Thinning from above and below were compared using an economic optimizing dynamic program, FORTE (Arthaud 1986). Economically optimal (net present value maximizing) thinning regime and rotation age were determined for benchmark economic and model inputs. Sensitivity of net present value and optimal management regime were tested for varying interest rates (6 or 8%), site indexes (50, 60 and 70, base 25 years), fixed and variable thinning costs, planting density (440, 680 and 910 trees per acre), stumpage prices and thinning type. Given the same assumptions, thinning from below consistently provided the higher net present value for the optimal regime than thinning from above. For the benchmark assumptions, both thinning types had two thinnings in their optimal regimes. Optimal rotation age and thinning timings occur later when thinning from above. Both thinning types provided higher net present values than not thinning under all conditions except pulpwood management. / Master of Science

Loblolly pine that is winter-sown in the greenhouse and spring-outplanted has been observed to exhibit growth abnormalities in the form of multiple apical and needleless shoots. Seedlings that exhibit growth abnormalities are of questionable value in the evaluation of progeny tests. The use growth data from this seedling material could result in biased and erroneous or invalid conclusions about individual tree or family performance. To determine the causes of growth abnormality development, and to suggest possible remedies, two experiments were initiated. The first experiment examined the effects of raising five Virginia controlled-cross families in two different greenhouses and subsequently outplanting the seedlings on two contrasting sites. The second examined the effects of pre-planting exposure to 0, 4, or 6 weeks of shortened days followed by 0, 400 or 600 hours of chilling and post-planting supplemental water. Experiment one results indicated that abnormalities were more apparent at the better growing site. Further, pre-planting hardening-off likely increased the dormancy status of the seedlings and somewhat alleviated growth abnormalities. It was determined that families varied in the expression of abnormalities. Abnormalities were only observed during the first summer after outplanting; symptoms were alleviated after overwintering. Experiment two results indicated that treatments that influenced the dormancy status of the seedlings influenced the development of growth abnormalities. Pre-planting shortened days resulted in increased needles per total stem units for the second flush. Pre-planting chilling and post-planting supplemental water increased apical dominance. / Master of Science

During the last three years, 80% of mining permits in Virginia listed forestland as the post-mining land use. Adequate stocking and growth of tree stands at time of bond-release eligibility and beyond is an important beginning for returning mined lands to a productive state. In order to ensure reforestation success, biological constraints, including low mine soil fertility and competition from herbaceous ground cover, must be overcome. The effect of cultural treatments on the growth of three commercial pine species on reclaimed surface-mined land in southwestern Virginia was studied. In June, 1981, containerized seedlings of loblolly (Pinus taeda L.), Virginina (P. virginiana Mill.), and eastern white (P. strobus L.) pines were planted on a flat bench site (Site I) and a site returned to approximate original contour (Site I1). Seedlings were artificially inoculated with Pisolithus tinctorius ((Pers.) Coker and Couch), fertilized with slow-release fertilizer pellets at time of planting and broadcast with N fertilizer prior to the fourth growing season, and the ground cover around them was controlled with herbicides through the third growing season. Survival and growth of these seedlings after the first and second growing seasons were reported by Schoenholtz and Burger (1984). The response of these pines to treatments at the end of the third and fifth growing seasons were evaluated in this study. Treatment effects on foliar nutrient levels and soil properties were also examined. At the end of five years, loblolly and Virginia pines have been successfully established and are performing as well as trees in stands growing don natural soils in the southeastern U.S. Eastern white pine grows slowly the first three years and was just beginning to exhibit a response to treatment. Ground-cover control had the greatest effect on loblolly pine volume-index and elicited as much as an 86% increase in volume-index at the end of five growing seasons. Volume-index of Virginia pine was improved with ground-cover control on Site I and with fertilization on Site II. All species show an additive growth response to the combined treatments. At age five, white pine responded synergistically to combined fertilizer and ground-cover control treatments. The peak response to treatments occurred generally at age two for both loblolly and Virginia pines, while white pine response never peaked. The status of foliar and soil nutrients corroborated the importance of these cultural treatments in improving growth. Negative relationships between volume-index and foliar N and mineralizable N showed that N was not limiting pine growth at this time. Mature stands of serecia lespedeza may have supplied adequate N. A positive relationship between white pine volume-index and foliar P levels suggested that insufficient P may have limited growth of this species. As mine soils in this region age, soil P tends to be fixed by Fe-oxides present in the spoil, making competition for low levels of available-P even greater. Fertilization and ground-cover control will improve tree growth on reforested surface mines by alleviating complex interacting water and nutrient deficiencies. These treatments, implemented during establishment, were still evident at age five, a time that coincides with bond-release eligibility, and response curves suggested that response to treatments will continue as the stands develop. / Master of Science

