M. S.

Ten clones of eastern white pine (Pinus strobus L.) representing three different pollutant sensitivity classes (i.e. sensitive, intermediate, and tolerant) were exposed to ozone, sulfur dioxide, and nitrogen dioxide singly, and in. combinations at various concentrations. Visible symptom expression, needle length, and needle dry weight of current year needles were determined weekly during long-term pollutant exposures. One clone of each sensitive class was selected to study the effects of long-term exposures with ozone, sulfur dioxide, or nitrogen dioxide on photosynthesis, transpiration, and dark respiration. Genetically controlled plant responses to pollutant exposures were found in all clones with various degrees of repeatability. A general plant sensitivity to all of the pollutants was not observed in test clones. Foliar symptom expression was only categorically differentiated among sensitivity classes but was not distinguishable in clonal response within the same class. At the end of long-term exposures, needle length was not significantly different among pollutant treatments. Good agreement was found among white pine gas exchange rates, needle dry weight, and chlorophyll content with respect to clonal sensitivity. Sensitive clone exhibited the greatest reduction in net photosynthesis due to ozone and sulfur dioxide exposures followed by intermediate and tolerant clones. Early stimulation of dark respiration was induced by ozone and sulfur dioxide exposures in sensitive clone followed by a dramatic: decrease at late stages of long-term experiment. Nitrogen dioxide at test concentrations did not.significantly reduce net photosynthesis, transpiration, and dark respiration rates. There was a correlation between clonal needle dry weight, chlorophyll content, and degree of its pollutant injury. Different modes of injury actions by different pollutants are proposed based upon presented data. Results support the concept that the ranking of plant sensitivity to pollutants could be varied with plant response chosen as indexing criterion. Presented data suggest that the adverse effects of pollutant exposures on white pine growth are primary due to inhibition of net photosynthesis, less chlorophyll content, and high respiration rate. Visible injury and needle length are concluded to be less superior than net photosynthesis, transpiration, dark respiration, chlorophyll content, and. needle dry weight measurement in providing reliable indexing. parameter for white pine pollution sensitivity prediction. / Ph. D.

This study examined shrinkage and related characteristics of two North American varieties of lodgepole pine: Pinus contorta var. latifolia and Pinus contorta var. murrayana, sampled at 10% of tree height. For var. murrayana, size was the only factor that had a significant effect on specific gravity; specific gravity decreased with increasing tree diameter. For var. Iatifolia, latitude was the only factor that had a significant effect on specific gravity; in general, specific gravity increased with increasing latitude. Conversely, specific gravity had a significant effect on radial shrinkage, the radial shrinkage tangential shrinkage ratio, and volumetric shrinkage for both varieties. The analysis of variance procedure indicated that the factors size, latitude, and elevation had no effect on the shrinkage of var. Iatifolia. However, for var. murrayana, radial shrinkage was affected by both tree size and latitude. Tangential shrinkage was also affected by latitude (increasing with increasing latitude). Linear correlations between radial shrinkage and growth rate, longitudinal shrinkage and distance I from the pith (a negative relationship), and specific gravity and growth rate were highly significant for both varieties. For var. Iatifolia, the linear association between specific gravity and heartwood percent was also significant. For var. murrayana, no difference in shrinkage or specific gravity was detected between the heartwood and sapwood. For var. Iatifolia, heartwood shrank less radially and had a lower specific gravity than sapwood. A comparison of the two varieties at their common latitudes indicated that murrayana trees have both higher specific gravity and shrinkage than do Iatifolia trees of the same size. / Master of Science

