Browsing by Author "Amateis, Ralph L."

Now showing 1 - 7 of 7
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    Dimensionally Compatible System of Equations for Tree and Stand Volume, Basal Area, and Growth
    Sharma, Mahadev (Virginia Tech, 1999-10-28)
    A dimensionally compatible system of equations for stand basal area, volume, and basal area and volume growth was derived using dimensional analysis. These equations are analytically and numerically consistent with dimensionally compatible individual tree volume and taper equations and share parameters with them. Parameters for the system can be estimated by fitting individual tree taper and volume equations or by fitting stand level basal area and volume equations. In either case the parameters are nearly identical. Therefore, parameters for the system can be estimated at the tree or stand level without changing the results. Data from a thinning study in loblolly pine (Pinus taeda L.) plantations established on cutover site-prepared lands were used to estimate the parameters. However, the developed system of equations is general and can be applied to other tree species in other locales.
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    The Effects of Ice Damage on Management Decisions for Loblolly Pine Plantations located in the Piedmont Region of Virginia
    Goodnow, Robert W. Jr. (Virginia Tech, 2002-02-15)
    The effect of ice damage on loblolly pine (Pinus taeda) plantations in the Piedmont region of Virginia was examined to discover if management decisions can minimize net present value losses. A simulation approach was used for the analysis. Loblolly pine plantations were simulated using the growth and yield model, Trulob. Ice damage was factored into the model using prediction equations from a previous study. A decision tree framework was used to determine which management plans resulted in the highest net present value. The results show that ice storms can cause significant losses to the net present value of loblolly plantations. In most instances changing management plans could not minimize losses. In situations where altering management plans can result in higher net present values if ice occurs, landowners should also be aware of the suboptimal net present value they will be returned if these plans are followed and no ice storms occur.
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    Effects of Mid-Rotation Release on Forest Structure, Wildlife Habitat, and Pine Yield
    Cheynet, Kyla Ingeborg (Virginia Tech, 1999-11-30)
    The effects of two forms of mid-rotation release on thinned, fertilized loblolly pine (Pinus taeda L.) plantations in Virginia were examined: aerial imazapyr and basal triclopyr application. Imazapyr measurement plots were installed in nine Piedmont and twelve Coastal Plain plantations operationally released with imazapyr, and triclopyr measurement plots were installed within a controlled fertilization/release study spanning both regions. No differences in volume were detected following triclopyr release. All release dates combined, Piedmont released areas averaged 0.06 m3/tree (18%) greater than the control and Coastal Plain released areas averaged 0.05 m3/tree (14%) greater than the control. Reductions in hardwood basal area, stem density, and shrub stratum cover were observed for both forms of release. Reductions in shrub stratum richness and diversity were also documented for imazapyr release; however, trends indicate that richness and diversity, as well as stem density and shrub stratum cover, may recover to pre-treatment levels. Herbaceous vegetation was increased on triclopyr sites, which was reflected in an elevated turkey (Meleagris gallopavo sylvestris L.) food/brood index. Following imazapyr release, habitat suitability index (HSI) values for pine warblers (Dendroica pinus L.) and black-capped chickadees (Parus atricapillus L.) increased due to reductions in canopy hardwoods and increases in snags. Reduced shrub stratum density resulted in a lower bobwhite quail (Colinus virginianus L.) cover index on imazapyr-released areas.
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    Modeling the biomass partitioning of loblolly pine grown in a miniature-scale plantation
    Russell, Matthew B. (Virginia Tech, 2008-01-28)
    Stand conditions influence the partitioning of biomass to stem, foliage, branch, and root components. Using data from 4 to 6-year old loblolly pine (Pinus taeda L.) trees grown in a miniature-scale spacing trial, this study determined the effect of initial planting density on the biomass partitioning of loblolly pine. An analysis of covariance concluded that density did not have a significant effect on the relative amount of biomass in aboveground components.Some measures of partitioning tradeoffs (such as root: shoot ratio) showed a significant positive slope when regressed against trees per hectare. Systems of linear equations were developed based on tree measurements and age, and additivity was specified. By taking into account contemporaneous correlations among tree components, seemingly unrelated regression (SUR) methodologies led to efficient parameter estimates. When compared to studies with mature trees at operational scales, results from the miniature-scale trees showed similar trends. Stem and woody roots were 70 and 14% of total mass, respectively. Since these miniature-scale trees were physiologically young at time of harvest, allocation of mass to foliage continued to be a priority, occupying 10% of total mass.
