Browsing by Author "Cook, Rachel L."

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    Assessing the utility of NAIP digital aerial photogrammetric point clouds for estimating canopy height of managed loblolly pine plantations in the southeastern United States
    Ritz, Alison L.; Thomas, Valerie A.; Wynne, Randolph H.; Green, P. Corey; Schroeder, Todd A.; Albaugh, Timothy J.; Burkhart, Harold E.; Carter, David R.; Cook, Rachel L.; Campoe, Otavio C.; Rubilar, Rafael A.; Rakestraw, Jim (Elsevier, 2022-09)
    Remote sensing offers many advantages to supplement traditional, ground-based forest measurements, such as limiting time in the field and fast spatial coverage. Data from airborne laser scanning (lidar) have provided accurate estimates of forest height, where, and when available. However, lidar is expensive to collect, and wall-to-wall coverage in the United States is lacking. Recent studies have investigated whether point clouds derived from digital aerial photogrammetry (DAP) can supplement lidar data for estimating forest height due to DAP's lower costs and more frequent acquisitions. We estimated forest heights using point clouds derived from the National Agricultural Imagery Program (NAIP) DAP program in the United States to create a predicted height map for managed loblolly pine stands. For 534 plots in Virginia and North Carolina, with stand age ranging from 1 year to 42 years old, field-collected canopy heights were regressed against the 90th percentile of heights derived from NAIP point clouds. Model performance was good, with an R2 of 0.93 and an RMSE of 1.44 m. However, heights in recent heavily thinned stands were consistently underestimated, likely due to between-row shadowing leading to a poor photogrammetric solution. The model was applied to non-thinned evergreen areas in Virginia, North Carolina, and Tennessee to produce a multi-state 5 m x 5 m canopy height map. NAIP-derived point clouds are a viable means of predicting canopy height in southern pine stands that have not been thinned recently.
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    Biomass and nutrient mass of Acacia dealbata and Eucalyptus globulus bioenergy plantations
    Albaugh, Timothy J.; Rubilar, Rafael A.; Maier, Christopher A.; Acuna, Eduardo A.; Cook, Rachel L. (2017-02)
    We quantified biomass and nutrient accumulation of Acacia dealbata Link and Eucalyptus globulus Labill. planted at stem densities of 5000 and 15000 ha(-1) in a bioenergy plantation in Chile. We tested the hypotheses that species and stocking will not affect biomass or nutrient accumulation. Species and stocking did not affect biomass accumulation after five years; however, species and stocking did influence nutrient mass. A. dealbata had higher nitrogen mass than E. globulus for total (397 kg ha(-1) more, i.e., 126% higher), foliage (188 kg ha(-1), 218%), branch (55 kg ha(-1), 95%), stem (120 kg ha(-1), 86%), and root (34 kg ha (-1), 109%) components, likely because A. dealbata fixes nitrogen. A. dealbata had lower calcium mass than E. globulus for branch (111 kg ha(-1), 60%) and stem (69 kg ha(-1), 39%) components. Root nitrogen and phosphorus masses and foliage, branch and root boron masses were significantly lower with a stocking density of 5000 ha(-1). Low stocking produced the same amount of total biomass as high stocking for both species and would be less expensive to plant. A. dealbata had higher nitrogen mass and likely increased soil nitrogen. E. globulus had high calcium mass in the stem and branches; off-site losses could be mitigated with stem-only harvests and debarking of stems in the field. Given the rainfall patterns and water availability constraints in Chile, additional criteria including water use efficiency would be required to determine the best species for bioenergy plantations in Chile. (C) 2017 Elsevier Ltd. All rights reserved.
