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The future climate of the southeastern USA is predicted to be warmer, drier and more variable in rainfall, which may increase drought frequency and intensity. Loblolly pine (Pinus taeda) is the most important commercial tree species in the world and is planted on ~11 million ha within its native range in the southeastern USA. A regional study was installed to evaluate effects of decreased rainfall and nutrient additions on loblolly pine plantation productivity and physiology. Four locations were established to capture the range-wide variability of soil and climate. Treatments were initiated in 2012 and consisted of a factorial combination of throughfall reduction (approximate 30% reduction) and fertilization (complete suite of nutrients). Tree and stand growth were measured at each site. Results after two growing seasons indicate a positive but variable response of fertilization on stand volume increment at all four sites and a negative effect of throughfall reduction at two sites. Data will be used to produce robust process model parameterizations useful for simulating loblolly pine growth and function under future, novel climate and management scenarios. The resulting improved models will provide support for developing management strategies to increase pine plantation productivity and carbon sequestration under a changing climate. Published version

In forest inventory, traditional ground-based resource assessments are often expensive and time-consuming forcing managers to reduce sample sizes to meet budgetary and logistical constraints. Small area estimation (SAE) is a class of statistical estimators that uses a combination of traditional survey data and linearly related auxiliary information to improve estimate precision. These techniques have been shown to improve the precision of stand-level inventory estimates in loblolly pine plantations using lidar height percentiles and thinning status as covariates. In this study, the effects of reduced lidar point-cloud densities and lower digital elevation model (DEM) spatial resolutions were investigated for total planted volume estimates using area-level SAE models. In the managed Piedmont pine plantation conditions evaluated, lower lidar point-cloud densities and DEM spatial resolutions were found to have minimal effects on estimates and precision. The results of this study are promising to those interested in incorporating SAE methods into forest inventory programs. Forest Modeling Research Cooperative; Department of Forest Resources and Environmental Conservation; Virginia Tech; USDA McIntire-Stennis program [VA-136630] This work was supported by the Forest Modeling Research Cooperative; the Department of Forest Resources and Environmental Conservation; Virginia Tech; and the USDA McIntire-Stennis program (Project No. VA-136630). Public domain – authored by a U.S. government employee

Accurate prediction of stem diameter is an important prerequisite of forest management. In this study, an appropriate stem taper function was developed for upper stem diameter estimation of white birch (Betula platyphylla Sukaczev) in ten sub-regions of the Daxing'an Mountains, northeast China. Three commonly used taper functions were assessed using a diameter and height dataset comprising 1344 trees. A first-order continuous-time error structure accounted for the inherent autocorrelation. The segmented model of Max and Burkhart (For Sci 22:283-289, 1976. 10.1093/forestscience/22.3.283) and the variable exponent taper function of Kozak (For Chron 80:507-515, 2004. 10.5558/tfc80507-4) described the data accurately. Owing to its lower multicollinearity, the Max and Burkhart (1976) model is recommended for diameter estimation at specific heights along the stem for the ten sub-regions. After comparison, the Max and Burkhart (1976) model was refitted using nonlinear mixed-effects techniques. Mixed-effects models would be used only when additional upper stem diameter measurements are available for calibration. Differences in region-specific taper functions were indicated by the method of the non-linear extra sum of squares. Therefore, the particular taper function should be adjusted accordingly for each sub-region in the Daxing'an Mountains. National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [31570624]; Applied Technology Research and Development Plan Project of Heilongjiang Province [GA19C006]; Fundamental Research Funds for Central UniversitiesFundamental Research Funds for the Central Universities [2572019CP15] This study was financially supported by the National Natural Science Foundation of China (31570624), Applied Technology Research and Development Plan Project of Heilongjiang Province (GA19C006), and Fundamental Research Funds for Central Universities (2572019CP15).

Forest conservation buffers provide ecosystem services such as soil and water conservation, wildlife habitat, and clean air. This research studied the experiences and intentions of participants in forest buffer contract programs in Virginia, USA provided by governmental conservation agencies. These programs offer technical assistance and share costs of establishment and maintenance for a period of time typically between 2 and 15 years. Program participant reflections about their experience and intention to retain their forest buffer after their cost-share contract ends were measured. Two-hundred and fifty-one program participants received a mail survey and 136 were returned (response rate = 54%). Two-step cluster analysis grouped respondents into four participant types based on responses to questions about buffer maintenance and costs, and perceived environmental benefits. Discontented and Doubtful respondents (23.4%) experienced financial and maintenance challenges. They also were doubtful about environmental benefits. Contented and Confident respondents (28.2%) experienced minimal financial and maintenance difficulties, and were confident that their buffers provide environmental benefits. Benefited with Burden respondents (22.6%) also were confident about environmental benefits, but experienced burdensome maintenance and costs. Skeptical without Strife respondents (25.8%) were not convinced their buffers provide environmental benefits, but have not had problems with maintenance or costs. A Kruskal-Wallis non-parametric test (alpha = 0.05) indicated that Discontented and Doubtful respondents are least likely to retain their buffer after their cost-share contract expires (rank sum = 42.2) and Contented and Confident are most likely (rank sum = 82.8). Benefited with Burden and Skeptical without Strife respondents (rank sum = 59.7 and = 59.8, respectively) were statistically similar to their Discontented and Doubtful counterparts, but slightly more likely to keep their buffer after their contract expires. Overall, Discontented and Doubtful and Benefited with Burden respondents had larger parcels of land and represented the largest percentage of full-time farmers, whereas Contented and Confident and Skeptical without Strife respondents had smaller parcels and were most likely to be part-time farmers or female. Findings suggest distinctions between types are clear along the onus of management, not necessarily perspectives on conservation. The two most influential drivers of program participation were cost-share assistance and water quality, whereas their most important management objective was improving land health. Public domain – authored by a U.S. government employee

Loblolly pine (Pinus taeda L.) is one of the most widely planted tree species globally. As the reliability of estimating forest characteristics such as volume, biomass and carbon becomes more important, the necessary resources available for assessment are often insufficient to meet desired confidence levels. Small area estimation (SAE) methods were investigated for their potential to improve the precision of volume estimates in loblolly pine plantations aged 9-43. Area-level SAE models that included lidar height percentiles and stand thinning status as auxiliary information were developed to test whether precision gains could be achieved. Models that utilized both forms of auxiliary data provided larger gains in precision compared to using lidar alone. Unit-level SAE models were found to offer additional gains compared with area-level models in some cases; however, area-level models that incorporated both lidar and thinning status performed nearly as well or better. Despite their potential gains in precision, unit-level models are more difficult to apply in practice due to the need for highly accurate, spatially defined sample units and the inability to incorporate certain area-level covariates. The results of this study are of interest to those looking to reduce the uncertainty of stand parameter estimates. With improved estimate precision, managers, stakeholders and policy makers can have more confidence in resource assessments for informed decisions. Forest Modeling Research Cooperative; Department of Forest Resources and Environmental Conservation, Virginia Tech; United States Department of Agriculture McIntire-Stennis program [VA-136630] The Forest Modeling Research Cooperative, the Department of Forest Resources and Environmental Conservation, Virginia Tech and the United States Department of Agriculture McIntire-Stennis program (Project No. VA-136630) are all gratefully acknowledged for supporting this project. Public domain – authored by a U.S. government employee

Lake ice phenology parameters (dates of ice onset and thaw) provide an integrative climatic description of autumn to springtime conditions. Interannual variations in lake ice duration and thickness allow estimates of local climatic variability. In addition, long-term changes in lake ice phenology may provide a robust indication of climatic change. The relationship between lake ice and climate enables the use of process-based models for predicting the dates of freeze-up and thaw. LIMNOS (Lake Ice Model Numerical Operational Simulator) is one such model, which was originally designed to simulate the ice phenology of several lakes in southern Wisconsin. In this study, LIMNOS is modified to run globally on a 0.5° by 0.5° latitude-longitude grid using average monthly climate data. We initially simulate the ice phenology for lakes of 5- and 20-m mean depths across the northern hemisphere to demonstrate the effects of lake depth, latitude, and elevation on ice phenology. To evaluate the results of LIMNOS we also simulate the ice phenology of 30 lakes across the northern hemisphere which have long-term ice records. LIMNOS reproduces the general geographic patterns of ice-on and ice-off dates, although ice-off dates tend to occur later in the model. Lakes with extreme depths, surface areas, or precipitation are simulated less accurately than small, shallow lakes. This study reveals strengths and weaknesses of LIMNOS and suggests aspects which need improving. Future investigations should focus on the use of geographically extensive lake ice observations and modeling to elucidate patterns of climatic variability and/or climate change. National Science Foundation (U.S.) - DEB-9011660 National Science Foundation (U.S.) - DEB-9416810 United States. National Aeronautics and Space Administration - NGT-30346 United States. National Aeronautics and Space Administration – NAG5-3513 University of Wisconsin–Madison. Institute for Environmental Studies. Climate, People, and Environment Program (CPEP)