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    Regional Assessment of Carbon Pool Response to Intensive Silvicultural Practices in Loblolly Pine Plantations
    Vogel, Jason G.; Bracho, Rosvel; Akers, Madison; Amateis, Ralph L.; Bacon, Allan R.; Burkhart, Harold E.; González-Benecke, Carlos; Grunwald, Sabine; Jokela, Eric J.; Kane, Michael B.; Laviner, Marshall A.; Markewitz, Daniel; Martin, Timothy A.; Meek, Cassandra; Ross, Christopher Wade; Will, Rodney E.; Fox, Thomas R. (MDPI, 2021-12-30)
    Tree plantations represent an important component of the global carbon (C) cycle and are expected to increase in prevalence during the 21st century. We examined how silvicultural approaches that optimize economic returns in loblolly pine (Pinus taeda L.) plantations affected the accumulation of C in pools of vegetation, detritus, and mineral soil up to 100 cm across the loblolly pine’s natural range in the southeastern United States. Comparisons of silvicultural treatments included competing vegetation or ‘weed’ control, fertilization, thinning, and varying intensities of silvicultural treatment for 106 experimental plantations and 322 plots. The average age of the sampled plantations was 17 years, and the C stored in vegetation (pine and understory) averaged 82.1 ± 3.0 (±std. error) Mg C ha−1, and 14.3 ± 0.6 Mg C ha−1 in detrital pools (soil organic layers, coarse-woody debris, and soil detritus). Mineral soil C (0–100 cm) averaged 79.8 ± 4.6 Mg C ha−1 across sites. For management effects, thinning reduced vegetation by 35.5 ± 1.2 Mg C ha−1 for all treatment combinations. Weed control and fertilization increased vegetation between 2.3 and 5.7 Mg C ha−1 across treatment combinations, with high intensity silvicultural applications producing greater vegetation C than low intensity (increase of 21.4 ± 1.7 Mg C ha−1). Detrital C pools were negatively affected by thinning where either fertilization or weed control were also applied, and were increased with management intensity. Mineral soil C did not respond to any silvicultural treatments. From these data, we constructed regression models that summarized the C accumulation in detritus and detritus + vegetation in response to independent variables commonly monitored by plantation managers (site index (SI), trees per hectare (TPH) and plantation age (AGE)). The C stored in detritus and vegetation increased on average with AGE and both models included SI and TPH. The detritus model explained less variance (adj. R2 = 0.29) than the detritus + vegetation model (adj. R2 = 0.87). A general recommendation for managers looking to maximize C storage would be to maintain a high TPH and increase SI, with SI manipulation having a greater relative effect. From the model, we predict that a plantation managed to achieve the average upper third SI (26.8) within our observations, and planted at 1500 TPH, could accumulate ~85 Mg C ha−1 by 12 years of age in detritus and vegetation, an amount greater than the region’s average mineral soil C pool. Notably, SI can be increased using both genetic and silviculture technologies.
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    Simulation of Individual Tree Growth and Stand Development in Loblolly Pine Plantations on Cutover, Site-Prepared Areas
    Burkhart, Harold E.; Farrar, Kenneth D.; Amateis, Ralph L.; Daniels, Richard F. (Virginia Tech. Division of Forestry and Wildlife Resources, 1987)
    A forest stand simulator, PTAEDA2, was developed to model growth in loblolly pine (Pinus taeda L.) plantations on cutover, site-prepared areas. Individual trees were used as the basic growth units. In PTAEDA2, trees are assigned coordinate locations in a stand and 'grown' annually as a function of their size, the site quality, and the competition from neighbors. Growth increments are adjusted by stochastic elements representing genetic and microsite variability. Mortality is generated stochastically through Bernouli trials, Subroutines were developed to simulate the effects of hardwood competition, thinning, and fertilization on tree and stand development. Options for varying the spatial location of trees to mimic randomness in machine and hand planting operations are also included.
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    Yields and Size Class Distributions for Unthinned Loblolly Pine Plantations on Cutover Site-Prepared Lands
    Amateis, Ralph L.; Burkhart, Harold E.; Knoebel, Bruce R.; Sprinz, Peter T. (Virginia Tech. Division of Forestry and Wildlife Resources, 1984)
    Data from plots established in unthinned loblolly pine plantations on cutover site-prepared lands were used to develop size class distribution and yield predictions. The data come from plantations of loblolly pine established over much of its natural range and represent a wide variety of stand conditions and site-preparation treatments. A three parameter Weibull density function was used to model diameter distributions, and a computer program, COYIELD, was developed to predict yields from stand attributes. The predicted yields should satisfactorily represent many sites in the Piedmont and Coastal Plain regions of the Southern United States.