potential for increasing wood-fiber production in the southern United States. Eucalyptus plantations can be highly productive (>35 m(3) ha(-1) year but they may use more water than intensively managed pine (primarily Pinus taeda L) plantations. This has raised concern about how expansion of Eucalyptus plantations will affect water resources. We compared tree water use, stem growth, and WUE (kg wood per m(3) water transpired) in adjacent nine-year-old Eucalyptus benthamii and P. taeda plantations with similar stand density and leaf area. Sap flux (F-d, g cm(-2) s(-1)) was measured continuously over one year using thermal dissipation probes. Stem biomass, stem growth, tree water use (E-t, L day(-1)), canopy transpiration per unit leaf area (E-1, mmol m(-2) s(-1)), and canopy stomatal conductance (G(s), mmol m(2) s(-1)) were quantified. Eucalyptus had higher daily Fd (196.6 g cm(-2) day(-1)) and mean daily E-t (24.6 L day(-1)) than pine (105.8 g cm(-2) day(-1), 15.2 L day(-1)). Eucalyptus exhibited a seasonally bimodal pattern in daily E-t that did not occur in pine. Monthly E-t was23-51% higher in Eucalyptus and differences between species were greatest in the spring and fall. Annual E-t was 32% higher in Eucalyptus (9.13 m(3) H2O year(-1)) than pine (5.79 m(3) H2O year(-1)). Annual stem biomass increment was greater in Eucalyptus (Eucalyptus: 22.9; pine: 11.8 kg tree(-1) year(-1)), and Eucalyptus had greater WUE (Eucalyptus: 2.86; pine 1.72 kg biomass m(-3) H2O year(-1)). Pine exhibited a lower seasonal minimum and higher seasonal maximum leaf area index (LAI). At low LAI, there was no significant difference between species in E-l or G(s); however, at maximum LAI, pine E-l and G(s) were 46 and 43%, respectively of rates observed in Eucalyptus. The species differed in G(5) response to vapor pressure deficit (D). At a similar reference G(s) (G(s),(ref) at D =1 kPa), pine exhibited greater stomatal sensitivity to D. These results suggest that (1) Eucalyptus trees had higher sap flux and total water use than pine, (2) Eucalyptus had greater stem growth and WUE, and (3) species differences in water use were driven primarily by differences in E-l and G(s). Published by Elsevier B.V.
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    Complementarity increases production in genetic mixture of loblolly pine (Pinus taeda L.) throughout planted range
    Carter, David R.; Albaugh, Timothy J.; Camo, Otávio C.; Grossman, Jake J.; Rubilar, Rafael A.; Sumnall, Matthew; Maier, Christopher A.; Cook, Rachel L.; Fox, Thomas R. (ESA, 2020-09-01)
    Increased genotypic diversity has been associated with increased biomass production in shortrotation tree species. Increasing the genotypic diversity of loblolly pine (Pinus taeda L.) in an attempt to increase productivity has not been extensively studied nor tested operationally or over long durations (i.e., >7 yr). We used genetically mixed and pure rows of loblolly pine growing throughout its planted range— Virginia, North Carolina, and Brazil—to test the effects of genetic mixing on volume production. There were no significant effects of mixing rows compared to pure rows on uniformity or mortality. Under intensive silviculture, individual trees planted in mixed rows had approximately 7% greater volume than those in the pure rows (estimate = 0.015 m³/tree ± 0.006) in the final year of measurement—year 8 for Brazil and year 10 for North Carolina and Virginia. Scaling the increase in individual stem volume under mixed rows and intensive silviculture to 1235 stems ha⁻¹ would equate to an additional 1.85 m³∙ha⁻¹∙yr⁻¹ in mean annual increment. Measuring the net biodiversity effect, our data suggest the positive growth response is driven by complementarity and not selection, meaning both genetic entries tend to grow larger when grown together. Additional trials are necessary to test the effects of mixing rows across large plots and to assess whether this increase is sustained throughout the rotation. If this increasing trend were to hold for intensively managed plantations, strategically mixing rows to increase productivity could be a valuable addition to an intensively managed plantation requiring relatively little added operational consideration to implement.
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    Crown architecture, crown leaf area distribution, and individual tree growth efficiency vary across site, genetic entry, and planting density
    Albaugh, Timothy J.; Maier, Christopher A.; Campoe, Otavio C.; Yanez, Marco A.; Carbaugh, Eric D.; Carter, David R.; Cook, Rachel L.; Rubilar, Rafael A.; Fox, Thomas R. (2020-02)
    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.