Survival and growth of planted tree species are common indices used to evaluate success of wetland restoration efforts used to compensate for wetland losses. Restoration efforts on marginal agricultural lands have typically resulted in less than satisfactory survival and growth of desired tree species. In an attempt to determine the effects of bottomland hardwood silvicultural methods on the survival and growth of pioneer tree species, this study evaluated combinations of five mechanical site-preparation techniques (mound, bed, rip, disk, pit), four levels of planting stock (gallon, tubeling, bare root, and direct seed), and three planting aids (mat, tube, none) on the four-year survival and growth of American sycamore planted in an old field riparian area in the Piedmont of Virginia. After four growing seasons, results indicated that mounding mechanical site preparation combined with gallon (3.8 L) planting stock provided the most positive influences on mean survival (100%), height (4.72 m), and groundline diameter (9.52 cm), and resulted in the greatest aboveground dry biomass accumulation (5.44 Mg/ha/year). These treatments may be economically viable for restoration and mitigations efforts, and could offer other economic alternatives such as short-rotation woody crops, which might make restoration efforts in marginal old field areas more attractive to private landowners. Published version

Active forest management operations, such as regeneration harvests, can reduce hazardous fuel loads and alter fuel structure, potentially minimizing extreme wildfire conditions while maintaining ecosystem services, such as wildlife habitat and water quality. Regeneration harvests of differing intensities (clearcut, high-retention shelterwood, and low-retention shelterwood) were first applied between 1995 and 1996 to three sites on the George Washington-Jefferson National Forest in the Ridge and Valley Province of Virginia, USA. Over two decades after the clearcut was conducted and 11–12 years after the overwood was removed in the shelterwood stands, woody debris, litter, and duff masses and depths were quantified. One-hour fuel loads were greater in clearcut units than in high-retention shelterwood, low-retention shelterwood, or control units. Ten-hour fuel loads were greater in clearcut and low-retention shelterwood units than in high-retention shelterwood and control units. No significant differences in 100-hour fuels were observed between treatments. Control units contained more rotten and total 1000-hour fuels than all other treatments. The total woody debris load was less in the clearcut and high-retention shelterwood than in the low-retention shelterwood and control. High-retention shelterwood woody fuel depth was greater than clearcut woody fuel depth. Litter and duff loads were less in treated units than in the control units. Total fuel load (woody fuel load + litter load + duff load) was greater in the control than the silvicultural treatments. Litter depth did not differ between treatments, while duff depth was greater in the control than in the treated units. Using the computer modeling software, BehavePlus 6.0.0, these alterations to fuel loads and depths led to increased values in the control units for six fire behavior parameters. Predicted surface flame length in the low-retention shelterwood was the only modeled value that was not less than control values. Overall, these results indicated that harvest intensity and timing may have long-term effects on down and dead woody fuels, forest floor depth, and potential fire behavior. Clearcutting reduced fire behavior most, followed by the high-retention shelterwood system. The potential differences in slash and debris generated by varying shelterwood systems may impact long-term fuel and fire dynamics. Published version

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. Public domain – authored by a U.S. government employee

Using a large dataset compiled from studies over the years covering 23 tree species, we developed methods to estimate total and components (stem, bark, branch, and foliage) of aboveground live tree biomass. Missing components in the dataset were imputed using species-specific or generalized (species combined into softwood and hardwood groups) Dirichlet imputation. Geometric means of the imputed stem wood proportions were 8% and 9% higher than the observed geometric mean of stem wood proportions in softwood and hardwood species, respectively. For other components, the differences were within 1%. On average, the component ratio method (CRM), used for the official United States forest carbon inventories, underestimated the aboveground biomass (AGB, kg) predictions by 3.7% with a very wide range (-70.3% to 31.6%). Compared with the CRM approach, equations developed in this study reduced RMSE of AGB by as much as 145.0%. On average, new equations reduced RMSE in predicting individual-tree AGB by 15.5% compared with the CRM approach and by 3.9% compared with a calibration of CRM AGB. Predicting AGB as a function of stem volume was not as accurate as using direct AGB equations. Generalized component ratio equations may be suitable for the stem wood component but were highly biased for other components. Public domain – authored by a U.S. government employee

With continued global change as a result of land use changes, invasive species and changing climatic patterns, it is becoming increasingly important to understand the adaptability of Senegalia senegal provenances to maximize resilience in managed and natural populations of this species. The objective of this study is to investigate Senegalia senegal genotypic differences in water use efficiency (WUE) measured by stable C-13 isotope composition in foliage according to their ploidy levels. Secondary objectives are to discuss inherent adaptive variation related to soil pH, survival, growth indexes, gum arabic yield and WUE within provenance in the climate change context. A Senegalia senegal progeny trial, in Dahra, Senegal was used in this study: 443 adult trees consisting of 60 families nested within 4 provenances were assessed in this study. Results showed significant differences in gum yield among provenances (P = 0.0002) and families (P < 0.0001). Diamenar and Ngane provenances showed overall similar annual gum yield despite a lower tree survival rate of Ngane than Diamenar. Growth traits, especially stem volume index and crown area index were larger on Ngane provenance, which also displayed significantly higher foliar WUE and lower leaf area index (LAI) than the other provenances. WUE was positively correlated with gum yield (P = 0.0302), but the coefficient of determination was only 2%. Foliar delta C-13 varied significantly (P < 0.0001) between diploids (- 27.91 parts per thousand) and polyploids (- 27.12 parts per thousand). However, within each provenance no significant difference was found. Only 15% of isotope compositions could be explained by ploidy level variation. Differences found in growth and gum yield may be attributed to genotype-specific variation. However, a significant correlation between soil pH and tree survival rate was found (P = 0.0051; r = 0.60). This study confirmed a possible improvement of the gum arabic sector through genotype based selection. Ngane and Diamenar seem to be more profitable to grow in Dahra than the other tested provenances. Future research should investigate the effect of soil pH, other soil physical and chemical properties, and management activities to improve site quality on tree survival and gum yields among provenances. Further, more research is needed to clarify inherent traits underlying drought tolerance in the field and gum yield performance. United States Agency for International Development (USAID) as part of Feed the FutureUnited States Agency for International Development (USAID); U.S. Government's global hunger and food security initiative [AID-685-A-00-10-00194-00] We are grateful to Centre National de Recherche Forestiere for the logistical support provided during the fieldwork. We thank Mrs Momar Wade and Ibra Padane for their support in collecting data, Dr Marieme Fall Ba and Dr Mamadou Ousseynou Ly for their help to conduct soil analysis. A big thank to Mr Andy Laviner for his help on using the LAI 2200, and Mr David Mitchem to conduct isotope analysis of leaves. This article is made possible in part by the generous support of the American people through the United States Agency for International Development (USAID) as part of Feed the Future, the U.S. Government's global hunger and food security initiative, under the terms of Contract No. AID-685-A-00-10-00194-00 (USAID/Education and Research in Agriculture). The contents are the responsibility of the author(s) and do not necessarily reflect the views of USAID or the United States Government.

Globally, prescribed fire, harvesting, and understory mastication, alone and in combination, are common forest management practices. Timber commodities, wildlife habitat, wildfire fuel reduction, soil conservation, and water quality are frequently targeted and assessed as these practices are utilized. In the 1960s, a study of paired, first-order watersheds was established in coastal South Carolina, USA, to evaluate the long-term impacts of forest management (i.e. prescribed fire, thinning, mastication of understory vegetation) on water quantity and quality. Following Hurricane Hugo in 1989, this included salvage logging on one watershed, but not the other. In 2015, these watersheds were comprehensively evaluated to determine differences in forest species composition, fuels, and soil chemistry. Softwood basal area was greater in the managed watershed than in the unmanaged watershed and hardwood basal area was greater in the unmanaged watershed than in the managed watershed. Total fuel mass did not differ between the two watersheds, but 1-hr and 1000-hr rotten fuel mass were greater on the unmanaged watershed. Ten-hr fuel mass was greater on the managed watershed. Calcium, nitrogen, magnesium, phosphorus, potassium, and pH differed between the litter (Oi horizon) and duff (Oe + Oa horizons) of both watersheds, but carbon only differed in the duff. Mineral soil (Ultisols, 0-10 and 10-20 cm depths) calcium and phosphorus differed between the watersheds, but pH and the other chemicals did not. Collectively, these results indicated that: (1) forest management and natural disturbance on these watersheds altered long-term forest structure; (2) different species compositions and the inclusion or exclusion of salvage logging after Hurricane Hugo produced different fuel compositions that may potentially impact potential wildfire hazard and fire behavior; (3) organisms as a primary soil-forming factor were impacted by long-term management, therefore, some soil chemical properties were affected. Collectively, these analyses highlighted the broad, long-term impacts to ecosystem properties and processes that might directly and indirectly result from active forest management and natural disturbance and the scale of site-specific assessment that might be considered when landowner objectives are targeted in forest management plans and practices. Public domain – authored by a U.S. government employee

