Ph. D. / incomplete_metadata

Root growth potential CRGP) is the measure of seedling ability to grow new roots. Loblolly pine (Pinus taeda L.) seedlings from 5 seedlots were raised at two widely separated nurseries (Summerville, SC and New Kent, VA). In Experiment I, RGP was determined during the fall and winter of 1984-85 and 1985-86, and several morphological traits were measured. In Experiment II seedlings from the same seedlots were lifted during February 1985 and 1986 at both nurseries, and cold stored until subsequent outplanting; subsamples of outplanted seedlings were used for RGP determinations. Root growth potential varied significantly by family, nursery, and lift date, and first order interactions were significant. Generally, the RGP of Summerville raised seedlings was higher than that of New Kent raised seedlings. RGP was not strongly correlated with common measures of shoot morphology, but RGP was consistently well correlated with lateral root dry weight. In Experiment II, RGP varied significantly by family, nursery, and storage duration. The family x nursery effect was the only significant interaction. Summerville raised seedlings had higher RGP on each planting date. During each year RGP declined rapidly in storage. First year survival was significantly correlated with RGP (r = .52, p < .001). Height increment and RGP were also strongly correlated (r = .80, p < .001). These relationships and their implications for nursery management were discussed. / M.S.

The influence of thinning at age eight on the photosynthetic rate, needle conductance, xylem water potential, water use efficiency and growth of loblolly pine trees was studied during their ninth and tenth growing seasons. Litterfall dynamics were monitored throughout the study period as well. At the end of the second post-thinning growing season, trees in thinned plots had greater stem diameters, greater live crown ratios, greater live crown diameters and greater average volumes and basal areas than did trees in control plots. Significant physiological changes due to thinning were observed only in the lower crowns where needles were found to adapt to the sudden increase in available light by adjusting their physiology to resemble that of sun needles. Lower crown photosynthesis and needle conductance in thinned plots were more similar to upper crown values for these parameters than to lower crown, control plot values. Foliage produced during the current year and measured after full elongation had a higher average photosynthetic rate, needle conductance and lower average water potential than did foliage in its second growing season during both 1988 and 1989. Additionally, the water use efficiency of current-year foliage was significantly greater than that of the second-year foliage. In both thinned and control plots, significant diameter growth and photosynthesis continued throughout the dormant season although at a slower rate than during the growing season. Litterfall timing did not differ between thinned and control plots, nor did the amount of litterfall per unit basal area during the first year following thinning. Partial second-year data suggest that subsequent litterfall amounts will mirror the greater average crown size in thinned plots. / Master of Science

Although there remains some controversy as to the benefits of individual tree growth and yield prediction models over stand-level models, individual tree models still have wide acceptance. A generalized thinning response variable which can account for the intensity of thinning, as well as the age of the stand at the time of thinning and the time elapsed since thinning, was applied to two existing models for loblolly pine (Pinus taeda) in cutover site-prepared plantations. A site index equation for predicting mean total height of dominant and co-dominant trees and a diameter increment model were developed to incorporate the thinning response variable. New fits of height increment and mortality functions to the available data were also completed. Separate mortality functions were fit to data from unthinned and thinned stands. The base models for this analysis were from the individual tree growth simulation model PTAEDA2. Evaluations for predictive ability of these models were done in a reduced version of the growth simulator which was modified to accept external data. The mean total height model had improved predictive ability over the original PTAEDA2 model for this variable. The diameter increment model produced no significant improvement in simulation comparisons. Fitting the two mortality functions to the multiple observation data resulted in the reduced predictive ability of the simulator compared to the original mortality model from PTAEDA2 which was fit to data from unthinned stands only. / Master of Science

We examined how fast- and slow-growing families (based on height at 10 years) of Pinus banksiana Lamb. are affected by a climate altered by CO$ sb2$ during their first growing season. Our primary objective was to evaluate the possibility that genotypes performing best under present conditions may not necessarily do best under projected warmer climate. Seedlings were grown for six months in two climatic environments (350 $ mu$L/L CO$ sb2$ x present temperatures and 700 $ mu$L/L CO$ sb2$ x 4$ sp circ$C warmer temperatures) and with 100 ppm and 5 ppm nitrogen. / The CO$ sb2$T$ sp circ$ environment had a significant effect on most biomass components of seedlings and water-use efficiency but not on height and other growth variables. The nitrogen fertilization was generally the most significant effect of the treatments for most growth variables. / All the families responded in a similar way to variations in the growing environments except for WUE. Family differences were more important for measurements of height and growth variables than for biomass components. The architecture of seedlings was also highly variable between families. Norm of reaction graphs were built for several growth variables to outline which families were overall most successful in an enriched CO$ sb2$T$ sp circ$ environment. Of the 15 families studied, four of them were classified as most successful in a projected high CO$ sb2$T$ sp circ$ climate.