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    A common garden experiment examining light use efficiency and heat sum to explain growth differences in native and exotic Pinus taeda
    Albaugh, Timothy J.; Fox, Thomas R.; Maier, Christopher A.; Campoe, Otavio C.; Rubilar, Rafael A.; Cook, Rachel L.; Raymond, Jay E.; Alvares, Clayton A.; Stape, Jose L. (2018-10-01)
    Previous work indicates that Pinus taeda L. grows faster and has a higher carrying capacity when grown outside its native range. We were interested in examining the hypotheses that growth, light use efficiency (volume growth and absorbed photosynthetically active radiation relationship, LUE) and volume growth per unit heat sum is the same for native and exotic plantations. To test these hypotheses, we installed a common garden experiment where the same six genetic entries of P. taeda (four clonal varieties, one open pollinated family and one control mass pollinated family) were planted at three densities (618, 1235, and 1853 stems ha(-1)) with three or four replications at three sites (Virginia (VA), and North Carolina (NC) in the United States and Parana State in Brazil (BR)). The VA and BR sites were outside the native range of P. taeda. After five years of growth, the BR site had larger trees and stand scale basal area and volume were increasing faster than the other sites. Site did not affect LUE but density and genetic entry did. The sites were at different latitudes but the average photosynthetically active radiation at the top of the canopy was similar for the years when all sites were operational, likely because the BR site receives more rain annually and the cloudiness associated with the rain may have reduced available light. We estimated an hourly heat sum where the daytime temperature was between 5 and 38 degrees C, hours where vapor pressure deficit exceeded 1.5 kPa and days following nights where nighttime temperatures were less than 0 degrees C were excluded. Site was significant for the cumulative volume and heat sum relationship, for a given level of cumulative degree hours the sites ranked BR > VA > NC in cumulative volume. The different growth per unit of degree hours for each site indicated that something other than the heat sum was causing the observed difference in growth. Other factors including respiration and extreme climatic conditions may contribute to growth differences per unit degree hour and including these differences in the analysis would require a more detailed modeling effort to examine. The sites used in this study are ideally suited to continue testing additional hypotheses to explain the different growth between native and exotic P. taeda plantations because they have the same genotypes at all sites and consequently eliminate differences in genetics as a potential explanation for observed growth differences.
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    Complementarity increases production in genetic mixture of loblolly pine (Pinus taeda L.) throughout planted range
    Carter, David R.; Albaugh, Timothy J.; Camo, Otávio C.; Grossman, Jake J.; Rubilar, Rafael A.; Sumnall, Matthew; Maier, Christopher A.; Cook, Rachel L.; Fox, Thomas R. (ESA, 2020-09-01)
    Increased genotypic diversity has been associated with increased biomass production in shortrotation tree species. Increasing the genotypic diversity of loblolly pine (Pinus taeda L.) in an attempt to increase productivity has not been extensively studied nor tested operationally or over long durations (i.e., >7 yr). We used genetically mixed and pure rows of loblolly pine growing throughout its planted range— Virginia, North Carolina, and Brazil—to test the effects of genetic mixing on volume production. There were no significant effects of mixing rows compared to pure rows on uniformity or mortality. Under intensive silviculture, individual trees planted in mixed rows had approximately 7% greater volume than those in the pure rows (estimate = 0.015 m³/tree ± 0.006) in the final year of measurement—year 8 for Brazil and year 10 for North Carolina and Virginia. Scaling the increase in individual stem volume under mixed rows and intensive silviculture to 1235 stems ha⁻¹ would equate to an additional 1.85 m³∙ha⁻¹∙yr⁻¹ in mean annual increment. Measuring the net biodiversity effect, our data suggest the positive growth response is driven by complementarity and not selection, meaning both genetic entries tend to grow larger when grown together. Additional trials are necessary to test the effects of mixing rows across large plots and to assess whether this increase is sustained throughout the rotation. If this increasing trend were to hold for intensively managed plantations, strategically mixing rows to increase productivity could be a valuable addition to an intensively managed plantation requiring relatively little added operational consideration to implement.
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    Crown architecture, crown leaf area distribution, and individual tree growth efficiency vary across site, genetic entry, and planting density
    Albaugh, Timothy J.; Maier, Christopher A.; Campoe, Otavio C.; Yanez, Marco A.; Carbaugh, Eric D.; Carter, David R.; Cook, Rachel L.; Rubilar, Rafael A.; Fox, Thomas R. (2020-02)
    We examined crown architecture and within crown leaf area distribution effects on Pinus taeda L. growth in North Carolina (NC), Virginia (VA), and Brazil (BR) to better understand why P. taeda can grow much better in Brazil than in the southeastern United States. The NC, VA, and BR sites were planted in 2009, 2009, and 2011, respectively. At all sites, we planted the same two genetic entries at 618, 1236, and 1854 trees ha(-1). In 2013, when trees were still open grown, the VA and NC sites had greater branch diameter (24%), branch number (14%), live crown length (44%), foliage mass (82%), and branch mass (91%), than the BR site. However, in 2017, after crown closure and when there was no significant difference in tree size, site did not significantly affect these crown variables. In 2013, site significantly affected absolute leaf area distribution, likely due to differences in live crown length and leaf area, such that there was more foliage at a given level in the crown at the VA and NC sites than at the BR site. In 2017, site was still a significant factor explaining leaf area distribution, although at this point, with crown closure and similar sized trees, there was more foliage at the BR site at a given level in the crown compared to the VA and NC sites. In 2013 and 2017, when including site, genetic entry, stand density, and leaf area distribution parameters as independent variables, site significantly affected individual tree growth efficiency, indicating that something other than leaf area distribution was influencing the site effect. Better BR P. taeda growth is likely due to a combination of factors, including leaf area distribution, crown architecture, and other factors that have been identified as influencing the site effect (heat sum), indicating that future work should include a modeling analysis to examine all known contributing factors.
