Intercropping switchgrass (Panicum virgatum) between tree rows within young pine (Pinus spp.) plantations is a novel method to generate lignocellulosic biofuel feedstocks within intensively managed forests. Intensively managed pine supports diverse avian assemblages potentially affected by establishment and maintenance of a biomass feedstock. I sought to understand how establishing switchgrass on an operational scale affects bird communities within intercropped plantations as compared to typical intensively managed loblolly pine (Pinus taeda) plantations. I conducted breeding bird point counts, nest searching and monitoring, and coarse woody debris (CWD) surveys following establishment of intercropped switchgrass stands (6 replicates), traditionally-managed pine plantations, and switchgrass-only plots (0.1 km2 minimum) in Kemper Co., MS from 2011 to 2013. I found establishment of intercropping did not affect downed CWD, but reduced standing snags and green trees. I detected 59 breeding bird species from 11,195 detections and modeled nest survivorship for 17 species. Neotropical migrants and forest-edge associated species were less abundant in intercropped plots than controls for two years after establishment, and more abundant in year three. Short distance migrants and residents were scarce in intercropped and control plots initially, and did not differ between these treatments in any year. Species associated with pine-grass habitat structure were less abundant initially in intercropped plots, but converged with pine controls in subsequent years. Switchgrass monocultures provided minimal resources for birds. There was no evidence supporting an effect of intercropping on songbird nest survivorship. I found evidence for dominance of one species, yellow-breasted chat (Icteria virens), over another, indigo bunting (Passerina cyanea) in competition for nest sites, which illustrates how songbirds competing for nest sites can coexist in sympatry without the dominant species driving subordinate competitors to local extirpation. This dissertation, and related publications, are among the earliest research on wildlife response to intercropping. Forest managers implementing intercropping within pine plantations where vertebrate conservation is a management priority should be aware of potential changes to snag-utilizing species from reductions in green trees and snags. Songbird populations may lag behind traditional management for up to two years following establishment of switchgrass. Intercropping neither positively nor negatively affected songbird nest survival.

Interest in renewable energy and governmental mandates has motivated land managers to consider cellulosic feedstocks for bioenergy. I investigated plant community response to a system including switchgrass (Panicum virgatum) as a feedstock intercropped with loblolly pine (Pinus taeda). I estimated plant species evenness, richness, and diversity and biomass production, with emphasis on white-tailed deer (Odocoileus virginianus) forages. I detected 225 species in 2,220 1-m2 quadrats, and 7,495 biomass samples (96.4 kg dry weight) from 960 quadrats. Intercropping reduced plant species diversity, total non-pine tree biomass, and biomass of deer forages during switchgrass establishment. These effects were no longer apparent at treatment level two years after switchgrass establishment, except that deer browse and total deer forage biomass remained less in intercropped interbeds. Intercropping in managed pines may temporarily effect plant communities but further studies are needed to examine longer term effects and to quantify effects on nutritional carrying capacity for deer.

Application of biosolids as an alternative source of Nitrogen (N) is becoming a common silviculture practices on loblolly pine forest. However, little is known about how biosolids type, application rate, and timing affect forest floor and soil N availability in pine plantations. The objectives of this study were to determine the effect of different types, rates, and season of application of biosolids on forest floor and soil N. The study was established in a 17-year-old loblolly pine plantation in Amelia County, VA. Anaerobically digested (AD225), lime stabilized (LS225), and pelletized (Pellet225) biosolids and a conventional inorganic urea plus diammonium phosphate fertilizer (U+DAP225) were surface applied at a rate of 225 kg ha-1 based on Plant Available Nitrogen (PAN) between March 5th and 10th, 2006. Anaerobically digested biosolids were also surface applied at the rates of 900 kg PAN ha-1 and 1800 kg PAN ha<sup>-</sup¹ (AD900 and AD1800). Anaerobically digested biosolids at the rate of 900 kg PAN ha⁻¹ were also applied on November 5th, 2005 (AD900F). Surface application of different type of biosolids in a loblolly pine plantation increased soil N availability and mineralization when biosolids were applied at the permitted rate of 225 kg PAN ha⁻¹. Surface soil NH₄-N and NO₃-N availability and N mineralization was significantly different among biosolids type over time. N release from different type of biosolids depends on the initial inorganic N content, and N mineralization in biosolids. The average soil N availability and mineralization was significantly greater in the Pellet225 treatments than in all the other treatments. Soil N availability decreased in winter in all the treatments but remained generally higher than the control until the end of the second growing season. Nitrate-N concentrations in lysimeters were below water quality standard limits in all the treatments applied at the rate of 225 kg PAN ha⁻¹. Accumulation of N, C, and Ca in the forest floor was well correlated with the amount of biosolids applied on each treatment. The surface application of different type of biosolids had minimal impact upon total N and C in the mineral soil. Increasing application rates of anaerobically digested biosolids directly increased soil N availability and mineralization. Nitrate-N concentrations in lysimeters were above water quality standards limits during several months in the AD900 and AD1800 treatments. Significant differences in the forest floor total N, C and Ca were observed with increasing application rates of biosolids. Total C accumulation was significantly higher in the forest floor in the AD1800 treatment. However, we observed no effect on soil total C with increasing application rates of biosolids. We found that biosolids application during spring significantly increased soil extractable N, N mineralization, NO₃-N leaching, and total C in the mineral soil in comparison to the fall application. Fall application significantly increased NH₄-N leaching and soil extractable Ca. We observed no significant effect on ion exchangeable N measured on membranes, total N, C, Ca, and pH measured in the forest floor, and soil total N and pH in the mineral soil. Our results demonstrated that permitted surface application of biosolids at the rate of 225 kg PAN ha⁻¹ in a loblolly pine plantation increased surface soil N availability without increasing the potential for NO₃-N groundwater pollution. / Ph. D.