Forest tree species are increasingly subject to severe mortalities from exotic pests, pathogens, and invasive organisms, accelerated by climate change. Such forest health issues are threatening multiple species and ecosystem sustainability globally. One of the most extreme examples of forest ecosystem disruption is the extirpation of the American chestnut (Castanea dentata) caused by the introduction of chestnut blight and root rot pathogens from Asia. Asian species of chestnut are being employed as donors of disease resistance genes to restore native chestnut species in North America and Europe. To aid in the restoration of threatened chestnut species, we present the assembly of a reference genome for Chinese chestnut (C. mollissima) "Vanuxem," one of the donors of disease resistance for American chestnut restoration. From the de novo assembly of the complete genome (725.2 Mb in 14,110 contigs), over half of the sequences have been anchored to the 12 genetic linkage groups. The anchoring is validated by genetic maps and in situ hybridization to chromosomes. We demonstrate the value of the genome as a platform for research and species restoration, including signatures of selection differentiating American chestnut from Chinese chestnut to identify important candidate genes for disease resistance, comparisons of genome organization with other woody species, and a genome-wide examination of progress in backcross breeding for blight resistance. This reference assembly should prove of great value in the understanding, improvement, and restoration of chestnut species. Forest Health Initiative [137RFP, 2008-011]; United States Department of Agriculture (USDA) National Institute of Food and AgricultureUnited States Department of Agriculture (USDA) [2016-67013-24581]; USDA National Institute of Food and Agriculture Federal Appropriations [PEN04532, 1000326, NE-1833]; Foundation for the Carolinas; National Science Foundation (NSF)National Science Foundation (NSF) [1444573]; NSF Postdoctoral Research Fellowships in Biology Grant [1711950]; Institutional Development Award (IDeA) from the National Institute of GeneralMedical Sciences of the National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [P20GM109094]; American Chestnut Foundation This project was funded by the Forest Health Initiative (https://foresthealthinitiative.org/) through grant #137RFP#2008-011 to JEC. Support was also provided by the United States Department of Agriculture (USDA) National Institute of Food and Agriculture grant 2016-67013-24581 to The American Chestnut Foundation. Additional support was provided through several grants-inaid to JEC fromThe American Chestnut Foundation and to JEC andMES through the USDA National Institute of Food and Agriculture Federal Appropriations under Project PEN04532 (Accession number 1000326) and NE-1833, respectively. Construction of saturated genetic maps and root RNAseq dataset was partially supported by the Foundation for the Carolinas. Bioinformatics was supported by National Science Foundation (NSF) Award #1444573, "Standards and Cyberinfrastructure that Enable 'Big-Data' Driven Discovery for Tree Crop Research" (MES; PI Main). Emily Bellis was supported by NSF Postdoctoral Research Fellowships in Biology Grant No. 1711950. Rooksana Noorai was supported by an Institutional Development Award (IDeA) from the National Institute of GeneralMedical Sciences of the National Institutes of Health under grant number P20GM109094. Public domain – authored by a U.S. government employee

African American landownership is decreasing in the southeastern United States. At the same time, prescribed fire use, research, and outreach are increasing. This disparity between changing landowner demographics and a renewed interest in a historically prevalent land management tool has prompted a broader conversation about diversity and inclusion in outreach programs and land management preferences. Therefore, an exploratory qualitative study was conducted using semi-structured interviews with African American non-industrial private landowners (NIPLs) in southern Alabama, northern Florida, and southwestern Georgia. The objectives of this study were to address the following questions: 1) Do African American NIPLs use prescribed fire?; 2) Why do they choose or refuse to use prescribed fire?; 3) What potential constraints discourage African American NIPLs from using prescribed fire? Twenty-one African American landowners within these states were interviewed from May through August 2019. Analysis of these interviews was completed using rapid rural appraisal, a method used to quickly gather data from individuals in rural settings. The results suggested that 81% of the African American NIPLs interviewed used prescribed fire to accomplish specific land management objectives, such as hazardous fuel reduction, undesired vegetation control, timber stand improvement, pest and disease reduction, and aesthetics. These individuals faced unique potential limitations including a lack of relevant information regarding prescribed fire permits, smoke management, safety, and burning smaller parcels. These individuals also desired opportunities to retain land within their own families and also felt they were underrepresented within land management organizations and extension programs. In the future, policymakers' efforts may benefit from an intentional focus on building relationships with individual landowners, enhancing educational programming and access for landowners maintaining small and large parcels, and striving for diverse and inclusive representation within land management organizations. Master of Science During a period of time when the use of prescribed fire (i.e. intentionally ignited fires by land managers and professionals) has increased in the southeastern United States, African American non-industrial private landownership has decreased. When surveyed alongside white and Hispanic landowners within this region, African American private landowners expressed negative attitudes toward prescribed fire and responded at lower rates than others. The combined issues of land loss, minority representation, and the need for prescribed fire on private lands has generated questions about diversity and inclusion in landowner assistance and fire outreach programming. To address these issues, first-hand accounts were necessary to understand land management perspectives from African American private landowners within this region. Therefore, a research study was conducted to interview African American private landowners in southern Alabama, northern Florida, and southwestern Georgia. The objectives of this study were to determine what African Americans know about prescribed fire and if African American private landowners use prescribed fire for land management. Through personal interviews, African American landowners were asked to describe what influenced their use or lack of use of fire and what relationships they had formed with outreach and educational organizations. These individuals were also asked how they believed their prescribed fire perspectives and usage connected to their ancestral heritage. Twenty-one interviews were conducted and the results suggested that seventeen interviewees used prescribed fire at communal, historical, and organizational levels, but limitations to prescribed fire use did exist. Agency and organizational policymakers should focus on building relationships with individual landowners while offering better educational access that focuses on maintaining land legacies, particularly those that would be considered small parcels. Additionally, most of the landowners interviewed believed they were underrepresented within organizational leadership. There is indeed a cultural fabric that cannot be erased from current African American private landowners. Their practices and views are key to the inclusive and diverse conversations that should guide southeastern prescribed fire into the future.

From 2001&ndash, 2018, a series of fuel reduction and ecosystem restoration treatments were implemented in the southern Appalachian Mountains near Asheville, North Carolina, USA. Treatments consisted of prescribed fire (four burns), mechanical cutting of understory shrubs and mid-story trees (two cuttings), and a combination of both cutting and prescribed fire (two cuts + four burns). Soils were sampled in 2018 to determine potential treatment impacts for O horizon and mineral soil (0&ndash, 10 cm depth) carbon (C) and nitrogen (N) and mineral soil calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), and pH. Results suggested that mean changes in O horizon C and N and mineral soil C, N, C:N, Ca, and P from 2001&ndash, 2018 differed between the treatments, but only mineral soil C, N, C:N and Ca displayed differences between at least one fuel reduction treatment and the untreated control. One soils-related restoration objective was mineral soil N reduction and the cut + burn treatment best achieved this result. Increased organic matter recalcitrance was another priority, but this was not obtained with any treatment. When paired with previously reported fuels and vegetation results from this site, it appeared that continued use of the cut + burn treatment may best achieve long-term management objectives for this site and other locations being managed for similar long-term restoration and fuels management objectives.

Mechanical mastication is a fuels treatment that shreds midstorey trees and shrubs into a compacted woody fuel layer to abate fire hazards in fire-prone ecosystems. Increased surface fuel loading from mastication may, however, lead to undesirable fire intensity, long-duration flaming or smouldering, and undesirable residual tree mortality. Two major questions facing fuels managers are: how long do masticated fuels persist, and how does the composition of masticated fuelbeds change over time? To evaluate these changes, we measured 25 masticated sites with a range of vegetation, species masticated and time since treatment (1-16 years) in the western US. Seven of the 25 sites were sampled nearly a decade earlier, providing a unique opportunity to document fuelbed changes. Woody fuel loading ranged from 12.1 to 91.9 Mg ha(-1) across sites and was negatively related to time since treatment. At remeasured sites, woody fuel loads declined by 20%, with the greatest losses in 1- and 10-h woody fuels (69 and 33% reductions in mass respectively). Reductions were due to declines in number of particles and reduced specific gravity. Mastication treatments that generate greater proportions of smaller-diameter fuels may result in faster decomposition and potentially be more effective at mitigating fire hazard. USDAUnited States Department of Agriculture (USDA) [12-1-03-31]; USDI [12-1-03-31] An earlier draft of the manuscript benefitted from feedback provided by C. Copenheaver. We are grateful for the helpful comments from the three anonymous reviewers that helped improve this manuscript. This research was supported in part by funds provided by the USDA and the USDI Joint Fire Science Program (Project 12-1-03-31). Assistance with field data collection was provided by G. Hamby, C. Keller and J. Tobia. We appreciate the cooperation of the Sierra, Stanislaus, Tahoe, Lake Tahoe Basin Management Unit, Shasta-Trinity and Klamath National Forests as well as the Medford Bureau of Land Management office for assistance with selecting study sites and providing information about how treatments were implemented. J. Kane provided logistical support and numerous conversations through project development from which this study benefited. Public domain – authored by a U.S. government employee

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. Published version

Eastern deciduous forests in the United States have supplied marketable non-timber forest products (NTFP) since the 18th century. However, trade is still largely informal, and the market scope and structure are not well understood. One exception is American ginseng (Panax quinquefolius L.). Ginseng’s legal status as a threatened species requires that buyers apply for a license and keep sales records that are submitted to a state authority. Other marketable medicinal plants collected from the same forests, known colloquially as ‘off-roots’, are not similarly tracked. To study the characteristics of off-root trade in the eastern deciduous forests of the United States, registered ginseng buyers in 15 eastern states were surveyed in 2015 and 2016 about business attributes, purchase volume, and harvest distribution for 15 off-root species selected for their economic and conservation value. Buyers voluntarily reported harvesting 47 additional NTFP species. The most frequently purchased off-root species were the roots and rhizomes of two perennial understory plants: black cohosh (Actaea racemosa L.) and goldenseal (Hydrastis canadensis L.). Survey data were used to develop a buyer typology and describe the off-root market structure and material sourcing. The buyer typology included four distinct categories: side or specialty (small), seasonal venture (medium), large integrated or dedicated business (large), and dedicated bulk enterprise (regional aggregator). Market activity was mapped across the study area, demonstrating that most off-root trade is concentrated in central Appalachia, an area with extensive forests and a struggling economy. Study methods and data improve non-timber forest product market insights, are useful for forest management, and can support efforts to advance sustainable NTFP supply chains.