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    Effects of establishment fertilization on Landsat-assessed leaf area development of loblolly pine stands
    House, Matthew N.; Wynne, Randolph H.; Thomas, Valerie A.; Cook, Rachel L.; Carter, David R.; Van Mullekom, Jennifer H.; Rakestraw, Jim; Schroeder, Todd A. (Elsevier, 2024-03-15)
    Loblolly pine (Pinus taeda L.) plantations in the southeastern United States are among the world's most intensively managed forest plantations. Under intensive management, a common practice is fertilizing at establishment. The objective of this study was to investigate the effect of establishment fertilization on leaf area development of loblolly pine plantation stands (n = 3997) over 16 years compared to stands that did not receive nutrient additions at planting. Leaf area index (LAI) is a meaningful biophysical indicator of vigor and an important functional and structural element of a planted stand. The study area was stratified by plant hardiness zone to account for climatic differences and soil type (texture and drainage class), using the Cooperative Research in Forest Fertilization (CRIFF) groupings. LAI was estimated from Landsat imagery to create trajectories of mean stand LAI over 16 years. Establishment fertilization, on average, (1) increased stand LAI beginning at year two, with a peak at years six and seven, and (2) decreased the time required for a stand to reach a winter LAI of 1.5 by almost two years. Fertilization responses varied by climate zone and soil drainage class, where the warmest zones benefited the most, particularly in poorly drained soils. Past year 10, the differences in LAI between fertilized and unfertilized stands were not practically important. Using Landsat data in a cloud-computing environment, we demonstrated the benefits of establishment fertilization to stand LAI development using a large sample over the native range of loblolly pine.
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    Loblolly Pine Growth and Competition Response to Varied Chemical Site Preparation Treatments 14 Years After Establishment in the Piedmont of Virginia
    Byers, Alexander M. (Virginia Tech, 2021-06-16)
    Chemical site preparation is used to enhance the productivity of loblolly pine plantations; however, it is most often combined with other methods and/or chemical release, and has been studied little on its own. Our study, conducted in the Virginia piedmont, compares the effects of various site preparation applications of imazapyr and their timings (July 23rd, September 3rd, and October 1st 2005) against a year-two chemical release (September 12th 2007), and an untreated check, all following a site preparation burn (June 15, 2005). Testing for additive effects, site preparation treatments were conducted with and without, sulfometuron methyl (SMAX) which targets herbaceous vegetation. Half of all treatments, including the check and release, received a year-one weed control treatment (H) of imazapyr and SMAX. Pines were measured every few years, including the latest measurement in year 14 (2019). Competing hardwood vegetation basal area was measured in year 14. All site preparation treatments reduced competition levels compared to the check, and an inverse relationship exists between competition level and pine volume. Adding SMAX resulted in less effective competition control, but had little effect on pine volumes. Adding H decreased average competition levels, and increased pine volumes. H treatments had the most effect at improving early season (July) applications. September and October treatments generally had more effect than July and the year-two release at controlling competing vegetation, and also showed higher individual pine tree volumes than all other treatments. Chemical site preparation treatments, even performed alone, appear to be valid means of improving pine stands.
