The Lower Coastal Plain of the southeastern United States is a major wood producing region. The region is characterized by a combination of nearly-level topography, poorly-drained soils, and high rainfall, which results in a perched water table in some soils that inundates the surface several times each year. Harvesting timber under wet site conditions often results in extensive soil compaction, rutting, soil displacement, and waterlogging. Forest managers are concerned that these visually-displeasing soil disturbances may cause site damage and reduced productivity. These concerns were addressed in an operational-scale field experiment conducted in South Carolina. The objectives of this experiment were to determine: (i) if soil disturbance changes key soil properties and processes; (ii) if soil disturbance reduces loblolly pine productivity; and, (iii) if disturbance can be mitigated with site preparation practices? Three 20-ha, 20-yr-old loblolly pine (Pinus taeda L.) plantations were harvested under wet and dry conditions to create a broad gradient in soil disturbance. Within each harvested plantation, a subset of 3-ha plots were site prepared by either bedding, or mole-plowing plus bedding, then all sites were established as 3rd -rotation pine plantations. Prior to site preparation, each plot was classified and mapped using a 5 by 5 soil disturbance (none to churned) by organic debris (none to slash piles) classification matrix. Within each plot, data were collected on several soil physical, chemical, and biological properties over a 2-yr period following site preparation. Key soil properties were integrated into a Soil Quality Index (SQI) and compared to aboveground productivity of 2-yr-old loblolly pine trees growing on closely-spaced (30 by 30 cm) bioassay plots planted across the gradient of soil disturbance. The soil physical properties were used to determine the least limiting water range (LLWR), the range in soil water content within which root growth is not limited. Soil compaction and deep rutting reduced the LLWR. Retention of logging slash improved the LLWR for compacted and rutted soils. Site preparation improved the quality of the soil physical environment across all levels of soil disturbance. Soil disturbance had no effect on soil chemical or biological properties as evidenced by no change in soil pH, ECEC, base saturation, available P, or net N mineralization with disturbance. The base saturation exceeded 80 % on all sites, with Ca saturation controlling soil pH. The high base saturation buffered any redox-induced changes in soil chemistry that would have resulted from disturbance. The results showed that high fertility is an important mechanism for buffering the potentially-negative effects of soil disturbance on the soil nutritional environment. Site preparation changed soil chemical properties, but the changes were probably associated with tillage effects on organic matter and clay content, not redox processes. The SQI showed that surface soil compaction and deep rutting reduced soil quality, mainly by decreasing the LLWR and aeration depth. Site preparation mitigated the effects of most disturbances on soil quality, evidenced by similar aboveground biomass production among soil disturbance classes after bedding. A regression model was developed for predicting aboveground biomass production as a function of SQI. SQI explained 73 % of the variation in aboveground biomass production. The regression model showed that compression tracks and rutting decreased aboveground biomass production compared to undisturbed soils. The long-term effect of these disturbances on productivity will depend on natural soil recovery processes. However, these early results suggest that compaction and rutting should be minimized on similar sites, especially if sites will not be bedded before reforestation. The mole-plow / bedding treatment increased aboveground biomass production, indicating that this experimental treatment may be a viable practice for enhancing productivity. / Ph. D.

