This study compares financially optimal uneven-aged and even-aged silvicultural regimes of loblolly pine (Pinus Taeda). Uneven-aged regimes which maximize net present value (NPV) are found by quantifying the effects of diameter distribution (Q factor), maximum diameter, cutting cycle, and residual basal area on NPV. For the benchmark inputs, the regime yielding the highest NPV had a maximum diameter of 12 inches, residual basal area of 45 ft²/acre, and a cutting cycle of 11 years. Financially optimal even-aged regimes are taken from published literature of even-aged silviculture. Even-aged and uneven-aged silvicultural regimes are simulated starting from, 1) bare land, 2) a balanced uneven-aged loblolly pine stand, and 3) a mature even-aged loblolly pine stand. For the three starting conditions and selected benchmark variable values, simulation of even-aged silviculture yields NPVs of $877, $2,152 and $3,400 per acre and simulation of uneven-aged silviculture yields NPVs of $644, $2,084, and $2,569 per acre. Sensitivity analysis shows, for the levels of the variables tested, that even-aged silviculture yields higher NPVs than uneven-aged silviculture when starting from bare land or from a mature even-aged stand. When starting from an uneven-aged stand, for the variable values tested, uneven and even-aged silviculture are financially very competitive. Aside from the aesthetic benefits of avoiding clearcutting under uneven-aged silviculture, non-timber considerations between loblolly pine silvicultural systems are not well documented. Resource professionals hold opinions often in direct conflict with each other regarding the non-timber costs and benefits of even-aged and uneven-aged silviculture when considering wildlife, soil and water, and catastrophic damage events. / Master of Science

Mathematical methods of assessing the spatial autocorrelation associated with individual tree characteristics in forest stands were identified. These measures were used to investigate the spatial autocorrelation of discrete tree characteristics including the species, product, and defect classifications. With the exception of the species classification, none of the discrete tree characteristics examined showed any evidence of significant (α = 0.05) levels of spatial autocorrelation in loblolly pine stands. The significant autocorrelation of the species classification was probably due to past stand history or microsite variability rather than overall stand conditions such as age, density, or percent pine. The relationship between the level of spatial autocorrelation associated with basal area and several descriptive stand characteristics was also examined. No strong relationships were identified but trends were noticed between the autocorrelation measures and measures of stand competition such as basal area and crown competition factor. The measures of spatial association indicate positive autocorrelation between the characteristics of neighboring trees at very low levels of competition with the autocorrelation becoming increasingly negative as competition increases. At extremely high levels of competition, the spatial autocorrelation measures become positive again, reflecting the stagnated condition of the stand. Methods were developed, using the measures of spatial autocorrelation, to assign characteristics to individual trees in computer generated stands. These methods, applicable for discrete or continuous characteristics; assign the characteristics to individual trees depending on the spatial location of the individual tree and the locations and characteristics of its neighbors. / Ph. D.

Yellow poplar (Liriodendron tulipifera L.) and loblolly pine (Pinus taeda L.), families 2-8 and 540, seedlings were fumigated with 0.07 ppm ozone, 0.06 ppm sulfur dioxide 0.07 ppm ozone + 0.06 ppm sulfur dioxide, 0.06 ppm sulfur dioxide + 0.10 ppm nitrogen dioxide and 0.07 ppm ozone + 0.06 ppm sulfur dioxide + 0.10 ppm nitrogen dioxide for 35 consecutive days, 6 hr/day. Control seedlings received charcoal-filtered air. Ozone or sulfur dioxide did not significantly affect height growth or dry weight of yellow poplar seedlings. All other treatments significantly reduced height growth and dry weight after 2 weeks of fumigation. Height growth effects of loblolly pine families were not repeatable from one year to the next in replicate experiments and weekly growth trends in the two experiments were reversed. Environmental factors related to time of year were thought to be involved with this growth trend reversal. Root dry weight was found to be a more sensitive indicator of air pollution stress than either shoot dry weight, height growth or visible symptoms. Loblolly families 2-8 and 540 were not found to be differentially sensitive to pollutant treatments. Loblolly pine seedlings, nonmycorrhizal and mycorrhizal with Pisolithus tinctorius, were fumigated with 0.07 ppm ozone and 0.06 ppm sulfur dioxide singly and in combination, 6 hr/day, for 35 consecutive days. Height growth of mycorrhizal and nonmycorrhizal seedlings was not affected by fumigation. Root dry weight of nonmycorrhizal seedlings was significantly reduced by all pollutant treatments in two replicate experiments. A similar reduction in root dry weight of mycorrhizal seedlings did not occur. Shoot dry weight of nonmycorrhizal seedlings was reduced in four of six pollutant treatments, and in one of six treatments of mycorrhizal seedlings. Mycorrhizal formation was extensive regardless of treatment. Apparent photosynthesis, measured every 4 days, was variable and significant differences among treatments did not occur. Total reducing sugar concentrations of roots were an inconclusive indicator of air pollutant stress. / Ph. D.