Fire affects the quantity and quality of soil organic matter (SOM). While combustion of the O-horizon causes direct losses of SOM, fire also transforms the remaining SOM into a spectrum of thermally altered organic matter. Pyrogenic carbon (PyC) can resist degradation and may have important effects on soil carbon cycling. The objectives of this study are to examine the mobility of PyC. Studying the effects of wildfire is challenging due to the rapid post-fire changes in the ecosystem and lack of robust controls. We overcame those limitations by examining the Chimney Tops 2 Fire which burned 4,617 ha of the Great Smoky Mountains National Park (GRSMNP), including a National Ecological Observatory Network (NEON) site, in November 2016. We examined PyC in soils from three time points from an area burned at low-severity (pre-, immediate post-, and 11 months post-fire) and two time points from areas burned at lower to higher severity (immediate post- and 11 months post-fire). At locations with pre-fire soil samples we found that PyC increased in the O-horizon (2.22 g BPCA/kg soil) after low severity fire, which resulted in higher PyC concentrations at 5-10 cm (0.73 g BPCA/kg soil and 17.79 g BPCA/kg C) and 10-20 cm (12.19 g BPCA/kg C) of depth in the mineral soil. Sites burned at higher severity had more PyC in the O horizon relative to sites burned at lower severity (10.29 g BPCA/kg soil and 29.89 g BPCA/kg C). As a result of higher concentrations of PyC in the O-horizons burned at higher severity, statistically more PyC moved from the O-horizon to the 0-10 cm horizon from immediate to 1-year post-fire (1.37 g BPCA/kg soil and 16.10 g BPCA/kg C). Lastly, the depth profile of C and BPCA suggest a shift in the source and amount of PyC in these soil profiles over time-possibly as a result of fire suppression. Results indicate that low severity fire may be an important mechanism by which PyC is produced and transported into mineral soils. National Science FoundationNational Science Foundation (NSF) [NSF-1733885, 1340504] This material was based upon work supported by the National Science Foundation under Grant Number NSF-1733885 and 1340504.

The volume, value and distribution of the nontimber forest product (NTFP) trade in the United States are largely unknown. This is due to the lack of systematic, periodic and comprehensive market tracking programs. Trade measurement and mapping would allow market actors and stakeholders to improve market conditions, manage NTFP resources, and increase the sustainable production of raw material. This is especially true in the heavily forested and mountainous regions of the eastern United States. This study hypothesized that the tendency to purchase medicinal NTFPs in this region can be predicted using socioeconomic and environmental variables associated with habitat and trade, and those same variables can be used to build more robust estimates of trade volume. American ginseng (Panax quinquefolius L.) dealers were surveyed (n = 700), because by law they must acquire a license to legally trade in this species, and therefore report a business address. They also record purchase data. Similar data are not reported for other medicinal species sold to the same buyers, known colloquially as &lsquo, off-roots&rsquo, Ginseng buyers were queried about trade activity in eleven commonly-harvested and previously untracked medicinal NTFP species in 15 states. Multinomial logistic regression comprised of socioeconomic and environmental predictors tied to business location was used to determine the probability that a respondent purchased off-roots. Significant predictors included location in a particular subregion, population and percentage of employment in related industries. These variables were used in a two-step cluster analysis to group respondents and nonrespondents. Modeled probabilities for off-root purchasing among respondents in each cluster were used to impute average off-root volumes for a proportion of nonrespondents in the same cluster. Respondent observations and nonrespondent estimations were summed and used to map off-root trade volume and value. Model functionality and estimates of the total volume, value and spatial distribution are discussed. The total value of the species surveyed to harvesters was 4.3 million USD. We also find that 77 percent of the trade value and 73 percent of the trade volume were represented by two species: black cohosh (Actaea racemosa L.) and goldenseal (Hydrastis canqdensis L.)

Urban tree canopy (UTC) assessment is essential for understanding the structure and function of urban forests and for devising management strategies. Geospatial techniques are routinely used for UTC assessment, yet their capabilities and limitations may not be apparent to urban forestry practitioners. This paper provides an overview of two primary methods of geospatial UTC assessment: photo interpretation (PI) and computerized image classification (IC). These methods were evaluated through a case study of an urbanized college campus in the eastern United States. The web-based application i-Tree Canopy is a PI method that uses statistical point sampling to estimate land cover. To examine the effect of point sample size on accuracy and certainty of the land cover estimates, we performed independently replicated assessments of our study area at various point sample sizes. We compared these findings with two IC methods: a proprietary analysis using high-spatial-resolution imagery and a low-spatial-resolution analysis using the web-based application i-Tree Landscape. With i-Tree Canopy, the estimate of UTC in our study area stabilized at a mean of 14.7% when point sample size reached 100 points, but it required more than 500 points to reach a tolerable standard error of less than 1.7%. By comparison, high-resolution imagery (considered the most robust form of assessment) estimated UTC in the study area at 16.1%, and i-Tree Landscape substantially underestimated UTC at 11.3%. Possible sources of variation in these estimates, along with practical considerations for choosing an appropriate UTC assessment method, are discussed. Published (Publication status)

In-stream watershed level evaluations confirm that application of recommended forestry best management practices (BMPs) can minimize sedimentation following management, while on-site erosion research shows that BMPs reduce erosion from individual forest operations, thus implying watershed-level sediment reductions. Assessments of forest operations and sediment have developed very few sediment delivery ratios (SDR). Linking BMP levels (low, standard recommendation, high) within specific forest operations to sedimentation could enable managers to evaluate BMP effects. Reported data regarding forest operations, erosion rates and SDR by forest operation, and BMP implementation levels were sufficient within the Piedmont region to allow approximations of sediment delivery and BMP efficiency. Existing United States Department of Agriculture (USDA) Forest Service reports and published erosion and sediment research were used to comprise the following method. For regional annual harvests, estimated sediment deliveries (Mg year&minus, 1) = annual harvest area (ha year&minus, 1) &times, weighted average erosion rate from all forest operations (Mg ha&minus, 1 year&minus, SDR (unitless ratio). Weighted average erosion rates for all forest operations were determined by applying areas in each operational activity (%) &times, estimated erosion per operation (Mg ha&minus, 1). In comparing published data, standard BMPs reduced estimated sedimentation by 75% compared to low BMP implementation levels. This supports forestry BMP efficiency findings reported for sediment removals in watershed studies. Higher levels of BMP implementation were estimated to potentially remove nearly all forest operation-produced sediment. Values of this pilot study should be viewed cautiously, as estimates were based on limited data, estimated operations, and limited SDRs, are based on BMP categories that vary between states, and address only one year following harvests. However, the approach provided approximations that facilitate BMP evaluations and can be improved with additional data. This methodology highlights the importance of accurate estimates of erosion rates, SDRs, sediment masses, and area for operations. This supports the importance of state programs, which have increased BMP implementation rates and compliance options with BMP program maturation.