No description available.

A system of loblolly pine growth and yield models was developed which used database files as input. Using database files as direct input created a compatible link between the growth and yield models and a Geographic Information System (GIS). Since growth and yield models can be used to update forest inventories and a GIS is a common method for maintaining forest inventory data, this compatibility provided a method to rapidly update past forest inventory records. This system was used to evaluate four different loblolly pine growth and yield models. The growth and yield models examined were: a whole stand, a diameter distribution - parameter prediction, a diameter distribution - parameter prediction, and an individual tree. Three different validation approaches were used to create fitting and validation data sets from permanent plot remeasurement data, and evaluate each of the four growth and yield models at varying projection periods. The periods used were zero, three, six, and nine years. Evaluations were based solely on the capability of each to model to predict merchantable volume. In terms of root mean square error of prediction, the individual tree and whole stand models performed superior than the diameter distribution models. At shorter projection periods the individual tree model performed better than the whole stand model, but the whole stand was superior at the nine year period. The parameter recovery models performed better for shorter periods than the parameter prediction model, but this difference diminished with longer periods. / Master of Science

Title from PDF of title page. / Document formatted into pages; contains 78 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: With increasing encroachment on natural communities by anthropogenic activity, it is important to understand the functions of natural ecosystems in an effort to conserve natural areas. A first-hand study of the population dynamics of South Florida Slash Pine (P. elliottii Engelm. var. densa) following a fire event provided insight to its recovery and dispersal following a fire. A natural fire (lightning-induced) occurred in the spring of 2000 at the T. Mabry Carlton, Jr. Reserve, Sarasota County, providing an opportunity to study aspects of slash pine in relation to fire. One objective of my research was to look at dispersal/recruitment conditions and slash pine dynamics in relation to fire. I looked at the varying degrees of tree mortality due to fire at different stands of slash pines. / ABSTRACT: I also looked at the stands in terms of stand composition and spatial arrangement of surviving adults. Finally, I studied how variable seedling establishment and survival was between stands. Few inferences could be drawn between fire and these individual analyses; however, all analyses revealed that at the scale of this study, pine flatwoods are patchy. I also looked at the dispersal of slash pines following a fire event. I modeled my research after Ribbens et al. (1994) and Clark et al. (1998), who took a phenomenological approach to dispersal modeling. This approach involved using distances between adults and seeds/seedlings and fecundity of adults to create dispersal models based on maximum likelihood estimates (MLE). I found that, while I could predict a model within acceptable parameters for most of the stands, more data was needed to predict models that better fit the data. / ABSTRACT: This finding, along with the fact that I recovered no seed data for analysis, suggests factors are contributing to dispersal and recruitment (e.g. cone-crop) that need to be accounted for in the future. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Growth responses to climatic variables of red pine (Pinus resinosa Aiton) and Norway spruce (Picea abies L. Karst) were studied at the Morgan Arboretum, near Montreal, in southern Quebec, Canada (45$ sp circ$ 25$ sp prime$ N, 73$ sp circ$ 57$ sp prime$ W; 15.2 m above sea level). The relationships between climatic variables and basal area growth were examined using linear and quadratic models. Current and previous year's climatic variables were tested separately and in combination using multiple regression models. The best models explained 82% and 85% of the total variance of the growth of Norway spruce and red pine, respectively. The growth of both species was more associated with evapotranspiration than precipitation. The growth of Norway spruce was best explained by the current year's annual evapotranspiration (43%), while the growth of red pine was more related to previous year's August evapotranspiration (33%) at our site. / The JABOWA model was used to predict tree growth in hypothetical climates which could result from global climate changes. Based on literature, five treatments were applied: normal, and increases of 1, 3, 5, and 10$ sp circ$C. Comparison between the last (1983-1992) and next (1993-2002) ten years growth showed no significant differences between species when temperature was normal or increased by 1 and 3$ sp circ$C, but significant differences between species were observed when the temperature was increased by 5$ sp circ$C. Both species declined when the temperature was increased by 10$ sp circ$C. We concluded that Norway spruce is more sensitive to increases in atmospheric temperatures than red pine at our site.