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    Juvenile Southern Pine Response to Fertilization Is Influenced by Soil Drainage and Texture
    Albaugh, Timothy J.; Fox, Thomas R.; Allen, H. Lee; Rubilar, Rafael A. (MDPI, 2015-08-14)
    We examined three hypotheses in a nutrient dose and application frequency study installed in juvenile (aged 2–6 years old) Pinus stands at 22 sites in the southeastern United States. At each site, eight or nine treatments were installed where nitrogen was applied at different rates (0, 67, 134, 268 kg ha−1) and frequencies (0, 1, 2, 4 and 6 years) in two or four replications. Phosphorus was applied at 0.1 times the nitrogen rate and other elements were added as needed based on foliar nutrient analysis to insure that nutrient imbalances were not induced with treatment. Eight years after treatment initiation, the site responses were grouped based on texture and drainage characteristics: soil group 1 consisted of poorly drained soils with a clayey subsoil, group 2 consisted of poorly to excessively drained spodic soils or soils without a clay subsoil, and group 3 consisted of well-drained soils with a clayey subsoil. We accepted the first hypothesis that site would be a significant factor explaining growth responses. Soil group was also a significant factor explaining growth response. We accepted our second hypothesis that the volume growth-cumulative dose response function was not linear. Volume growth reached an asymptote in soil groups 1 and 3 between cumulative nitrogen doses of 300–400 kg ha−1. Volume growth responses continued to increase up to 800 kg ha−1 of cumulatively applied nitrogen for soil group 2. We accepted our third hypothesis that application rate and frequency did not influence the growth response when the cumulative nitrogen dose was equivalent. There was no difference in the growth response for comparisons where a cumulative nitrogen dose of 568 kg ha−1 was applied as 134 kg ha−1 every two years or as 269 kg ha−1 every four years, or where 269 kg ha−1 of nitrogen was applied as four applications of 67 kg ha−1 every two years or as two applications of 134 kg ha−1 every four years. Clearly, the sites examined here were limited by nitrogen and phosphorus, and applications of these elements to young stands effectively ameliorated these limitations. However, there were differences in the response magnitude that were related to soil texture and drainage. Juvenile fertilizer applications resulted in high stocking levels early in the rotation; this condition should be considered when undertaking juvenile fertilization programs.
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    Leveraging 35 years of Pinus taeda research in the southeastern US to constrain forest carbon cycle predictions: regional data assimilation using ecosystem experiments
    Thomas, R. Quinn; Brooks, Evan B.; Jersild, Annika L.; Ward, Eric J.; Wynne, Randolph H.; Albaugh, Timothy J.; Dinon-Aldridge, Heather; Burkhart, Harold E.; Domec, Jean-Christophe; Fox, Thomas R.; González-Benecke, Carlos; Martin, Timothy A.; Noormets, Asko; Sampson, David A.; Teskey, Robert O. (Copernicus, 2017-07-26)
    Predicting how forest carbon cycling will change in response to climate change and management depends on the collective knowledge from measurements across environmental gradients, ecosystem manipulations of global change factors, and mathematical models. Formally integrating these sources of knowledge through data assimilation, or model-data fusion, allows the use of past observations to constrain model parameters and estimate prediction uncertainty. Data assimilation (DA) focused on the regional scale has the opportunity to integrate data from both environmental gradients and experimental studies to constrain model parameters. Here, we introduce a hierarchical Bayesian DA approach (Data Assimilation to Predict Productivity for Ecosystems and Regions, DAPPER) that uses observations of carbon stocks, carbon fluxes, water fluxes, and vegetation dynamics from loblolly pine plantation ecosystems across the southeastern US to constrain parameters in a modified version of the Physiological Principles Predicting Growth (3-PG) forest growth model. The observations included major experiments that manipulated atmospheric carbon dioxide (CO2) concentration, water, and nutrients, along with nonexperimental surveys that spanned environmental gradients across an 8.6ĝ€ × ĝ€105ĝ€km2 region. We optimized regionally representative posterior distributions for model parameters, which dependably predicted data from plots withheld from the data assimilation. While the mean bias in predictions of nutrient fertilization experiments, irrigation experiments, and CO2 enrichment experiments was low, future work needs to focus modifications to model structures that decrease the bias in predictions of drought experiments. Predictions of how growth responded to elevated CO2 strongly depended on whether ecosystem experiments were assimilated and whether the assimilated field plots in the CO2 study were allowed to have different mortality parameters than the other field plots in the region. We present predictions of stem biomass productivity under elevated CO2, decreased precipitation, and increased nutrient availability that include estimates of uncertainty for the southeastern US. Overall, we (1) demonstrated how three decades of research in southeastern US planted pine forests can be used to develop DA techniques that use multiple locations, multiple data streams, and multiple ecosystem experiment types to optimize parameters and (2) developed a tool for the development of future predictions of forest productivity for natural resource managers that leverage a rich dataset of integrated ecosystem observations across a region.