Although the research reported here has not satisfied its primary objective of a mathematical expression of diameter distributions in natural stands of Virginia pine, several constructive conclusions and recommendations are possible. All of them are offered with the perspective that research in the interest of advancing growth and yield techniques in forestry is needed, that the study has been exploratory to begin with, and that the contributions presented here, however conclusive or trivial, are the beginnings of a foundation for further research work. Certain deficiencies in the study are apparent, if not obvious. The major deficiency in the statement of the problem and its conclusion is the lack of a rigorous criterion, or criteria, for judging the success of a fitted distribution. Chi-square was used in this project to test the success of the model, but as the work progressed it became increasingly clear that chi-square was not the best criterion for the purpose of this work. It is the utilitarian purpose of the model that more aptly determines its success, for it is the ability to describe with sufficient precision the attributes of the forest stand that justly determines whether or not the model is useful. Therefore, Validation of the model should be connected with the forester's interest in volume, value, quality, cost estimation, return, profit and any other attributes useful in management of timber. / Master of Science

SPBMODEL, a legacy southern pine beetle (SPB) simulation model, was translated into a new JavaTM model called Javahog. The Javahog output was verified to be essentially identical to SPBMODEL output by means of standard and paired t-tests. Javahog was placed online and is currently accessible via a servlet. Genetic algorithms (GAs) were applied to the Javahog model. GAs are a type of optimization heuristic that operate as an analog to evolution. GAs "evolve" a very good solution to a complex problem. In this case, GAs were intended to evolve a very good version of SPBMODEL. GAs were applied in part to improve upon the SPBMODEL design, and in part to demonstrate that GAs are effective tools for recalibrating legacy simulation models. Beyond simply recalibrating model parameters, the GA was used to select optimal functional forms for the development rates of each SPB life stage. The GA evolved a model that performed better than SPBMODEL at predicting observed field data, according to a balanced fitness function and according to sums of squared errors. However, from a visual comparison of the output of both models versus observed field data, neither model achieved satisfactory performance. / Master of Science

The probability of mortality for an individual tree with certain characteristics growing under certain conditions was modeled. A particular algorithm SCREEN was used to fmd the best set of predictors variables. This algorithm was specially created to be used when the dependent variable can take only two values like in this binary case (dead or alive tree). The logistic model with different independent variables, which were found to be significant through the SCREEN algorithm, was fitted to the data. For the unthinned plots the logistic model with the following variables, CR (crown ratio), HH (total height/height of dominant and co-dominant trees) and CI (competition index) was compared with the survival model applied in a published distance-dependent model PTAEDA. The logistic model with CR, HH and DD (quadratic mean diameter/dbh) was compared with the survival model already used in a distance-independent model TRULOB. In both cases the behavior of the logistic model was quite similar to the published models. For the thinned plots the predictor variables DDt HH, CI and CR raised to 1.5 were used in the logistic model to predict mortality for individual trees. Mortality is difficult to predict. In this particular study the logistic model was used. The final distance-dependent model for unthinned plots includes as predictor variables CR, HH and CI. For thinned plots the final logistic model employs HH, CI and CR raised to 1.5 as independent variables. The final distance-independent model for unthinned plots includes as predictor variables HH, DD and CR. For thinned plots the final logistic model uses HH, DD and CR raised to 1.5 as independent variables. Differences between deterministic and the stochastic treatments of mortality were also studied. No practical differences in several stand characteristics such as average height, total volume, basal area were found when using these two approaches. Further, no significant differences were found in the diameter distribution for dead or alive trees. / Master of Science