A stochastic framework to simulate the process of initiation, diameter growth, death and self-pruning of branches in loblolly pine (Pinus taeda L.) trees was developed. A data set was obtained from a destructive sampling of whorl sections from 34 trees growing under different initial spacing. Data from dissected branches were used to develop a model for representing knot shape, which assumed that the live portion of a knot can be modeled by a one-parameter equation and the dead portion by assuming a cylindrical shape. For the developed knot model analytical expressions were derived for estimating the volume of knots (live/dead portions) for three types of branch conditions on simulated trees: (i) live branches, (ii) non-occluded dead branches, and (iii) occluded dead branches. This model was intended to recover information on knots shape and volume during the simulation process of branch dynamics. Three different components were modeled and hierarchically connected: whorl, branches and knots. For each new growing season, whorls and branches are assigned stochastically along and around the stem. Thereafter, branch diameter growth is predicted as function of relative location within the live crown and stem growth. Using a taper equation, the spatial location (X,Y,Z) of both live and dead portion of simulated knots is maintained in order to create a 3D representation of the internal stem structure. At the end of the projection period information on (i) vertical trend of branch diameter and location along and around the stem, (ii) volume of knots, and (iii) spatial location, size and type (live and dead) of knots can be obtained. The proposed branch model was linked to the individual-tree growth and yield model PTAEDA3.1 to evaluate the effect of initial spacing and thinning intensity on branch growth in sawtimber trees. The use of the dynamic branch model permitted generation of additional information on sawlog quality under different management regimes. The arithmetic mean diameter of the largest four branches, one from each radial quadrant of the log (i.e. Branch Index, BI) and the number of whorls per log were considered as indicators of sawlog quality. The developed framework makes it possible to include additional wood properties in the simulation system, allowing linkage with industrial conversion processes (e.g. sawing simulation). This integrated modeling system should promote further research to obtain necessary data on crown and branch dynamics to validate the overall performance of the proposed branch model and to improve its components. / Ph. D.

Informed forest management requires accurate, up-to-date information. Ground-based forest inventory is commonly conducted to generate estimates of forest characteristics with a predetermined level of statistical confidence. As the importance of monitoring forest resources has increased, budgetary and logistical constraints often limit the resources needed for precise estimates. In this research, the incorporation of ancillary information in planted loblolly pine (Pinus taeda L.) forest inventory was investigated. Additionally, a simulation study using synthetic populations provided the basis for investigating the effects of plot and stand-level inventory aggregations on predictions and projections of future forest conditions. Forest regeneration surveys are important for assessing conditions immediately after plantation establishment. An unmanned aircraft system was evaluated for its ability to capture imagery that could be used to automate seedling counting using two computer vision approaches. The imagery was found to be unreliable for consistent detection in the conditions evaluated. Following establishment, conditions are assessed throughout the lifespan of forest plantations. Using small area estimation (SAE) methods, the incorporation of light detection and ranging (lidar) and thinning status improved the precision of inventory estimates compared with ground data alone. Further investigation found that reduced density lidar point clouds and lower resolution elevation models could be used to generate estimates with similar increases in precision. Individual tree detection estimates of stand density were found to provide minimal improvements in estimation precision when incorporated into the SAE models. Plot and stand level inventory aggregations were found to provide similar estimates of future conditions in simulated stands without high levels of spatial heterogeneity. Significant differences were noted when spatial heterogeneity was high. Model form was found to have a more significant effect on the observed differences than plot size or thinning status. The results of this research are of interest to forest managers who regularly conduct forest inventories and generate estimates of future stand conditions. The incorporation of auxiliary data in mid-rotation stands using SAE techniques improved estimate precision in most cases. Further, guidance on strategies for using this information for predicting future conditions is provided. / Doctor of Philosophy / Informed forest management requires accurate, up-to-date information. Groundbased sampling (inventory) is commonly used to generate estimates of forest characteristics such as total wood volume, stem density per unit area, heights, and regeneration survival. As the importance of assessing forest resources has increased, resources are often not available to conduct proper assessments. In this research, the incorporation of ancillary information in planted loblolly pine (Pinus taeda L.) forest inventory was investigated. Additionally, a simulation study investigated the effects of two forest inventory data aggregation methods on predictions and projections of future forest conditions. Forest regeneration surveys are important for assessing conditions immediately after tree planting. An unmanned aircraft system was evaluated for its ability to capture imagery that could be used to automate seedling counting. The imagery was found to be unreliable for use in accurately detecting seedlings in the conditions evaluated. Following establishment, forest conditions are assessed at additional points in forest development. Using a class of statistical estimators known as small-area estimation, a combination of ground and light detection and ranging data generated more confident estimates of forest conditions. Further investigation found that more coarse ancillary information can be used with similar confidence in the conditions evaluated. Forest inventory data are used to generate estimates of future conditions needed for management decisions. The final component of this research found that there are significant differences between two inventory data aggregation strategies when forest conditions are highly spatially variable. The results of this research are of interest to forest managers who regularly assess forest resources with inventories and models. The incorporation of ancillary information has potential to enhance forest resource assessments. Further, managers have guidance on strategies for using this information for estimating future conditions.