Several nonlinear, individual tree crown height increment equations were tested for their ability to predict annual crown height increment in loblolly pine plantations. The selected model contained tree height (HT), tree crown ratio (CR) raised to the one-half power, age (A), and a competition index (CI) for the distance-dependent model and the ratio of quadratic mean diameter to tree dbh (DR) for the distance-independent model. The distance-dependent and the distance-independent models were the same form, except for the expression for competition. Hypothesis tests revealed that thinning, both its intensity and the elapsed time since its occurrence, had a significant effect on crown height increment. A thinning variable, THIN1, which accounted for thinning intensity and the interval since thinning, was developed and incorporated into the final individual tree increment models. Predictions of crown height increment were improved using models with the THIN1 variable as compared to those with no thinning allowance. In another approach, existing crown height equation was modified to account for the effect of thinning on crown recession. Another thinning variable, THIN2, similar to THIN1, was added to the crown height model. This model yielded better results than its counterpart with no thinning variable; however, the improvement was not as great as for the increment models. The individual tree increment models were also used to form a stand level crown height increment model. The independent variables were collapsed to stand-level statistics; the final model contained average height of dominants and codominants (HD), average crown ratio (R), age (A), and the THIN1 variable. Unlike the individual tree models, raising the average crown ratio to .5 did not improve the fit; however, including THIN1 did improve the results. From this study it was concluded that better data, a standard definition of height to the live crown, and other crown variables, such as crown diameter, will be required to produce more refined individual tree crown height increment models. / Master of Science

In this thesis the five equation system of growth and yield equations originally developed by Clutter (1963) is examined. The system is redeveloped algebraically to form a truly algebraically compatible system. Three methods of estimating the coefficients were examined. In the first method, three of the equations were fitted independently using ordinary least squares; these coefficient estimates were carried through to the other equations. No consideration was given to the relationships that must exist between the equation coefficients in order for the system to be numerically consistent. In the second method the system is first developed algebraically, before any of the coefficients are estimated, resulting in a slightly different system which is truly algebraically compatible. The coefficients were estimated by fitting two of the equations, and using these estimates throughout the rest of the system. The resulting system is both numerically consistent and algebraically compatible. In the final method the relationships between the coefficients that must hold for the system to be compatible were incorporated in the coefficient estimation procedure. Seemingly unrelated regression techniques were used to estimate the coefficients. The three methods resulted in coefficient estimates that were similar, with seemingly unrelated regression producing the most efficient estimators. Prediction ability of the three methods on independent data show no method as being superior, although the seemingly unrelated regression procedure was able to reduce the total system error best. / M.S.

Annosus root rot caused by the fungus Heterobasidion annosum (fr.) Bref., causes a destructive root and butt rot of many important tree species throughout the world. Presently, methods for determining disease incidence and severity and destructive. In this study, the most effective, non-destructive, disease severity prediction parameters were determined for thinned Pinus taeda plantations growing on high hazard sites. Above-ground tree parameters and 0.03m³ soil-root (SR) samples were used as predictions variables. Base-line data for predictions was obtained by excavations of 190 tree root system from plantations located in Eastern Virginia and Central Alabama. Multiple regression analysis indicated that stem diameter (DBH), radical growth (GR5) live crown ration (LCR), and SR samples were the most effective parameters in explaining the variation in the root sustem colonizatio levels of the plot trees studied. / M.S.

The minimum number of tree heights that are necessary, with a probability of 0.95, to obtain a merchantable plot volume estimate of loblolly pine within ± 3, 5, and 10% of the volume observed if all plot trees had been measured for height were determined for all combinations of volume estimation techniques and sample designs examined in this study. The volume estimation techniques examined in this study were: 1) a volume equation using measured tree diameters and either measured heights or height estimates obtained from a plot height-diameter relationship, 2) a volume equation using strata average diameter and average height, and\ 3) a strata volume/basal area ratio estimator. The examined sampling designs were: 1) a simple random sample, 2) a stratified random sample, 3) a stratified systematic sample, and 4) a purposive sample. Both combined and separate stratified estimators were used for volume estimation techniques 2 and 3 when a stratified sample design was used. Of all the possible combinations of volume estimation techniques and sample designs, two combinations, volume estimation technique 1 and a stratified random sample, and volume estimation technique 1 and a purposive sample, are the only combinations that have sample sizes of no more than 30 trees for all three accuracy levels and require the smallest or nearly the smallest number of sample tree heights at these accuracy levels. / Master of Science