Harvesting traffic may alter soil properties and reduce forest productivity if soil disturbances are not mitigated. Logging operations were conducted during high soil moisture conditions on the South Carolina, USA coast to salvage timber and reduce wildfire potential following Hurricane Hugo in 1989. Long term study sites were established on wet pine flats to evaluate effects of primary skid trails and site preparation on soil properties and loblolly pine productivity. The experiment was analyzed as a split-plot within an unbalanced randomized complete block design having 12 blocks, two levels of traffic (primary skid trail (On), no obvious traffic (Off)) and four levels of site preparation (bedding (Bed), disking with bedding (D/B), disking (Disk), no site preparation (None)). Remeasurement of the study was conducted in 2015 at 25 years after salvage logging (stand age 23 years). Bed and D/B treatments had greater saturated hydraulic conductivity (p = 0.0567) and macro porosity (p = 0.0071) and lower bulk density (p = 0.0226) values than Disk and None treatments. Macroporosity benefits were evident two years after site preparation installation, but bulk density and saturated hydraulic conductivity were not, suggesting these two measurements were affected over time by differences in rooting activity influenced by initial aeration benefits. Depth to iron depletion (p = 0.0055) was significantly greater and soil carbon (p < 0.0001) was significantly lower in Bed and D/B treatments due to bed elevation above the water table and improved drainage. This implies greater aeration for roots, but trade-offs in aboveground biomass and soil carbon storage. However, above and below ground carbon differences balanced one another between treatments so that combined carbon storage in soil and above ground loblolly pine biomass was not significantly different by site preparation treatment (p = 0.1127). Bed and D/B resulted in approximately double the stand biomass (p < 0.0001) and stand density (p < 0.0001) than Disk and None. Bed and D/B generally created more favorable soil properties and enhanced long term loblolly pine stand productivity. Differences in soil properties and stand productivity between traffic levels, with and without site preparation, were negligible suggesting natural soil recovery mechanisms were mitigated effects of wet site harvesting over 25 years. McIntire-Stennis Program of the National Institute of Food and Agriculture, USDA; National Council for Air and Stream Improvement Inc. (NCASI); USDA Forest Service Southern Research Station Santee Experimental Forest; Virginia Tech Forest Operations and Business Research Cooperative; Virginia Tech Department of Forest Resources and Environmental Conservation This research received financial and/or logistical support from the McIntire-Stennis Program of the National Institute of Food and Agriculture, USDA; the National Council for Air and Stream Improvement Inc. (NCASI); The USDA Forest Service Southern Research Station Santee Experimental Forest personnel; the Virginia Tech Forest Operations and Business Research Cooperative; and the Virginia Tech Department of Forest Resources and Environmental Conservation. Public domain – authored by a U.S. government employee

Ground based timber harvesting on wet sites has been linked to alteration of soil properties that may result in reduced long term site productivity. Following Hurricane Hugo in the fall of 1989, numerous salvage logging operations were conducted under high soil moisture conditions to reduce wildfire risk and salvage timber within the Francis Marion National Forest in the lower coastal plain of South Carolina. Study sites were established on wet pine flats to examine the long term effects of primary skid trails and site preparation on planted loblolly pine (Pinus taeda L.) growth. Treatment effects were analyzed as a split-plot within a randomized complete block design with 12 blocks, four levels of site preparation (none, disking, bedding, disking with bedding), and two levels of machine traffic (primary skid trail, no obvious traffic). After 23 years, bedding and disking with bedding enhanced stand density (p < 0.0001) and above ground stand biomass (p < 0.0001) relative to the disking and non-site prepared treatments. None of the site preparation treatments were effective at increasing biomass of individual trees. Mean height (p < 0.0001), DBH (p < 0.0001), and biomass of individual trees (p < 0.0001) were lower on primary skid trails than in non-trafficked areas. Traffic did not have a significant effect on stand density (p < 0.4662) or stand biomass (p = 0.1564). Selected soil physical properties and productivity measurements were similar for the non-site prepared treatment on and off primary skid trails, suggesting that 23 years is sufficient time for soils in wet flats to naturally recover from wet weather harvest disturbance. This study indicates that bedding may be the most efficient management practice to enhance long term stand productivity for loblolly pine on aeration-limited sites by increasing seedling survival. Minimizing the spatial extent of skid trails may increase growth of individual trees. (C) 2017 Elsevier B.V. All rights reserved. McIntire-Stennis Program of the National Institute of Food and Agriculture, USDA; National Council for Air and Stream Improvement Inc. (NCASI); USDA Forest Service Southern Research Station Santee Experimental Forest personnel; Virginia Tech Forest Operations and Business Research Cooperative; Virginia Tech Department of Forest Resources and Environmental Conservation This research received financial and/or logistical support from the McIntire-Stennis Program of the National Institute of Food and Agriculture, USDA; the National Council for Air and Stream Improvement Inc. (NCASI); The USDA Forest Service Southern Research Station Santee Experimental Forest personnel; the Virginia Tech Forest Operations and Business Research Cooperative; and the Virginia Tech Department of Forest Resources and Environmental Conservation. Public domain – authored by a U.S. government employee

As southern pine forests (both planted and naturally regenerated) are more heavily used to provide biomass for the developing energy sectors and carbon sequestration, a better understanding of models used to characterize regional biomass estimates is needed. We harvested loblolly pines (Pinus taeda L.) between 0.5 and 15 cm dbh from several plantations and naturally regenerated stands in southeastern Arkansas to evaluate allometric relationships based on stand origin. In this process, each pine was separated into stemwood, branches + foliage, and taproot biomass components. Although the differences changed with dbh, loblolly pines from planted stands generally had greater percentages of biomass allocated to foliage + branches and taproots, whereas those from natural-origin stands had greater amounts in stemwood, aboveground, and total biomass. National Biomass Estimator (NBE) high-specific gravity pine equations predicted natural-origin aboveground biomass reasonably well. However, the same NBE model underpredicted aboveground biomass for small (similar to 5 cm) diameter planted pine and overpredicted planted pines between 7 and 15 cm dbh. When scaled to stand-level estimates, the NBE models resulted in estimates for average stand diameters of 5, 10, and 15 cm that ranged from -18.6 to 2.1% for natural stands and from -21.9 to 62.8% for planted stands. Agriculture and Food Research Initiative Competitive Grant from the USDA National Institute of Food and Agriculture [2009-35103-05356]; Southern Research Station of the USDA Forest Service; Arkansas Forest Resources Center We thank the following individuals for their contributions: Kirby Sneed and Rick Stagg (USDA Forest Service); Jonathan Hartley (University of Arkansas-Monticello); and Conner Fristoe (Weyerhaeuser Company). This research was supported by Agriculture and Food Research Initiative Competitive Grant 2009-35103-05356 from the USDA National Institute of Food and Agriculture, the Southern Research Station of the USDA Forest Service, and the Arkansas Forest Resources Center. Public domain – authored by a U.S. government employee

Forest trees are an unparalleled group of organisms in their combined ecological, economic and societal importance. With widespread distributions, predominantly random mating systems and large population sizes, most tree species harbour extensive genetic variation both within and among populations. At the same time, demographic processes associated with Pleistocene climate oscillations and land-use change have affected contemporary range-wide diversity and may impinge on the potential for future adaptation. Understanding how these adaptive and neutral processes have shaped the genomes of trees species is therefore central to their management and conservation. As for many other taxa, the advent of high-throughput sequencing methods is expected to yield an understanding of the interplay between the genome and environment at a level of detail and depth not possible only a few years ago. An international conference entitled ‘Genomics and Forest Tree Genetics’ was held in May 2016, in Arcachon (France), and brought together forest geneticists with a wide range of research interests to disseminate recent efforts that leverage contemporary genomic tools to probe the population, quantitative and evolutionary genomics of trees. An important goal of the conference was to discuss how such data can be applied to both genome-enabled breeding and the conservation of forest genetic resources under land use and climate change. Here, we report discoveries presented at the meeting and discuss how the ecological genomic toolkit can be used to address both basic and applied questions in tree biology.

We examine the impact of measurement errors in geocoding of property locations and in the assessment of Mountain Pine Beetle-induced tree damage within the proximity of a given residence on estimated losses in home values. For our sample of homes in the wildland-urban interface of the Colorado front range and using a novel matching estimator with Bayesian regression adjustment we find that both types of errors can lead to substantial biases in estimated losses. Our results confirm that the Forest Service's Aerial Detection Survey is generally too coarse to be informative for property valuation that depends on highly localized spatial data. United States Forest Service, Southern Research StationUnited States Department of Agriculture (USDA)United States Forest Service [12-JV-11330143-106] Published version This work was supported by the United States Forest Service, Southern Research Station [cooperative agreement number 12-JV-11330143-106]. Public domain – authored by a U.S. government employee

Shelterbelts have been planted around the world for many reasons. Recently, due to increasing awareness of climate change risks, shelterbelt agroforestry systems have received special attention because of the environmental services they provide, including their greenhouse gas (GHG) mitigation potential. This paper aims to discuss shelterbelt history in Canada, and the environmental benefits they provide, focusing on carbon sequestration potential, above- and below-ground. Shelterbelt establishment in Canada dates back to more than a century ago, when their main use was protecting the soil, farm infrastructure and livestock from the elements. As minimal-and no-till systems have become more prevalent among agricultural producers, soil has been less exposed and less vulnerable to wind erosion, so the practice of planting and maintaining shelterbelts has declined in recent decades. In addition, as farm equipment has grown in size to meet the demands of larger landowners, shelterbelts are being removed to increase efficiency and machine maneuverability in the field. This trend of shelterbelt removal prevents shelterbelt’s climate change mitigation potential to be fully achieved. For example, in the last century, shelterbelts have sequestered 4.85 Tg C in Saskatchewan. To increase our understanding of carbon sequestration by shelterbelts, in 2013, the Government of Canada launched the Agricultural Greenhouse Gases Program (AGGP). In five years, 27 million dollars were spent supporting technologies and practices to mitigate GHG release on agricultural land, including understanding shelterbelt carbon sequestration and to encourage planting on farms. All these topics are further explained in this paper as an attempt to inform and promote shelterbelts as a climate change mitigation tool on agricultural lands. Published version