The controversy regarding commercial thinning continues to intensify as pine plantation acreage in the south increases. This controversy has caused industrial and nonindustrial landowners to re-examine the economic returns from their plantation investments. This study was undertaken to develop investment guidelines for the management of loblolly pine plantations. Computer simulation was used to evaluate the effect on present value that four future price/market scenarios, three management regimes, and three mechanized thinning systems can have on current thinning investments. When the economic returns from thinning are compared with a no-thin management regime, simulation results indicate that long-term investment advantages favor thinning only slightly, regardless of the future price/market scenario assumed. This slight difference suggests that individual forest product companies may find other reasons such as wood flow, tax advantages, and future product requirements of their manufacturing facilities to be overriding factors for engaging in commercial thinning. Generally, short-run cost and production differences between thinning systems are more significant than the long-term investment effects. Consequently, the type of mechanized thinning system employed has a negligible impact on the total investment. / Ph. D.

Thirty-six eight-year-old white pine (Pinus strobus L.) trees were used to identify minesoil, plant moisture, and foliar nutrient properties influencing white pine growth on reclaimed mine sites in southwest Virginia. PRESSAll (SAS Views, 1984) was used to determine relationships between soil properties and growth, soil properties and functional environmental factors (plant moisture stress and foliar nutrients), and between functional environmental factors and growth. PRediction Error Sum of Squares (PRESS), Mean Square Error (MSE), and Multiple Correlation Coefficient (R²) were used as criteria for variable selection and model validation. Rooting-volume index, the reciprocal of the electrical conductivity (EC), and extractable P in the soil-sized fraction of the minesoils were the best validated variables, predicting tree heights with the smallest amount of unit error (APRESS of 0.86 m) and accounting for the highest R² ( R² = 53.06%). The depth of the rooting volume had the greatest effect on 2 early growth (R² = 7 .91%), but variation in the last four years of height growth appeared to be a function primarily of rooting volume (R² = 51.40, p < 0.0001). Relationships between soil properties and 2 functional environmental factors varied widely (R² = 0.00-27 .50%). Plant moisture stress was most highly associated with the volume of the soil-sized fraction (R² = 13.6%), foliar phosphorus with soil pH (R² = 22.5%), and foliar cations with anaerobic-mineralizable nitrogen (R² = 0.00-27 .5%). The relationship between functional environmental factors and growth was uniformly weak (R² = 0.00-14.97%). Plant moisture stress was consistently related to overall height and its increment over the last four years, but foliar nutrients were erratically related to growth. No significant relationships between other functional environmental factors and growth were detected. Minesoil indices for individual trees ranged from 47-147 (base age 50). The depth of minesoil for site index 80 (average for Southern Appalachia) was 40 cm. / M. For.

The pine engraver beetles (~ spp.:Coleoptera:Scolytidae) may be serious pests depending on certain prerequisite conditions. In their secondary or "normal" role they breed in slash and damaged, dying, and dead trees. The broods emerging from these sources normally attack similar material. When such material is scarce due to cessation of cutting operations in mid-season or when conditions are especially favorable for brood development, an excess of beetles is often produced which, due to the lack of more suitable material, attack healthy trees. Repeated attacks cause these trees to succumb and die. When normally healthy trees are weakened by fire, flood, defoliation, drought, stagnation, etc., then they become more acceptable host material for successful engraver attacks. When the production of a very large number of beetles in "normal" breeding material coincides with physiological stress in "healthy" trees, then population explosions can occur. When large numbers of beetles and low host vigor do not coincide, spot kills cornnon1y occur. According to Thatcher (32), spot kills, although not conspicuous, add up to large volumes of timber loss each year. / Ph. D.