Short term studies have suggested that ground based timber harvesting on wet sites can alter soil properties and inhibit early survival and growth of seedlings. Persistence of such negative effects may translate to losses in forest productivity over a rotation. During the fall and winter of 1989, numerous salvage logging operations were conducted during high soil moisture conditions on wet pine flats in the lower coastal plain of South Carolina following Hurricane Hugo. A long-term experiment (split-plot within an unbalanced randomized complete block design) allowed assessment of long term effects of rutted and compacted primary skid trails and subsequent site preparation on soil properties and loblolly pine (Pinus taeda L.) productivity. The experiment had 12 blocks, four levels of site preparation as the whole plot factor (bedding, disking with bedding, disking, and no site preparation), and two levels of traffic as the subplot factor (primary skid trail, no obvious traffic). After 23 years, bedding and disking with bedding treatments effectively enhanced soil physical properties and stand productivity via promoting greater survival and stocking, but had little effect on the size of individual trees relative to disking and no site preparation treatments. Primary skid trails significantly reduced the size of individual trees, but had no appreciable long term effects on soil properties or stand productivity after 23 years. The study suggests that bedding is the most efficient practice to enhance soil properties, seedling survival, and stand productivity on wet sites. However, site preparation is not necessary for these soils and sites, if strictly intended to restore soil properties and stand productivity in primary skid trails. Reduction in individual tree sizes on primary skid trails emphasizes benefits in minimizing the spatial extent of disturbance. / Master of Science / Heavy equipment traffic associated with ground-based timber harvesting has potential to alter soil properties resulting in lower productivity of the subsequent forest. Various soil tillage techniques have been suggested to offset changes in soil properties and forest productivity on disturbed soils, and to enhance soil properties and forest productivity on undisturbed soils. An experiment was conducted on low-lying Atlantic Coastal Plain sites to compare the effects of four soil tillage treatments (bedding, disking, disking with bedding, no tillage) on soil properties and forest productivity 23 years after treatments were installed. Bedding displaces soil from furrows into continuous, linear mounds called beds, such that bed surfaces are above the original soil surface. Disking is a tillage practice commonly implemented in agriculture. For the disking with bedding treatment, plots were disked followed by bedding. The no tillage treatment served as a control. Additionally, the experiment provided comparison of soil properties and forest productivity between soils heavily disturbed by logging activities and relatively undisturbed soils. Bedding and disking with bedding created favorable, localized soil conditions that promoted greater loblolly pine survival which translated to approximately double the total stand volume per unit area relative to disking and no tillage treatments. Differences in the sizes of individual trees among tillage treatments were minimal. Heavily disturbed soils and soils undisturbed by logging activity were similar in terms of soil properties and loblolly pine volume per unit area; however, individual trees were smaller on heavily disturbed soils. The implications of this study provide practical guidance for forest management decisions. Of treatments compared, bedding is the most efficient to increase total stand productivity on poorly drained sites. Disking with bedding offers no additional benefits, but is more expensive to implement. Results also imply that soils disturbed by logging have potential to recover over time such that long term forest productivity is sustained. However, the reduction in individual tree sizes emphasizes benefits of minimizing soil disturbance during timber harvests.

