Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 71-72). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 79-82). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 63-66). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 92-95). Also available via the Internet.

Effects of thinning, such as increased diameter growth and decreased mortality in the residual stand, have been recognized by foresters for many years. These effects are largely the result of increased tree vigor which is induced by a decreased level of competition. These relationships are reflected in many of the models that are central to PTAEDA2, a growth and yield simulator which was developed for use with loblolly pine (Pinus taeda) plantations established on cut-over, site prepared lands. Data from a long-term thinning study served as a basis for attempting to improve the predictive output of PTAEDA2. Assessment of differences in model parameter estimates between three levels of thinning intensity led to various approaches to reach this goal. Height increment and mortality models were found to need no additional refinement and were re-fit using all available data. Diameter increment and crown ratio model forms could not account for thinning effects in their present form and thinning response functions that could provide the proper behavioral response were added to these models.Models were evaluated individually and in combinations in a reduced growth simulator. This reduced simulator is a modified form of the growth subroutines in PTAEDA2 and is designed to utilize external data. Results of growth simulation runs show improvements in predictive ability for the crown ratio model fit to all data and for the re-fit height increment model/crown ratio model with thinning response variable combination. The diameter increment model with a thinning response variable significantly improved diameter prediction within the simulator, but predicted stand volumes were poor. The re-fit mortality function resulted in greater prediction error for mortality than the original PTAEDA2 mortality function. / Master of Science

The influence of nitrogen supply on relationships of relative growth rate (RGR) to leaf physiology, structural and non-structural carbon partitioning, and nitrogen- and water-use efficiencies were examined in loblolly pine (Pinus taeda L.) clonal lines differing in growth potential. Nine 18-month-old loblolly pine clones were grown in a climate-controlled greenhouse for 20 weeks under two contrasting nitrogen (N) regimes (50 and 250 ppm) and a growth analysis was carried out. Higher nitrogen increased plant RGR and largely resulted in proportional shifts in biomass from roots and stems to needles. The RGR of plants receiving higher nitrogen was increased primarily through increased leaf area ratio (LAR), which was increased through higher leaf mass fraction (LMF) and not through changes in needle morphology. Although concentrations of needle glucose in plants receiving 250 ppm N were 22 percent higher than plants receiving lower N, total non-structural carbohydrate concentrations in needles of plants receiving 50 ppm N were nearly double that of clones receiving 250 pm N, primarily due to starch accumulation of the nitrogen-deficient plants. Plants receiving 250 ppm N also had 39 and 18 percent lower starch in the coarse and fine roots, respectively. Plants receiving higher nitrogen were also more water-use efficient, but had lower photosynthetic nitrogen-use efficiency. LAR, net assimilation rate (NAR), specific leaf area (SLA), and LMF were all positively correlated with RGR, but the main influence on RGR differences among clones was LAR. In addition, leaf-level rates of photosynthesis and respiration were positively correlated with RGR; however, faster-growing clones did not exhibit greater carbon economy at the leaf level. Both instantaneous water-use efficiency (A/E) and δ13C were positively correlated with RGR and photosynthetic nitrogen-use efficiency was negatively correlated with RGR. The identification of physiological and morphological traits underpinning differences in RGR among clones and how these traits are affected by nitrogen supply provides new information on trait correlations within species and parallels broader patterns observed among species.

The influence of nitrogen supply on relationships of relative growth rate (RGR) to leaf physiology, structural and non-structural carbon partitioning, and nitrogen- and water-use efficiencies were examined in loblolly pine (Pinus taeda L.) clonal lines differing in growth potential. Nine 18-month-old loblolly pine clones were grown in a climate-controlled greenhouse for 20 weeks under two contrasting nitrogen (N) regimes (50 and 250 ppm) and a growth analysis was carried out. Higher nitrogen increased plant RGR and largely resulted in proportional shifts in biomass from roots and stems to needles. The RGR of plants receiving higher nitrogen was increased primarily through increased leaf area ratio (LAR), which was increased through higher leaf mass fraction (LMF) and not through changes in needle morphology. Although concentrations of needle glucose in plants receiving 250 ppm N were 22 percent higher than plants receiving lower N, total non-structural carbohydrate concentrations in needles of plants receiving 50 ppm N were nearly double that of clones receiving 250 pm N, primarily due to starch accumulation of the nitrogen-deficient plants. Plants receiving 250 ppm N also had 39 and 18 percent lower starch in the coarse and fine roots, respectively. Plants receiving higher nitrogen were also more water-use efficient, but had lower photosynthetic nitrogen-use efficiency. LAR, net assimilation rate (NAR), specific leaf area (SLA), and LMF were all positively correlated with RGR, but the main influence on RGR differences among clones was LAR. In addition, leaf-level rates of photosynthesis and respiration were positively correlated with RGR; however, faster-growing clones did not exhibit greater carbon economy at the leaf level. Both instantaneous water-use efficiency (A/E) and δ13C were positively correlated with RGR and photosynthetic nitrogen-use efficiency was negatively correlated with RGR. The identification of physiological and morphological traits underpinning differences in RGR among clones and how these traits are affected by nitrogen supply provides new information on trait correlations within species and parallels broader patterns observed among species.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains ix, 113 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Thesis--Virginia Polytechnic Institute and State University. / Vita. Abstract. Includes bibliographical references (leaves 49-53). Also available via the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 224-238). Also available via the Internet.