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    Mid-Rotation Response of Soil Preparation Intensity and Timing of Weed Control on Radiata Pine
    Bozo, Daniel; Rubilar, Rafael; Espinoza, Yosselin; Campoe, Otavio; Cook, Rachel; Carter, David; Albaugh, Timothy J. (MDPI, 2022-10-21)
    A good instance to improve the availability of resources for tree planting is during the establishment of stands, increasing the survival and initial growth of plants. Despite the common use of soil preparation, there are uncertainties about its long-term effects on stand growth and the intensity required. Weeds compete with crop plants for site resources, such as light, water, and nutrients, so evaluating the best time to apply this treatment is key. The objective of this study is to quantify the effects of soil preparation intensity and the timing of weed control on the long-term growth responses of radiata pine on a metamorphic soil in Chile. The study was established on a split-plot design with cultivation as the main plot treatment (shovel, subsoiling, and disking) and weed control as subplots (none, pre- and post-, and only post-planting) to remove all competing vegetation. Subsoiling was performed to 80 cm and disking to a 30 cm depth. Trees were planted in 2013 and were measured annually for diameter at breast height (DBH) and total height. Nine years after establishment, soil preparation treatments with weed control applied at pre- and post-establishment showed the lowest mortality. The best responses in cumulative volume were observed for disking and subsoiling plus weed control at pre-establishment, and the lowest responses were observed for treatments not including weed control. Weed control was the key treatment providing good growth response. Interestingly, the hypothesis that deep soil tillage was required on long dry season sites such as these was rejected given that disking to 30 cm provided equal or even larger growth responses.
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    A Model to Estimate Leaf Area Index in Loblolly Pine Plantations Using Landsat 5 and 7 Images
    Kinane, Stephen M.; Montes, Cristian R.; Albaugh, Timothy J.; Mishra, Deepak R. (MDPI, 2021-03-17)
    Vegetation indices calculated from remotely sensed satellite imagery are commonly used within empirically derived models to estimate leaf area index in loblolly pine plantations in the southeastern United States. The data used to parameterize the models typically come with observation errors, resulting in biased parameters. The objective of this study was to quantify and reduce the effects of observation errors on a leaf area index (LAI) estimation model using imagery from Landsat 5 TM and 7 ETM+ and over 1500 multitemporal measurements from a Li-Cor 2000 Plant Canopy Analyzer. Study data comes from a 16 quarter 1 ha plot with 1667 trees per hectare (2 m × 3 m spacing) fertilization and irrigation research site with re-measurements taken between 1992 and 2004. Using error-in-variable methods, we evaluated multiple vegetation indices, calculated errors associated with their observations, and corrected for them in the modeling process. We found that the normalized difference moisture index provided the best correlation with below canopy LAI measurements (76.4%). A nonlinear model that accounts for the nutritional status of the stand was found to provide the best estimates of LAI, with a root mean square error of 0.418. The analysis in this research provides a more extensive evaluation of common vegetation indices used to estimate LAI in loblolly pine plantations and a modeling framework that extends beyond the typical linear model. The proposed model provides a simple to use form allowing forest practitioners to evaluate LAI development and its uncertainty in historic pine plantations in a spatial and temporal context.
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    A New Approach for Modeling Volume Response from Mid-Rotation Fertilization of Pinus taeda L. Plantations
    Scolforo, Henrique F.; Montes, Cristian R.; Cook, Rachel L.; Lee Allen, Howard; Albaugh, Timothy J.; Rubilar, Rafael A.; Campoe, Otavio C. (MDPI, 2020-06-06)
    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.
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    Readily available resources across sites and genotypes result in greater aboveground growth and reduced fine root production in Pinus taeda
    Shively, Timothy J.; Cook, Rachel; Maier, Chris A.; Garcia, Kevin; Albaugh, Timothy J.; Campoe, Otavio; Leggett, Zakiya (Elsevier, 2022-10)
    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 mot 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 mot 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 mot production, which supports the employment of these intensive silvicultural practices.
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    Sentinel-2 Leaf Area Index Estimation for Pine Plantations in the Southeastern United States
    Cohrs, Chris W.; Cook, Rachel L.; Gray, Josh M.; Albaugh, Timothy J. (MDPI, 2020-04-29)
    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.