One hundred and twenty-six stands were sampled using a stratified random design in a 6880 hectare Appalachian Oak Forest in southwest Virginia. The objective was to determine the present distribution patterns of tree species and community types and to relate their occurrence to site factors. Of the 52 tree species recorded, the dominants in order of decreasing importance were Acer rubrum, Quercus rubra, Liriodendron tulipifera, Quercus prinus, Acer saccharum and Quercus coccinea. Most site factors of importance, including elevation, lithology, landform, slope position, steepness, exposure, and soil depth appeared to influence the distribution of individual species and community types through their effect on local moisture and temperature conditions. Different site factors best explained the distribution of various species in a multiple regression analysis, thus suggesting that these species are distributed independently of each other. Stand history and interaction between site factors appeared to confound the species-site relationships examined and may explain the large portion of variation unaccounted for by the regressions. Stands were placed in one of six community types with the aid of polar ordination. Three community types were dominated by oak and showed considerable intergradation of species and site preferences. The dominant oaks shifted from Quercus rubra to Quercus prinus to Quercus coccinea on progressively drier sites. Sugar maple-mixed hardwoods, Yellow-poplar, and Hemlock community types were more discrete when compared to the oak community types. Stands dominated by Acer saccharum or Tsuga canadensis occurred mostly in relatively cool, moist conditions at mid to upper elevations, while most stands dominated by Liriodendron tulipifera were in moist locations at lower elevations. Results indicate that shifts in the composition of forest stands when compared to presettlement forests may be attributed to selective logging practices and to the demise of American chestnut. / Master of Science

The development of oak stems of advance regeneration and stump sprout origin was studied during a two-year period following clearcutting and whole-tree removal in eight midslope stands in the Ridge and Valley Province of southwestern Virginia. Oak regeneration was also characterized in several older clearcuts. Height and diameter of oaks of stump sprout origin in the two-year-old stands was significantly greater than that of advance regeneration stems, and the difference in size among regeneration types appeared to persist into the oldest (17- and 28-year-old) stands sampled. Chestnut oak, which had been the dominant oak species in most pre-harvest stands, had higher density of advance regeneration stems, higher frequency of stump sprouting, and greater sprout production per stump than scarlet or black oak two years after harvesting. However, shoot growth of advance regeneration during the two-year period did not differ among oak species when initial stem site and vigor were accounted for taller stump sprouts in the two-year-old stands were associated with more productive sites (as indicated by site index, topographic variables, and vegetation composition), whereas biomass production per stump was less closely related to site quality. Height and diameter growth of oak advance regeneration during the two-year post-harvest period were significantly greater on sites of medium quality than OD sites of low quality. Density of well-established oak stems of advance regeneration origin two years after harvest was greatest in stands of site index 55-65 (base age 50), and fell off on sites of higher and lower quality. Models developed to predict two-year stump sprout production from characteristics of the parent tree generally explained less than 40 percent of the variation among stumps, while models describing growth of advance regeneration individuals from pre-harvest measurements accounted for as much as 82 percent of the variation. Regeneration in most of the two-year-old stands appeared adequate for restocking of oaks to at least their pre-harvest level, although stems will probably be widely spaced and mostly of stump sprout origin on both the poorest and the most productive sites. / Ph. D.

Many existing Piedmont hardwood stands are composed of trees that are largely under 45 cm in diameter and contain a desirable oak component, as well as large amounts of undesirable red maple and sourwood. In stands under even-aged silviculture, season of harvest can be used as an effective management tool to favor different species compositions. If oak or other hardwood production is the management objective a dormant season harvest will result in increased sprout vigor of all oak as well as non-oak species. If pine conversion is the objective then a growing season harvest will reduce the vigor of all hardwood species and allow for easier competition control. The higher densities of all classes of regenerants on better sites indicates control will be more difficult. / Master of Science

Canopy mortality. species abundance. and the species composition and origin of regeneration in mixed oak forests were studied following a 1900 ha man-caused early growing season wildfire in Shenandoah National Park. in the Blue Ridge Physiographic Province. Virginia. Pre-fire stands were dominated by chestnut. scarlet, and northern red oaks growing on medium quality sites (50 year upland oak site index 16-20 m). Permanent vegetation plots were established in four stands for each of high and low levels of fire intensity. and unburned stands. High-intensity fire killed 67% of the basal area and 81% of the trees, whereas low-intensity fire resulted in mortality of 8% of the basal area and 15% of the trees. The mean height of stem-bark char accounted for 91% and 95% of the variation in percent of the basal area and number of trees killed by fire, respectively. Logistic regression models were developed to predict the probability of fire-induced individual tree mortality (top-kill) as a function of DBH and height of stem-bark char for chestnut oak, scarlet and northern red oaks, pignut hickory, blackgum. and red maple. Blackgum and chestnut oak were the most fire resistant species studied. High-intensity fire resulted in the development of a new stand, whereas low-intensity fire resulted in thinning of the overstory and understory. Most species present in pre-fire stand reproduced via basal sprouts, chestnut oak sprouts were the most abundant stems taller than 1 m two growing seasons after high-intensity fire. Tree-of-heaven was the only species to regenerate by seed and able to match the height growth of oak basal sprouts. This research suggests that oaks are capable of replacing themselves on medium quality sites following wildfire-induced canopy removal in 55 to 60 year old stands. / Master of Science