To prevent the buildup of epidemic level mountain pine beetle populations, conditions of the stand environment they inhabit must be altered. Silvicultural treatment is the most effective means for doing this. Preventative treatments work best when applied while mountain pine beetle populations are still at the endemic population level. Therefore, information necessary for making decisions concerning mountain pine beetle populations in lodgepole pine stands needs to be included in the initial silvicultural prescription planning process, at a time before beetle populations reach outbreak numbers. In this dissertation, several quantitative descriptions of the mountain pine beetle/lodgepole pine relationship were investigated. Models were developed to 1) describe the temperature-dependent development of six mountain pine beetle life stages and 2) describe the amount of loss a stand could sustain if an epidemic level population were to occur in the stand. Concepts of mountain pine beetle risk rating were also discussed. These models and additional information pertaining to the mountain pine beetle/lodgepole pine relationship were incorporated into a knowledge-based system, the MPB Advisory System. This system was designed to help U.S. Forest Service silviculturists include decisions concerning mountain pine beetle populations in the stand management process. / Ph. D.

Studies were conducted to determine the incidence and severity of Heterobasidion annosum (Fr.) Bref. root rot in loblolly pine (Pinus taeda L.) unthinned plantations and subsoiled seed orchards and to demonstrate the potential for direct root colonization by percolated basidiospores. Twenty-two 0.02 ha circular plots were installed in nine unthinned loblolly pine plantations in Virginia. Five plantations were located on sites classified as high hazard for annosum root rot while four plantations were located on low hazard sites. Bulldozer excavation of the root systems permitted extensive analysis of annosum root rot incidence and severity which was substantiated by isolation of the asexual stage of the fungus from symptomatic resinous and stringy-decayed roots. On low hazard sites, 10 of 300 trees (3.3 percent) were colonized by H. annosum with 2 trees (0.7 percent) severely colonized ( > 1 percent of the total root system mass). On high hazard sites, 29 of 348 trees (8.3 percent) were colonized with 5 trees (1.4 percent) severely colonized. On low hazard sites, the predominant colonization symptom was stringy decay which indicated an older established disease situation as opposed to colonized trees on high hazard sites which exhibited resin-soaking characteristic of more recent infection and colonization. No basidiocarps were observed on any trees on low hazard plots while only 2 trees exhibited conks on high hazard sites. Mean radial increment growth differences between H. annosumcolonized and noncolonized trees were analyzed using the Duncan's Multiple Range test and for the 10-year period prior to excavation no significant growth reduction was observed. Due to low incidence and severity of annosum root rot in unthinned loblolly pine plantations and the absence of reduced radial increment growth, the disease is not a primary management consideration, especially on low hazard sites. However, the disease may be of secondary importance in managing first-generation unthinned loblolly pine plantations on high hazard sites due to inoculum production from residual stumps of H. annosum trees removed during thinning. The root systems of 2, 20 and 30 loblolly pines at the Chesapeake Corporation, Virginia Division of Forestry and Union Camp Corporation seed orchards, respectively, were excavated with a backhoe to permit intensive analysis of subsoiled roots for annosum root rot incidence and severity. The absence of wound callus, lack of adventitious root formation and the presence of a resin-soaked band greater than approximately 6 mm wide at the wound surface were three criteria for determining whether a lateral primary root had failed to heal following subsoiling. Soil texture was closely associated with the incidence and severity of general root disease as the wetter soil conditions at the Chesapeake Corporation seed orchard probably afforded a more amenable environment for the healing of subsoiled roots. Sandy, drought-susceptible soils at the Union Camp Corporation and Virginia Division of Forestry seed orchards were associated with the higher incidence and severity of root disease among subsoiled lateral primary roots. The asexual stage of H. annosum was not successfully isolated from resin soaked subsoiled root tissue at any of the three orchards. Duncan's Multiple Range analysis demonstrated that mean radial increment growth was significantly decreased among healthy and declining subsoiled trees at the three orchards. At the Union Camp Corporation orchard, when healthy and declining trees were subsoiled they exhibited significantly less radial increment growth than their respective control counterparts. Loblolly pine root segments were inoculated with a suspension of H. annosum basidiospores and observed using scanning electron microscopy. Appressorial-like structures occurred at distal ends of elongated germ tubes demonstrating probable direct infection of loblolly pine root segments. / Ph. D.