Watershed management practices such as prescribed fire, harvesting and understory mastication can alter the chemical composition and thickness of forest detritus, thus affecting the quantity and quality of riverine dissolved organic matter (DOM). Long-term effects of watershed management on DOM composition were examined through parallel field and extraction-based laboratory studies. The laboratory study was conducted using detritus samples collected from a pair of managed and unmanaged watersheds in South Carolina, USA. Results showed that dissolved organic carbon (DOC), total dissolved nitrogen (TDN) and ammonium (NH4+-N) concentrations were higher in water extracts from the unmanaged watershed than from the managed watershed (P < 0.01). Pyrolysis gas chromatography-mass spectrometry analysis showed that water extracts from the unmanaged watershed contained more aromatic compounds than extracts from the managed watershed. For the field study, monthly water samples were collected for 1 year (2015) from the paired watersheds. DOC and TDN concentrations, as well as DOM aromaticity, were significantly higher in the unmanaged watershed than in the managed watershed for most of the year (P < 0.05) and were linked to detrital thickness, precipitation and flow patterns. The formation potential of two regulated disinfection by-products was lower in the unmanaged watershed for most of 2015 (P < 0.05). From this study, it appears that long-term watershed management practices may alter detrital mass and chemistry in ways that improve water quality. Joint Fire Science Program [14-1-06-19]; USEPAUnited States Environmental Protection Agency [R835864]; USDA Forest Service National Fire Plan (2014-18) We are grateful for financial support from the Joint Fire Science Program (Project 14-1-06-19), USEPA (R835864) and the USDA Forest Service National Fire Plan (2014-18). We also thank Mary-Frances Wolf, Ryan Marsh, Rob O'Neal, David Miller, Jennie Untener and Brian Williams for their assistance with fieldwork and sample collection. Public domain – authored by a U.S. government employee

This study analyzed the perceptions of four stakeholder groups (forest landowners, private forest consultants, forest management researchers or educators, and federal or state agency foresters), regarding their management practices and preferred geographic growing conditions of loblolly pine in Virginia by combining AHP (analytical hierarchy process) and regression modeling. By ranking the importance of different geographical conditions for managing loblolly pine, we aimed to identify ways to support loblolly growth as a potential feedstock for biofuel generation. We achieved this through collecting survey responses from 43 stakeholders during the 2019 Virginia Forestry Summit. The results showed that the landowner, researcher/educator, and federal/state agency stakeholder groups all indicated that proximity to a mill was the most important criteria, whereas the consultant stakeholder group indicated that proximity to a road was the most important criteria. All the stakeholder groups indicated that distance from protected land was the least important criteria, followed by proximity to a water body and flat land. The regression model revealed that acres of land managed and loblolly rotation age were correlated to the weight given to the distance to a mill criterion, where increased acreage and increased rotation age were associated with an increased prioritization of proximity to a mill. Distance from protected land, the lowest-ranking criteria, was shown to have an association with the level of experience with loblolly, where more experience was associated with a lower prioritization of proximity from protected land. A contingency analysis of the self-identified level of experience with loblolly in each stakeholder group revealed that federal/state agency foresters had the most experience, followed by consultants, landowners, and researchers/educators. The research supports the importance of understanding the variation of perceptions between and within stakeholder groups in order to develop the necessary infrastructural and policy support for the sustainable development of bioenergy.

Traditional timber harvests on steep slopes have been conducted through labor-intensive and sometimes environmentally impactful methods, such as manual felling with chainsaws and extraction using bladed skid trails, winching, or cable yarding. Ground-based mechanized harvesting and primary transportation methods such as cut-to-length harvesters and forwarders have emerged in some parts of the world as low-impact, safe, and efficient alternatives to the aforementioned systems. However, when mechanized operations are used on steep terrain, problems such as poor stability, loss of traction, and increased soil disturbance can occur. Tethered or winch-assisted logging practices are being tested and applied in several countries to adapt to challenges associated with operating equipment on steep slopes while minimizing environmental impact. To better understand the feasibility of these systems, we conducted a designed experiment to quantify changes in soil properties and predicted erosion resulting from varying numbers of passes and payload levels by a forwarder operating on slopes ranging from 27 to 38 degrees. The machine was equipped with two different track configurations, tethered by either a machine-mounted or self-contained winch, in eucalyptus plantations in Brazil. On low slopes, bulk density significantly increased, but it did not increase on steeper slopes, this demonstrates traction winches&rsquo, effectiveness at reducing concentrated ground pressures. Rut depths were minimal and decreased with increasing slope classes due to reduced track slippage. Predicted erosion rates were high, primarily due to the extremely steep, long slopes and lack of adequate cover in some portions of the trail, illustrating the importance of proper erosion management practices on steep slopes.

Forest Productivity Cooperative Webinar

Estimating forest canopy height

Outside forests, Andhra Pradesh is greening, and we are learning by how much— and why. Our objectives are to (1) map smallholder forest plantations in Andhra Pradesh using multitemporal HLS S10 and/or very-high spatial resolution commercial satellite data, and (2) determine the drivers of plantation forest establishment. We have (1) developed a land use model that integrates land quality and spatial aspects of the farm with market variables and farmer production decisions, (2) implemented a household-level socio-economic survey, and (3) completed a Sentinel 2-era classification that separates natural from planted forest with 94% accuracy. Plantation forestry is rapidly expanding in Asia, and understanding the extent, drivers, and ramifications of these new trees outside forests is vital.

Sustainable forest management is hugely dependent on high-quality estimates of forest site productivity, but it is challenging to generate productivity maps over large areas. We present a method for generating site index (a measure of such forest productivity) maps for plantation loblolly pine (Pinus taeda L.) forests over large areas in the southeastern United States by combining airborne laser scanning (ALS) data from disparate acquisitions and Landsat-based estimates of forest age. For predicting canopy heights, a linear regression model was developed using ALS data and field measurements from the Forest Inventory and Analysis (FIA) program of the US Forest Service (n = 211 plots). The model was strong (R2 = 0.84, RMSE = 1.85 m), and applicable over a large area (~208,000 sq. km). To estimate the site index, we combined the ALS estimated heights with Landsat-derived maps of stand age and planted pine area. The estimated bias was low (&minus, 0.28 m) and the RMSE (3.8 m, relative RMSE: 19.7%, base age 25 years) was consistent with other similar approaches. Due to Landsat-related constraints, our methodology is valid only for relatively young pine plantations established after 1984. We generated 30 m resolution site index maps over a large area (~832 sq. km). The site index distribution had a median value of 19.4 m, the 5th percentile value of 13.0 m and the 95th percentile value of 23.3 m. Further, using a watershed level analysis, we ranked these regions by their estimated productivity. These results demonstrate the potential and value of remote sensing based large-area site index maps.

Leaf area index (LAI) is an important biophysical parameter used to monitor, model, and manage loblolly pine plantations across the southeastern United States. Landsat provides forest scientists and managers the ability to obtain accurate and timely LAI estimates. The objective of this study was to investigate the relationship between loblolly pine LAI measured in situ (at both leaf area minimum and maximum through two growing seasons at two geographically disparate study areas) and vegetation indices calculated using data from Landsat 7 (ETM+) and Landsat 8 (OLI). Sub-objectives included examination of the impact of georegistration accuracy, comparison of top-of-atmosphere and surface reflectance, development of a new empirical model for the species and region, and comparison of the new empirical model with the current operational standard. Permanent plots for the collection of ground LAI measurements were established at two locations near Appomattox, Virginia and Tuscaloosa, Alabama in 2013 and 2014, respectively. Each plot is thirty by thirty meters in size and is located at least thirty meters from a stand boundary. Plot LAI measurements were collected twice a year using the LI-COR LAI-2200 Plant Canopy Analyzer. Ground measurements were used as dependent variables in ordinary least squares regressions with ETM+ and OLI-derived vegetation indices. We conclude that accurately-located ground LAI estimates at minimum and maximum LAI in loblolly pine stands can be combined and modeled with Landsat-derived vegetation indices using surface reflectance, particularly simple ratio (SR) and normalized difference moisture index (NDMI), across sites and sensors. The best resulting model (LAI = &minus, 0.00212 + 0.3329SR) appears not to saturate through an LAI of 5 and is an improvement over the current operational standard for loblolly pine monitoring, modeling, and management in this ecologically and economically important region.

Smouldering fire vulnerability in organic-rich, wetland soils is regulated by hydrologic regimes over short (by antecedent wetness) and long (through influences on soil properties) timescales. An integrative understanding of these controls is needed to inform fire predictions and hydrologic management to reduce fire vulnerability. The Great Dismal Swamp, a drained peatland (Virginia and North Carolina, USA), recently experienced large wildfires, motivating hydrologic restoration efforts. To inform those efforts, we combined continuous water levels, soil properties, moisture holding capacity and smouldering probability at four sites along a hydrologic gradient. For each site, we estimated gravimetric soil moisture content associated with a 50% smouldering probability (soil moisture smoulder threshold) and the water tension required to create this moisture threshold (tension smoulder threshold). Soil properties influenced both thresholds. Soils with lower bulk density smouldered at higher moisture content but also had higher moisture holding capacity, indicating that higher tensions (e.g. deeper water tables) are required to reach smouldering thresholds. By combining thresholds with water level data, we assessed smouldering vulnerability over time, providing a framework to guide fire prediction and hydrologic restoration. This work is among the first to integrate soil moisture thresholds, moisture holding capacities and water level dynamics to explore spatiotemporal variation in smouldering fire vulnerability. Virginia Tech Department of Forest Resources and Environmental Conservation; National Fire Plan; National Socio-Environmental Synthesis Center; National Science Foundation [DBI-1052875] This work was funded by the Virginia Tech Department of Forest Resources and Environmental Conservation. J. M. Varner was supported by funds from the National Fire Plan. C. N. Jones was supported by the National Socio-Environmental Synthesis Center under funding received from the National Science Foundation (grant number DBI-1052875).