Summary: The future mass propagation of elite families of Pinus patula by cuttings is a realistic method of deployment if the short-term performance of cuttings and seedlings are confirmed at harvesting. This will impact significantly on the future outlook of forestry in South Africa as softwood yields are improved substantially through the introduction of material of high genetic value in commercial plantings. This, however, will require significant changes in future silviculture and other management practices as foresters and plantation staff learn to regenerate, maintain, and schedule the harvesting of cutting stands according to a different set of demands as a result of the change in plant type. Contrary to operational experience, cutting survival was similar to seedling survival in all field studies. This indicates that factors other than those that were studied and reported on, such as planting techniques, may be contributing to mortality. Also, due to the different root structure of cuttings they may be more fragile. The similar survival observed in these trials, therefore, may have been due to the close supervision given to the planting operations by the research staff. Although survival was similar, both plant types survived unacceptably poorly in the majority of studies with an average stocking of approximately 50% at one year. It is therefore anticipated that commercial stands will require several blanking operations in order to achieve an acceptable stocking in excess of 85% by the following planting season. The reduction in expected profitability as a result of blanking costs, delayed establishment, and the loss of improved genetic plant material, indicates that this is an area that still requires further research irrespective of what plant type is being planted. The pathogen, Fusarium circinatum, was commonly isolated from the planting stock before and after planting in two studies. Due to its virulent nature, it was assumed that mortality on the trees on which F. circinatum was isolated was principally due to this pathogen. At planting all plants were observed to be healthy and free of disease indicating that this pathogen maybe carried from the nursery to the field in a cryptic form, either inside or outside the plant tissue , which results in the death of the newly planted tree. In two field studies, where F. circinatum was commonly isolated, the application of Benomyl fungicide and to some extent the biological control agent Trichoderma harzianum at planting appeared to improve survival although this improvement was not significant. Laboratory studies, designed to determine alternatives to Benomyl fungicide, indicated that three fungicides (Octave, Folicur and Tilt), three sterilants (Sporekill®, Prasin®and Citex®) , as well as a biological control agent (T.harzianum), were all highly successful in controlling F. circinatum colony growth in vitro. It is recommended that these products undergo nursery testing , where the plant material is inoculated with F. circinatum spores, in order to test their efficacy and possible phytotoxicity in vivo before commercial application. Post-planting survival was also affected by site climate . Greater temperature extremes, as well as lower humidity and less rainfall resulted in poor survival. Plant dimension at planting was found to interact with site quality where it was a significant factor on a poor quality site. Optimal cutting dimensions at planting was a root collar diameter of 2.8 - 3.2 mm, and a stem height greater than 7 cm at planting for cuttings produced in cavities 90 ml in volume. Optimal seedling dimensions at planting were a root collar diameter of 1.8 - 2 mm, and a stem height of 10 - 15 cm for seedlings produced in cavities 80 ml in volume. In a separate study, plant morphological criteria influenced medium-term growth, where greater root mass and thicker cutting root collar diameters at planting improved field growth performance for seven years after planting. A greater root mass at planting was achieved by raising cuttings in containers that could support greater medium volume. From the study it was concluded that cuttings should be raised for an approximate period of 9 months in container cavities no smaller than 80 ml in volume and possess an oven-dry root mass of 0.3 - 0.5 g at planting. In addition to similar survival, the cuttings in this study grew either similarly to, or in some cases out-performed, the seedlings that were used as a control. Several other published studies indicate that hedge maturation poses the greatest threat to the success of softwood cutting deployment. This is especially true in clonal forestry and methods to maintain juvenility, such as cold storage of shoots and cryopreservation, require further research before clonal plantations of P. patula can be realised. In the studies carried out on family hedges in this report, the effect of donor hedge maturation was found to influence nursery management practice and the characteristics of rooted cuttings. The nursery data indicates that rooting efficiency, root system quality, and stem size and form, all decline with increasing hedge age particularly from two years after the date of sowing. A decline in root system quality was particularly apparent and was observed prior to a decline in rooting efficiency. If field trials indicate poorer performance from older hedges , it may be necessary to determine whether the causes are purely ontogenetic, morphological, or both before drawing final conclusions about hedge longevity. Until such results are known, it is recommended that P. patula cuttings should be propagated from seedling donors maintained as hedges , approximately 15 cm high, for a period not more than three years from the date of sowing. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.