Understory forage production, species composition, and nutrient concentrations were studied in relation to overstory structure and site characteristics in thinned loblolly pine (Pinus taeda) plantations in the Virginia Piedmont. Stands exhibited a wide range in overstory basal areas (18.8 to 43.5 m²/ha) and site indices (14.2 to 23.8 m at base age 25 years). Understory forage production for the 0 to 2 m stratum averaged 610 kg/ha and ranged from 154 to 1690 kg/ha. Initially, differential models were used to develop prediction equations relating understory production to overstory characteristics, but an empirical prediction equation proved to be somewhat superior. Forage production was most predictable from total overstory basal area, canopy cover, and slope position. Understory species composition was analyzed with respect to overstory structural and site gradients, using vegetation ordination techniques. Species composition was less closely related to these gradients than was production; however, the greatest species diversity appeared to occur during the period following thinning but before crown closure, when successional and mid-tolerant species coexisted. Nutrient concentrations in forage material averaged 4643 cal/g for gross energy, 38.3 percent for invitro dry matter digestibility by white-tailed deer (Odoooiteus virginiana) and 8.4 percent for crude protein. There were no apparent trends of these nutrient concentrations with respect to overstory structural or site characteristics. Forage based carrying capacities for white-tailed deer were computed using values from this study for production and nutrient concentrations, and values from the literature for deer forage preferences and nutrient requirements. Results indicated that the pine habitat could support 0.03 to 0.19 lactating does per ha during the summer season, and that energy and not protein is likely the limiting nutritive parameter. Suggestions are made for future research in pine overstory-understory and wildlife habitat relationships. These include the use of experimental overstory manipulation followed by periodic remeasurements to directly observe changes in understory production and species composition, intensive sampling to determine specific local wildlife forage preferences, and the quantification of wildlife movements and population dynamics. / Ph. D.

Over the next few decades, timber harvest levels on the South's non-industrial private forestlands (NIPFs) are projected to increase by 40 percent. These ownerships include 75 percent of the commercial timberland in the South, and account for 64 percent of the timber volume harvested in the region annually. Long-term sustained yield of softwood timber volumes from NIPFs depends on successful reforestation of harvested pine stands and afforestation of marginal agricultural lands. Available technical assistance is regarded as a significant factor in NIPP tree planting accomplishment. This study compares technical assistance available to NIPFs from various sources and attempts to measure response to technical assistance in terms of acres planted. Four sources of technical assistance are considered: state forestry agencies, consulting foresters, industry landowner assistance departments, and industry procurement staffs. Extensive south-wide surveys of technical assistance available from these four sources were conducted to determine the types and degrees of assistance available. Cross-sectional comparisons were made between 29 sub-state zones in 12 southern states to explore variation in NIPF acres planted attributable to variation in technical assistance. The surveys located just under 2,000 foresters having some professional involvement with southern landowners in 1985. The number of consulting foresters operating in the South seems to be growing, while the number of landowners enrolled in industry landowner assistance programs (LAPs) is also increasing. Assistance available to NIPF owners from all sources ranges from advice and recommendations to actual performance of site preparation and tree planting. The types and intensities of technical assistance are variable both within and across forester types. A cross-sectional statistical analysis using multiple linear regression was unable to demonstrate a significant south-wide effect of technical assistance on NIPF tree planting. Within the range of technical assistance presently available, variation in technical assistance did not prove to be a significant predictor of tree planting accomplishment. The results of this study indicate that diversity in the NIPF population, combined with diversity in silvicultural and market potential pine production, prevents quantification of a regional effect of technical assistance. A positive correlation between forester numbers and NIPF tree planting accomplishments was found. But only timber harvest levels and cost share expenditures were significant predictors of acres planted in multiple variable models. / Master of Science