The US National Greenhouse Gas Inventory uses the component ratio method (CRM), a volume conversion approach that incorporates models for tree biomass components, for forest carbon assessments. However, the performance of the CRM relative to other methods, as well as influences on its accuracy and precision, must be evaluated. We constructed a data-driven CRM (n-CRM), used it to predict total tree and component biomass for six US tree species, and compared this approach to a reference allometric model. We also assessed the influence of size, crown dynamics, and stem growth on the performance of both methods. Results show that the n-CRM was more accurate for four species, resulting from the inclusion of more predictor variables. Both methods had high uncertainty, but the precision of n-CRM predictions was two to eight times higher for small diameter trees (< 10 cm) across all species. Accuracy and precision of the crown component models (i. e. branches and foliage) was low, though better for pines than for hardwoods. Species-level analysis suggests that poor precision is influenced by crown traits and the size distribution of fitting datasets. Our results highlight needed improvements to the n-CRM, and motivate further development of data that facilitate predictive evaluation of biomass models. USDA Forest Service Forest Inventory and Analysis Program, Northern Region; Minnesota Agricultural Experiment Station; Michigan AgBioResearch through the USDA National Institute of Food and Agriculture Data compilation for the legacy data and the independent validation datasets, as well as B. Clough's time, were funded by the USDA Forest Service Forest Inventory and Analysis Program, Northern Region. Additional funding and support was available from the Minnesota Agricultural Experiment Station. Part of D.W. MacFarlane's time was supported with funds from Michigan AgBioResearch through the USDA National Institute of Food and Agriculture. Public domain – authored by a U.S. government employee

Recent studies suggest increased fire frequency may impair soil chemistry, but few studies have examined long-term effects of repeated, frequent prescribed fires on forest soil properties in the southeastern Coastal Plain, USA. In this study, forest soil chemistry at the 0&ndash, 10 and 10&ndash, 20 cm mineral soil depths of sandy surface horizons (Entisols and Spodosols) were compared among units burned 0, 4, 6, and 8 times between 2004 and 2015 and 0 and 20 times between 1978 and 2015 in a longleaf (Pinus palustris Mill.)&ndash, loblolly (Pinus taeda L.) pine savanna at the Tom Yawkey Wildlife Center (Georgetown, SC, USA). At the 0&ndash, 10 cm soil depth, soil pH (p = 0.00), sulfur (p = 0.01), calcium (p = 0.01), iron (p &lt, 0.01), manganese (p &lt, 0.01), and aluminum (p = 0.02) treatment means differed (2004&ndash, 2015). Calcium and manganese displayed positive, significant relationships and sulfur displayed a negative, significant relationship with increasing fire frequency (p &lt, 0.05). However, correlation of these relationships was low (r2 &le, 0.23). Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the mean of the unburned compartment, sulfur (p = 0.01) and iron (p &lt, 0.01) were less in soils from the burned compartments. At the 10&ndash, 20 cm soil depth, soil pH (p = 0.01), manganese (p = 0.04), phosphorus (p = 0.01), potassium (p = 0.02), and iron (p &lt, 0.01) treatment means differed (2004&ndash, 2015). Potassium displayed a negative, significant relationship and soil pH displayed a positive, significant relationship with increasing fire frequency (p &lt, 0.05). Correlation of these relationships was low (r2 &le, 0.16), however. Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the unburned compartment, potassium (p = 0.00) and iron (p &lt, 0.01) were less in soils from burned compartments. These results are inconsistent with studies suggesting that forest soil chemistry is substantially altered by increased fire frequency and support other studies from this region that have documented minimal or temporary soil chemical changes associated with frequent prescribed fires.

Forest ecosystems play multiple important roles in meeting the habitat needs of different organisms and providing a variety of services to humans. Biodiversity is one of the structural features in dynamic and complex forest ecosystems. One of the most challenging issues in assessing forest ecosystems is understanding the relationship between biodiversity and environmental factors. The aim of this study was to investigate the effect of biotic and abiotic factors on tree diversity of Hyrcanian forests in northern Iran. For this purpose, we analyzed tree diversity in 8 forest sites in different locations from east to west of the Caspian Sea. 15,988 trees were measured in 655 circular permanent sample plots (0.1 ha). A combination of machine learning methods was used for modeling and investigating the relationship between tree diversity and biotic and abiotic factors. Machine learning models included generalized additive models (GAMs), support vector machine (SVM), random forest (RF) and K-nearest–neighbor (KNN). To determine the most important factors related to tree diversity we used from variables such as the average diameter at breast height (DBH) in the plot, basal area in largest trees (BAL), basal area (BA), number of trees per hectare, tree species, slope, aspect and elevation. A comparison of RMSEs, relative RMSEs, and the coefficients of determination of the different methods, showed that the random forest (RF) method resulted in the best models among all those tested. Based on the results of the RF method, elevation, BA and BAL were recognized as the most influential factors defining variation of tree diversity. Published version

Scotch broom (Cytisus scoparius (L.) Link) is a highly competitive, nonnative, leguminous shrub species of major concern in coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) forests of the Pacific Northwest that has potential to impact long-term soil productivity. We conducted a bioassay to assess the potential for legacy effects on soils (e.g., soil nutrient effects, soil seedbank, etc.) following Scotch broom removal and the potential for recovery over time. The bioassay was conducted using glacial-outwash soils from an existing Long-Term Soil Productivity study near Matlock, WA, USA, where Scotch broom had been removed or kept out for 0 (broom present), 4, 10, or 14 years. Soils from each broom removal duration were combined with fertilizer treatments to assess mechanisms of response of three native plant species: yarrow (Achillea millefolium L.), Roemer's fescue (Festuca idahoensis Elmer ssp. Roemeri), and coast Douglas-fir. There was evidence for negative soil legacy effects on Douglas-fir growth and biomass, which decreased with time since broom removal. Responses to the fertilizer treatments indicated the effect was not associated with reduced nutrient availability. In contrast, both yarrow and Roemer's fescue had significantly greater biomass in soil from where broom was recently present, which decreased with time since broom removal. Responses to the fertilizer treatments indicated that this positive legacy effect is associated with nutrient availability, likely increased N. Soils from 0 and 4 years since broom removal were estimated as having the potential to produce over 578,500 Scotch broom germinants ha(-1) . Our results demonstrate the potential for both negative and positive soil legacy effects of broom depending on the responding plant species. Combined effects of negative soil legacies and a large and viable seed bank from Scotch broom create growing conditions likely to hinder long-term productivity of Douglas-fir. USDA National Institute for Food and Agriculture [GRANT11325729] Financial support for this research was provided by the USDA National Institute for Food and Agriculture (Grants.gov number: GRANT11325729). We thank Green Diamond Resource Company for use of their land and logistical support. Thanks also to Dave Peter and James Dollins for assistance with the field and greenhouse work. Public domain – authored by a U.S. government employee

Accurate estimation of forest biomass and carbon stocks at regional to national scales is a key requirement in determining terrestrial carbon sources and sinks on United States (US) forest lands. To that end, comprehensive assessment and testing of alternative volume and biomass models were conducted for individual tree models employed in the component ratio method (CRM) currently used in the US' National Greenhouse Gas Inventory. The CRM applies species-specific stem volume equations along with specific gravity conversions and component expansion factors to ensure consistency between predicted stem volumes and weights, and additivity of predicted live tree component weights to match aboveground biomass (AGB). Data from over 76 600 stem volumes and 6600 AGB observations were compiled from individual studies conducted in the past 115 years - what we refer to as legacy data - to perform the assessment. Scenarios formulated to incrementally replace constituent equations in the CRM with models fitted to legacy data were tested using cross-validation methods, and estimates of AGB were scaled using forest inventory data to compare across 33 states in the eastern US. Modifications all indicated that the CRM in its present formulation underestimates AGB in eastern forests, with the range of underestimation ranging from 6.2 to 17 per cent. Cross-validation results indicated the greatest reductions in estimation bias and root-mean squared error could be achieved by scenarios that replaced stem volume, sapling AGB, and component ratio equations in the CRM. A change in the definitions used in apportioning biomass to aboveground components was also shown to increase prediction accuracy. Adopting modifications tested here would increase AGB estimates for the eastern US by 15 per cent, accounting for 1.5 Pg of C currently unaccounted for in live tree aboveground forest C stock assessments. Expansion of the legacy data set currently underway should be useful for further testing, such as whether similar gains in accuracy can be achieved in estimates of regional or national-scale C sequestration rates. U.S. Department of Agriculture Forest Service, Forest Inventory and Analysis National Program; U.S. Department of Agriculture National Institute of Food and Agriculture, McIntire-Stennis Cooperative Forestry Program The U.S. Department of Agriculture Forest Service, Forest Inventory and Analysis National Program, and the U.S. Department of Agriculture National Institute of Food and Agriculture, McIntire-Stennis Cooperative Forestry Program. Public domain – authored by a U.S. government employee