I studied aspects of the population ecology of table mountain pine, <i>Pinus pungens</i>, in pine-oak forests on Brush Mountain, Montgomery County, Virginia. The objective of this study was to examine the age structure and recruitment dynamics of <i>P. pungens</i>, a fire-adapted conifer, and to determine whether <i>P. pungens</i> populations would persist in the absence of fire. The age distributions of <i>P. pungens</i> on the Brush Mountain study sites were bimodal, with peaks in seedling and canopy age classes and a major trough in the sapling and understory age classes. Age and diameter of <i>P. pungens</i> understory and canopy trees were positively related, but diameter was a poor predictor of age. The sparse representation of <i>P. pungens</i> in the seedling, sapling, and understory strata of the Brush Mountain sites strongly indicates that under current disturbance regimes, maintenance of <i>P. pungens</i> populations is unlikely. The prevalence of oak advance regeneration ard other gap-exploiting woody species such as ard <i>Sassafras albidum</i> and <i>Nyssa sylvatica</i> suggests that gap replacement processes would favor these species and not <i>P. pungens</i> Recruitment of <i>P. pungens</i> was not limited by seedfall from serotinous cones or from seed predation by animals. Seedfall occurred throughout the year at low levels and was concentrated in the spring and summer months. The unavailability of seedling habitat strongly limited recruitment of <i>P. pungens</i> seedlings. Litter depth and type were important determinants of <i>P. pungens</i> seedling habitat; seedlings occurred almost exclusively in shallow pine litter. There was little overlap between the distributions of habitat variables for seedlings and random points in the forest, indicating that suitable seedling habitat was rare. Summer drought and substrate were important factors influencing the establishment and survivorship of seedlings. Greenhouse studies were conducted to determine the influence of leaf litter and water regime on early establishment of <i>P. Pungens</i>. Emergence of seedlings was consistently highest in pine litter and lowest in hardwood litter at all water regimes and in litter-free treatments at low watering intervals. Survival of seedlings was enhanced by litter at low water regimes. Significant litter/water interactions indicated that the effects of litter and water regime were not independent; litter significantly decreased the loss of soil moisture from experimental treatments. Evidence suggests that depression of <i>P. pungens</i> seedling emergence in hardwood litter was due to physical-mechanical effects. / Ph. D.

During June 1990 - November 1993 I measured the responses of black bears (Ursus americanus) in Shenandoah National Park (SNP), Virginia to gypsy moth (Lymantria dispar) induced oak (Quercus spp.) mortality. Oak species composed >50% of the forest canopy of SNP, and oak mortality rates ranged from 1- ≥48%. I compared black bear population dynamics, food habits, movements and habitat use to preinfestation data collected in SNP from 1982 - 1985. Scat analysis indicated that the current diet of SNP’s black bear population includes proportionally more soft mast in the fall and more soft mast and ants (Formicidae spp., P<0.0001) in the summer than did the preinfestation diet. Fewer acorns (Quercus spp. mast, P=0.03) and squawroot (Conopholis americana, P=0.01) were consumed in the fall and summer respectively. No decline in the physical condition of adult females (P=0.91), subadult males (P=0.34) or subadult females (P=0.94) was evident. Adult male physical condition declined (P=0.03) for unknown reasons. The mean age of neither female (P=0.99) nor male bears (P=0.54) was different from preinfestation data. Mean litter size - 2.25 cubs - did not differ (P=0.49) froma preinfestation mean of 2.0 cubs. Survival of radio-collared female bears was 100%, indicating that the female survival rate has not declined from a high preinfestation survival rate. Minimum cub survival rate to 1 year was 64.7%. Fall and annual home ranges of female bears were smaller (P=0.001 and P=0.002, respectively) than during preinfestation years. Use of forest cover types differed from availability during the summer (P<0.01), early fall (P<0.0001) and late fall (P<0.001) and when compared to preinfestation data. Use of stands with different levels of oak mortality was not different from availability during the summer (P=0.1) but was different during the early fall (P<0.005) and late fall (P<0.001). / Master of Science

Master of Science