Mid-rotation fertilization and vegetation control are some of the most common silvicultural treatments in loblolly pine (Pinus taeda L.) plantations in the southeastern United States. Competing vegetation is commonly thought to sequester fertilizer nitrogen (N) and reduce the potential growth response to a mid-rotation fertilization treatment. This experiment aims to identify what proportion of applied N fertilizer is retained in the crop tree pine foliage, and the degree to which understory vegetation is competing for this resource. Our mid-rotation loblolly pine plantation received an application of 15N fertilization (urea 365 kg/ha, at 46% N by weight, i.e. 168 kg/ha of N) and a portion of plots received an understory vegetation control (basal spray application of triclopyr; 13.6% active ingredient) treatment either before fertilization or not at all. One-year post-fertilization, 15N contents within pine foliage, leaf fall/leaf litter, forest floor, and soil were measured, as was competing vegetation presence. There was significant variation in applied nitrogen acquisition among the different ecosystem components measured, with 0-15 cm soils retaining a majority at 32-37% added 15N. Differences in fertilizer N acquisition in pine foliage between plots with and without understory vegetation control was marginally significant (p = 0.06) with pine foliage in plots without understory vegetation capturing greater 15N (4.3% greater). Red maple (Acer rubrum) and oak species (Quercus spp.) were the most common competitors but neither had a uniquely pronounced effect on pine nitrogen sequestration. My data indicate that increasing competition reduces fertilizer N foliar concentrations in crop pine trees but at a modest rate and equally across species groups. An unrefined threshold determining when fertilizer N capture in crop pine trees was affected was found at 3.1 m2/ha of competing vegetation basal area. This site will continue to be monitored over time to assess fertilizer N retention in loblolly pine each year after fertilization and evaluate the fertilizer N capture within competing vegetation. / Master of Science / Some of the most prevalent management practices for mid-rotation (age 15, i.e., roughly halfway through a crop cycle) loblolly pine (Pinus taeda L.) plantations in the southeastern United States are fertilization and vegetation control. Nitrogen (N) is consistently one of the most limiting factors to productivity. The addition of N via fertilization is therefore a common forestry practice. However, when a stand is fertilized, the added resource is partitioned and cycled throughout the ecosystem. It is presumed that the amount of fertilizer N obtained by crop trees in a plantation is dependent on the level of competing vegetation (i.e., weed-trees and shrubs) present on site. Controlling competing vegetation prior to fertilization may therefore be warranted under certain conditions. To date, the amount of competing vegetation where it begins to impact fertilizer uptake by the crop tree is unknown. This study aims to elucidate this competing vegetation threshold to better inform mid-rotation management of loblolly pine plantations. This study examined applied fertilizer N capture in ecosystem components with varying levels of understory vegetation, and found more fertilizer N in pine foliage when understory vegetation was completely removed prior to fertilization. No single understory hardwood weed species had a uniquely strong influence on crop tree productivity uptake. Plots that ranked in the upper third in competing vegetation presence did have significantly less foliar fertilizer N in the pine crop trees. Additional replication of this study would be necessary to determine a universal threshold of competing vegetation which would trigger the removal of competing vegetation prior to fertilization.

No description available.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1984. / Includes bibliographical references (p. 54-56).

To improve habitat quality for wildlife, habitat managers prescribe various disturbances. Habitat management techniques alter the vegetation structure, composition, and quality, changing food and cover resources and availability. To investigate how habitat management and vegetation heterogeneity affect space use by wildlife species, I deployed 81 camera-traps and collected fine scale vegetation data across a variety of treatments (i.e., canopy reduction, prescribed fire, and herbicide application) in a managed loblolly pine forest. I created a new method for accounting for imperfect detection and error in camera count data. My method provided better inference about the effects of variables on animal use. Species responded differently to different functional groups of plants, but predicted use from generalized additive models showed higher use in the most intensively managed pine stands, indicating that management promotes animal use by improving habitat quality. Animals used every treatment, indicating the need for heterogeneity in resources when managing wildlife.

Anticipated climate change and increasing wood demand require dependable diameter growth models for adaptive forest management. We used a mixed-effects modeling approach with Forest Inventory and Analysis (FIA) data to fit diameter growth models for loblolly pine, other softwood species (slash pine, shortleaf pine, and longleaf pine), sweetgum, and other hardwood (southern red oak, red maple, and water oak) species. Climatic variables coupled with individual tree attributes and competition factors improved climate insensitive models. Growth of loblolly pine and sweetgum was positively correlated with mean temperature of the coldest month. Mean temperature of the warmest month negatively influenced diameter growth of loblolly pine and other hardwood species. Growing season precipitation and summer precipitation balance had negative effects on the growth of softwood and hardwood species, respectively. Inclusion of FIA plot as random effect improved model fit statistics and residual distribution of climate sensitive models. These findings will be useful to managers for recalibrating diameter growth models resulting in improved biomass yield and volume estimates that will better inform decisions.