The southern pine beetle (SPB) (Dendroctonus frontalis Zimm.) is one of the most destructive forest insect pests in the southeastern United States and has historically had a large impact on the forests of North Carolina. Many characteristics of a forest can contribute to SPB susceptibility including stand density, growth rate, age, soil type, and position on the landscape. This work was undertaken in an effort to assist and improve on the current federal SPB hazard modeling being conducted for North Carolina by the USDA Forest Service – Forest Health Protection's Forest Health Technology Enterprise Team (FHTET). In our study, predictive SPB susceptibility models were developed for each physiographic region in North Carolina using two variables not currently included in the FHTET modeling, mean stand age and the in-stand percentage of sawtimber-sized pines. These variables were obtained from USDA Forest Service – Forest Inventory and Analysis (FIA) data and North Carolina Forest Service historical SPB records creating a dataset of both infested and non-infested stands and the models were developed using the CART® classification tree approach. Two model-derived age classes (older than and younger than 22 years) were identified on the landscape using current Landsat 5 Thematic Mapper (TM) imagery chronosequences of disturbance index (DI) â transformed scenes to identify stand-replacing disturbances, resulting in a kappa statistic of 0.6364 for the younger than 22 year age class and 0.7778 for the older than 22 years age class. A kappa value of 1 is ideal. The CART® modeling effort produced valid models in all three physiographic regions of North Carolina, though the complexity of the piedmont model makes it impractical for use in the field. The dependent variable in the classification tree was presence or absence of SPB outbreak and the test sample error percentages were similar across regions, with errors ranging between 23.76 - 34.95 percent. Overall prediction success, based on the software's internal cross-validation procedure, was likewise comparable across the regions with 72.28 - 89.56 percent correctly predicted. Based on our modeling, stand age and percent sawtimber should be included in future FHTET SPB hazard modeling efforts for the coastal plain and mountains, respectively. Age classes can be reasonably estimated using Landsat or other multispectral imagery. / Master of Science

The initial physiological processes leading to enhanced growth of loblolly pine subsequent to fertilization are not clearly understood. Much of the debate revolves around the temporal response of photosynthesis (Pn) to fertilization or even if Pn increases at all due to enhanced nutrition. This study tracked loblolly pine light-saturated photosynthesis (Asat), dark respiration (Rd), volume, height, basal diameter, and leaf area responses in eight clones to fertilization (112 kg/ha N) over the course of a growing season in the field. Measurements were conducted intensively before and after fertilization in order to track the initial physiological changes prior to any changes in growth in the fertilized seedlings. The results showed that fertilization does increase Pn rates although there was no significant effect on Rd rates during the study. The fertilized seedlings mean Asat rates were significantly higher on three sampling dates and remained higher throughout most of the sampling period. At the end of the growing season, the fertilized seedlings had a 30.5% higher projected crown area than the controls and 48% greater mean volumes. Physiological and growth responses were significantly different among clones with some showing large and others showing little or no response to fertilization. These results support the hypothesis from Gough et al. (2004b) that post-fertilization increases in Pn create extra photoassimilate used in building larger leaf areas. These larger leaf areas contribute to higher canopy photosynthesis levels, which leads to an increase in dry matter production. / Master of Science

The anatomical properties of loblolly pine (Pinus taeda L.) and cottonwood (Populus deltoides Barto ex. Marsh.), both from intensively managed woodlands, were quantitatively characterized using the principles of stereology. Physical and mechanical properties were also determined for each growth increment of six sample trees of both species. Anatomical parameters measured were correlated to certain mechanical properties. The numerical values obtained for the anatomical properties were derived from simple counting measurements. They included size distribution parameters of individual anatomical elements as viewed on transverse sections. The parameters were determined both in terms of within growth ring variability and in terms of changes from pith to bark within the species studied. Average mechanical properties of the two species were shown to increase significantly from pith to bark. In the regression models constructed for predicting physical and mechanical properties, up to three anatomical variables were found to significantly account for the variation in the strength properties. Close to 87% of the variation in MOR and 86% in MOE could be accounted for by the three anatomical parameters in loblolly pine. About 82% of the variation in the crushing strength parallel to grain could be explained by the anatomical variables. The three anatomical parameters selected for predicting strength properties in cottonwood were all related to fibers, suggesting that the most important anatomical elements determining strength in cottonwood are the fibers. Overall predictability in cottonwood was not as good as in loblolly pine. Less than 40% of the variation in MOR could be explained by fiber properties alone, while almost 70% in MOE was accounted for. Over 55% of the variation in maximum compression strength parallel to grain could be explained by fiber properties alone. About 84 to 94% of the variation in specific strength properties was accounted for by three anatomical variables unrelated to specific gravity in loblolly pine. Addition of specific gravity improved the model with R² values between 92-97%. In cottonwood, 65-85% of variation in specific strength properties was accounted for by three anatomical variables unrelated to specific gravity. The R² values also improved by addition of specific gravity (82-92%). / Ph. D.

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