Intensive management practices are commonly used to increase fiber production from forests, but potential tradeoffs with maintenance of long-term productivity and early successional biodiversity have yet to be quantified. We assessed soil and vegetation responses in replicated manipulations of logging debris (LD; either retained or removed) and competing vegetation control (VC; either initial or sustained annually for 5 years) for 10 years at two Douglas-fir sites that contrasted strongly in availability of soil nutrients and water. We evaluated (1) survival and growth of Douglas-fir to determine short-term effectiveness for fiber production, (2) change in soil C and nutrient pools as an indicator of longer-term effects of treatments on soil quality and ecosystem production, and (3) vegetation composition and cover for treatment effects on early successional biodiversity. Annual VC caused large increases in Douglas-fir growth at both sites, but increased survival only at the lower-productivity site. In most instances and regardless of site or treatment, soil C and nutrient pools increased following harvesting, but the increases were generally larger with lower intensity practices (LD retained and initial VC). Effects of LD were small and inconsistent at the higher productivity site, but LD retained increased Douglas-fir survival and growth and soil nutrient pools at the lower productivity site. Species diversity was reduced at both sites with annual VC because of increased Douglas-fir cover, but the magnitude was greater and the timing was earlier at the higher quality site where plant communities in all treatments had converged by year 10. Annual VC can be used to increase growth of planted Douglas-fir while maintaining soil nutrient pools for sustained ecosystem productivity, but a concurrent decrease in early successional diversity will occur with impacts increasing with site quality. Logging debris retention can have positive benefits to Douglas fir growth and soil nutrient pools, particularly at lower quality sites. Our results demonstrate a need for careful consideration of site quality to ensure that objectives are realized with regards to fiber production and maintenance of soil productivity and biodiversity with intensive forest management. USDA Forest Service Pacific Northwest Research StationUnited States Department of Agriculture (USDA)United States Forest Service; Port Blakely Tree Farms LLC; Virginia Tech; Green Diamond Resource Company; Randall Greggs; Mike Warjone This is a product of the Sustainable Forestry component of Agenda 2020, a joint effort of the USDA Forest Service Research and Development and the American Forest and Paper Association. Funds were provided by the USDA Forest Service Pacific Northwest Research Station, Virginia Tech, Green Diamond Resource Company, and Port Blakely Tree Farms LLC. The authors are especially grateful to Randall Greggs and Mike Warjone for providing critical financial and logistical support that made this study possible. Special thanks to J. Dollins, D. Stephens, B. Korman, D. Livada, and W. Devine for assisting with field and laboratory measurements. Public domain – authored by a U.S. government employee

The 2007 Angora Fire served as a stark reminder of the need for fuel reduction treatments in the Lake Tahoe Basin, California-Nevada, USA. Concerns exist, however, that the corresponding removal of forest floor fuels could increase erosion rates, negatively affecting the clarity of Lake Tahoe. To quantify trade-offs between fuel reduction and erosion, we conducted field-based snowmelt runoff simulation experiments at 16 sites within the Lake Tahoe Basin that had received mechanical mastication or prescribed fire treatments. Erodibility was measured to determine if thresholds of litter, duff, and woody fuel cover could be established that are sufficient for trapping sediment and increasing infiltration, without contributing to fire hazard. Field snow-melt simulations revealed that as little as 25% of the ground surface covered with masticated fuels over duff was sufficient to mitigate erosion. The post-prescribed fire environment characterized by heterogeneous patches of exposed bare mineral soil interspersed with unburned patches mitigated erosion by increasing infiltration. Considerable increases in sediment yield were observed in plots with >35% of ground area burned; the highest total sediment yields (values) occurred in plots where between 66% and 100% of the soil surface burned. Our field results suggest that erosion and wildfire severity can be simultaneously mitigated through the use of masticated fuel reduction treatments or prescribed fire treatments that leave sufficient organic matter to trap sediment but have sufficiently low fuel loading and/or enough fuel discontinuity or patchiness to limit fire spread. (C) 2015 Elsevier B.V. All rights reserved. Bureau of Land Management; USDA Forest Service Pacific Southwest Research StationUnited States Department of Agriculture (USDA)United States Forest Service Funding for this research was provided by the Bureau of Land Management through the sale of public lands as authorized by the Southern Nevada Public Land Management Act (SNLPMA). This Round 8 SNLPMA research grant was supported by an agreement with the USDA Forest Service Pacific Southwest Research Station. We appreciate the help of A. Geritz, N. Schroeter, E. Banwell, A. Heck, R. Arst-McCullough, M.E. Grismer and M. Hogan. We thank J. Baldwin for statistical assistance and J.L. Beyers for her review of the manuscript. Public domain – authored by a U.S. government employee

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&ndash, 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.

14 Pags.- 11 Figs., We present an analysis of the sensitivity of three key crops (alfalfa, barley and winter wheat) produced in the northwestern United States to climatic and agricultural market anomalies using widely used standardized indices. Rather than investigating sensitivity of crop yields (production per unit area), we focus on agricultural production (yield * harvested area) anomalies, which captures both variations in yield and the effect of decision-making factors such as allocation of cropping area. We used two well-known standardized precipitation and reference evapotranspiration (ETo) indices (SPI and EDDI, respectively) and a standardized crop value index in a multivariate linear regression analysis to determine the characteristic timing and time-scales of precipitation and ETo anomalies that best explain annual crop production anomalies. Since climatic and market factors are standardized, regression coefficients are interpreted as a sensitivity measure that captures the relative effect of climatic and agricultural markets on agricultural production. Results show that alfalfa production was most sensitive climatic anomalies while barley and wheat production was more responsive to crop prices. Sensitivity to precipitation anomalies followed gradients in precipitation, temperature, and soil moisture regimes across the study area where drier and warmer climates were associated with increased sensitivity to climatic anomalies. We found that irrigation decoupled alfalfa production from climatic variability, but the effect of irrigation on decoupling barley production was less clear. Winter wheat production was most sensitive to price anomalies, and alfalfa was least sensitive. Omitting agricultural market conditions and other farmer incentives may introduce biases in our understanding of how drought and climate change impact agricultural production., This work has been supported by the United States Department of Agriculture, USDA-NIFA research grant 2016-67026-25067, and by the NASA EPSCoR program research grant 80NSSC18M0025. P.W. also acknowledges partial support from the NSF EPSCoR cooperative agreement EPS-1101342.

Scotch broom (Cytisus scoparius (L.) Link) is an invasive, N-fixing shrub in recently harvested Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) forests in the Pacific Northwest. The ability of Scotch broom to dominate a site and displace Douglas-fir in this region may be mediated by site quality and site resource supply. Individual seedlings of Scotch broom (n = 46) and Douglas-fir (n = 46) were planted in a controlled nursery setting and monitored over two years to test the effects of irrigation and fertilization treatments on the physiology and growth of these oft-conflicting species. Overall, Scotch broom remained largely unaffected by resource availability relative to Douglas-fir, which was more sensitive to water and nutrient availability. Scotch broom consistently showed greater assimilation and transpiration rates and plant water potentials than Douglas-fir under all treatments - indicating an elevated ability to acquire soil water resources. The conservative ecology of Douglas-fir resulted in greater water-use efficiency than Scotch broom throughout the experiment, however. Similarly, Douglas-fir crown and height growth started later in the growing season and ended earlier than that of Scotch broom, indicating a longer growing season for Scotch broom but also the importance of resource availability early in the growing season for Douglas-fir given its determinate growth. While Douglas-fir growth reflected the additive effects of increased resource availability, it did not surpass the growth of Scotch broom, which maintained steady growth and biomass accrual under all treatment conditions. The height of Douglas-fir growing under optimized conditions was approximately 40 cm less than that of Scotch broom regardless of treatment regime by the end of the two-year study. This demonstrates how critical early intervention is for land managers in order to control this invasive to avoid Scotch broom overtopping Douglas-fir seedlings during stand establishment. Washington State Department of Natural Resources; U.S.D.A. National Institute for Food and Agriculture [GRANT11325729] We would like to thank the Washington State Department of Natural Resources, Webster Forest Nursery for allowing us to use their facilities to conduct this experiment, with special appreciation for the assistance of John Trobaugh, Eric Jefts, and Viviana Olivares. We would also like to thank Dave Peter, James Dollins, and Alyssa Peter for their help setting up and maintaining this study, as well as, taking field measurements. Funding for this project was provided by the U.S.D.A. National Institute for Food and Agriculture (Grants.gov number: GRANT11325729). Public domain – authored by a U.S. government employee