The study dealt with developing methodologies for predicting basal area distributions and individual tree basal areas. Data for the study was from the Hill Farm Experiment Station at Homer, Louisiana. Five height-diameter (basal area) curves were examined to determine which was most appropriate for the data set utilized. The model H = a + b log(BA), where H denotes height and BA denotes basal area, was chosen as best, based on several fit and prediction oriented statistics. A stochastic basal area distribution model, called the parameter distribution model, was developed. The model was based on the Chapman-Richards growth curve. This curve was fit to all stems on approximately 3/4 of the data set. Two parameters of the curve were fixed a priori, leaving two parameters to be estimated. A sampling distribution was fit to the estimates of the rate parameter, k. Models were developed to predict the parameters of this distribution from stand variables. A model was then derived to predict m, the shape parameter of the C-R curve, from k and stand variables. Finally, an existing survival function was modified. The overall model was implemented as follows: first, the number of surviving stems was predicted. Then k and m values were predicted for each predicted stem. Substitution of these two values into the C-R curve yielded a predicted basal area for each stem. The previously mentioned height diameter curve was employed to predict a height for each predicted basal area. Stochastic elements were built into the prediction model for m and the height-diameter curve. Predicted basal area and height distributions were compared to observed on the remaining 1/4 of the data set. Although the two--sample K-S test was statistically significant, the observed and predicted distributions did appear to be close, in general, from a practical standpoint. This approach appears promising as a stochastic method of predicting size distributions. The Chapman-Richards curve was also modified for use as an individual tree basal area growth model. Two parameters of the curve were fixed, and the remaining two were modelled as functions of tree- and stand-level variables. The modified growth function fit the data well, but on an independent data set, a simpler linear model of basal area growth performed better in terms of mean difference and mean absolute difference between observed and predicted basal areas. Thus, the only anticipated use of the modified C-R model is in situations where extrapolation beyond the range of observed data is required, since this model has desirable long-term characteristics, whereas the linear model does not. / Ph. D.

An integrated system of stand models was developed for loblolly pine in which models of different levels of resolution are related by a unified mathematical structure. A “telescoping'' system is presented in which a highly detailed overall model is specified and its components. ''collapsed" around a common set of growth and survival functions to provide structurally compatible models at each successively lower stage of resolution. The most detailed model is a distance dependent individual tree model which simulates the growth and competitive interaction of trees in a stand. Tree basal area and height growth were modeled using a modified Chapman-Richards function in terms of potential growth, current size, relative size, crown ratio, and an index of competition. Potential growth was considered a function of site quality, age, and open-grown size relationships. Tree survival probability was described using a logistic function in terms of age, crown ratio, and competition. The competition or point density index is a function of the size and location of neighbors. Published indices were evaluated and compared on their simple correlation with growth, multiple correlation with growth in the presence of other tree and stand measures, computer execution time, and relationships to stand level density measures. The area potentially available (APA) for each tree was chosen as the most suitable. The APA index is calculated as the area of the polygon constructed from lines which divide the distance between a tree and its neighbors. Mean APA, or average area per tree, is estimated by the inverse of trees per unit area, permitting point density to collapse to stand density, resulting in a distance independent individual tree model. This model was collapsed dimensionally to consider trees grouped in size classes. Tree growth and survival equations are applied to the mean attributes of each size class, resulting in a size class projection model. At the lowest level of resolution, the dimensions of the model are collapsed to one "average" tree. A stand level projection model results from applying the tree growth and survival equations to the stand's average tree attributes. At the stand level, the basal area growth function provides a transformation which, for a number of probability density functions (pdf's), will regenerate the initial pdf family. Considering a normal pdf to describe basal area distributions, a pdf-based size distribution model is presented, in which the projected parameters are expressed in terms or the growth function coefficients. Applications to other pdf families are discussed. Preliminary tree growth and survival equation coefficients were estimated using data from a loblolly pine stand density study in North Louisiana. Structurally compatible models at each level of resolution are detailed. Considerations for numerically consistent estimates from models of different levels of resolution are discussed in terms of model specification, estimation, and implementation. Recommendations for model application and future model development are presented. / Ph. D.

Nitrogen is the most frequently limiting nutrient in southern pine plantations.  Previous studies found that only 10 to 25% of applied urea fertilizer N is taken up by trees.  Enhanced efficiency fertilizers could increase tree uptake efficiency by controlling the release of N and/or stabilize N.  Three enhanced efficiency fertilizers were selected as a representation of fertilizers that could be used in forestry: 1) NBPT treated urea (NBPT urea), 2) polymer coated urea (PC urea), and 3) monoammonium phosphate coated NBPT treated urea (MC NBPT urea). Urea, MC NBPT urea, and NBPT urea fertilizer treatments showed an extractable NH4+ spike 14 days after fertilization while the polymer coated urea showed a spike in NH4+ 49 days after fertilization. Total ecosystem recovery of fertilizer in each treatment was; MC NBPT urea, 51.29 g N; NBPT urea, 48.87 g N; urea, 45.09 g N; and PC urea, 31.30 g N which represents 78.7%, 74.7%, 72.1%, and 47.6% respectively of the total N applied.  For the MC NBPT urea, NBPT urea, and PC urea treatments the largest sinks for N were the forest floor and mineral soil.  The largest sink for fertilizer applied N in the urea treatment was in the tree.  The 2011 foliage cohort was the largest sinks for fertilizer N recovered by the tree.  N volatilization was around 20% for all fertilizer treatments except polymer coated fertilizer, which was 1.1%.  Urea preformed the same as the soluble enhanced efficiency fertilizers and better than the PC urea fertilizer.  The results emphasize the importance of climatic conditions on fertilizer release and effectiveness. / Master of Science