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    A New Approach for Modeling Volume Response from Mid-Rotation Fertilization of Pinus taeda L. Plantations
    Scolforo, Henrique F.; Montes, Cristian R.; Cook, Rachel L.; Lee Allen, Howard; Albaugh, Timothy J.; Rubilar, Rafael A.; Campoe, Otavio C. (MDPI, 2020-06-06)
    Mid-rotation fertilization presents an opportunity to increase the economic return of plantation forests in the southeastern United States (SEUS). For this reason, the Forest Productivity Cooperative established a series of mid-rotation fertilization trials in Pinus taeda L. plantations across the SEUS between 1984 and 1987. These trials identified site-specific responses to nitrogen (N) and phosphorus (P) fertilizers, resulting in increased stand production for 6–10 years after fertilization. There are successful volume response models that allow users to quantify the gain in stand productivity resulting from fertilization. However, all the current models depend on empirical relationships that are not bounded by biological response, meaning that greater fertilizer additions continue to create more volume gains, regardless of physiological limits. To address this shortcoming, we developed a bounded response model that evaluates relative volume response gain to fertilizer addition. Site index and relative spacing are included as model parameters to help provide realistic estimates. The model is useful for evaluating productivity gain in Pinus taeda stands that are fertilized with N and P in mid-rotation.
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    Rethinking Productivity Evaluation in Precision Forestry through Dominant Height and Site Index Measurements Using Aerial Laser Scanning LiDAR Data
    Raigosa-García, Iván; Rathbun, Leah C.; Cook, Rachel L.; Baker, Justin S.; Corrao, Mark V.; Sumnall, Matthew J. (MDPI, 2024-06-07)
    Optimizing forest plantation management has become imperative due to increasing forest product demand, higher fertilization and management costs, declining land availability, increased competition for land use, and the growing demands for carbon sequestration. Precision forestry refers to the ability to use data acquired with technology to support the forest management decision-making process. LiDAR can be used to assess forest metrics such as tree height, topographical position, soil surface attributes, and their combined effects on individual tree growth. LiDAR opens the door to precision silviculture applied at the tree level and can inform precise treatments such as fertilization, thinning, and herbicide application for individual trees. This study uses ALS LiDAR and other ancillary data to assess the effect of scale (i.e., stand, soil type, and microtopography) on dominant height and site index measures within loblolly pine plantations across the southeastern United States. This study shows differences in dominant height and site index across soil types, with even greater differences observed when the interactions of microtopography were considered. These results highlight how precision forestry may provide a unique opportunity for assessing soil and microtopographic information to optimize resource allocation and forest management at an individual tree scale in a scarce higher-priced fertilizer scenario.
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    Sentinel-2 Leaf Area Index Estimation for Pine Plantations in the Southeastern United States
    Cohrs, Chris W.; Cook, Rachel L.; Gray, Josh M.; Albaugh, Timothy J. (MDPI, 2020-04-29)
    Leaf area index (LAI) is an important biophysical indicator of forest health that is linearly related to productivity, serving as a key criterion for potential nutrient management. A single equation was produced to model surface reflectance values captured from the Sentinel-2 Multispectral Instrument (MSI) with a robust dataset of field observations of loblolly pine (Pinus taeda L.) LAI collected with a LAI-2200C plant canopy analyzer. Support vector machine (SVM)-supervised classification was used to improve the model fit by removing plots saturated with aberrant radiometric signatures that would not be captured in the association between Sentinel-2 and LAI-2200C. The resulting equation, LAI = 0.310SR − 0.098 (where SR = the simple ratio between near-infrared (NIR) and red bands), displayed good performance ( R 2 = 0.81, RMSE = 0.36) at estimating the LAI for loblolly pine within the analyzed region at a 10 m spatial resolution. Our model incorporated a high number of validation plots (n = 292) spanning from southern Virginia to northern Florida across a range of soil textures (sandy to clayey), drainage classes (well drained to very poorly drained), and site characteristics common to pine forest plantations in the southeastern United States. The training dataset included plot-level treatment metrics—silviculture intensity, genetics, and density—on which sensitivity analysis was performed to inform model fit behavior. Plot density, particularly when there were ≤618 trees per hectare, was shown to impact model performance, causing LAI estimates to be overpredicted (to a maximum of X i + 0.16). Silviculture intensity (competition control and fertilization rates) and genetics did not markedly impact the relationship between SR and LAI. Results indicate that Sentinel-2’s improved spatial resolution and temporal revisit interval provide new opportunities for managers to detect within-stand variance and improve accuracy for LAI estimation over current industry standard models.