Extracellular matrix (ECM) modifications occur during plant growth, development, and in response to environmental stimuli. Key modulators of ECM modification in vertebrates, the extracellular matrix metalloproteinases (MMPs), have also been described in a few plants. Here, we report the identification of Loblolly pine (Pinus taeda) Pta1-MMP and its characterization during seed development and germination. The Pta1-MMP protein has the structural characteristics of other plant MMPs, and a recombinant protein (rPta-MMP) generated by using EST sequences for a seed-expressed MMP exhibits Zn2+-dependent protease activity, and is inhibited by the active site-binding hydroxamate inhibitor GM6001 and EDTA. The Pta1-MMP gene is expressed during embryo development, with transcript levels increasing from proembryo to early cotyledonary stage, then declining during late cotyledonary expansion and maturation drying. Protein extracts exhibited similar developmental-stage MMP-like activity. Seed imbibition in water facilited germination, which was stimulated by GA3 and inhibited by ABA. The timing of germination was mirrored by the presence of MMP-like protease activity in both water- and GA3-imbibed embryos. Pta1-MMP transcript levels increased in association with germination for both GA3- and water-treated embryos, in agreement with MMP-like activity. In contrast, by 10 days after imbibition, Pta1-MMP transcripts in ABA-treated embryos were at levels similar to the other treatments, although MMP-like activity was not observed. The application of GM6001 during Loblolly pine seed imbibition inhibited germination in a dose-dependent manner. Our results suggest that Pta1-MMP is required for ECM modification, facilitating the cell division and expansion required for both embryo development and germination. To our knowledge, this is the first report of an MMP in any gymnosperm and also its involvement in embryo development and subsequent germination. / Ph. D.

Varietal forestry may increase the productivity of loblolly pine (Pinus taeda L.) in the Southern United Sates. However, the effects of these genetic x environment interactions are still poorly understood. In this study we examined the responses in growth, stand uniformity and leaf level physiology of loblolly pine clonal varieties and families to silvicultural intensity and site effects. We also looked for patterns in observed traits that were consistent between crown ideotypes. Two varieties of each crown ideotype (narrow vs broad crowns) and two families (controlled mass pollinated (CMP) and open pollinated (OP) family) were tested on the Virginia Piedmont (VA) and the North Carolina Coastal Plain (NC) under different silvicultural intensities (operational vs intensive), and planting density (617, 1235 and 1852 trees per hectare). Data were collected during the first four growing season after establishment. At NC, intensive silviculture increased crown-width, height and dbh by 33%, 14%, and 23%, respectively. At VA, intensive silviculture increased crown-width, height and dbh by 41%, 10%, and 23%, respectively. Intensive silviculture also increased slightly but significantly the stand uniformity of stem growth. However, the differences in productivity between silvicultural treatments were not explained by differences in leaf-level physiology. Across all treatments and sites the varieties generally grew faster than the OP family, but the differences were higher at VA. Varieties did not differ in stem growth, but the broadest crown variety had greater stand uniformity, photosynthetic rate (Asat), carbon isotope discrimination (∆¹³) and lower fascicle size than the OP family. None of the traits assessed inthis study was consistent within the ideotypes. Varieties classified in the same crown-ideotypes may respond differently to the environmental effects of site and silviculture, which reinforces the need of matching varietal forestry with precision silviculture to achieve gains in productivity. / Ph. D.

This study was designed to investigate the development of the crown architecture of six genotypes of loblolly pine across a variety of growing conditions, and also to investigate the stability of the crown ideotype for these genotypes over a range of site and silvicultural management regimes. The objectives were to determine whether the crown dimensions that determine the crown ideotype of four clones, a mass-control-pollinated family, and an open-pollinated family of Pinus taeda L. are consistent within their respective genotypes, and to determine whether those same crown dimensions and genotypes follow consistent patterns even when established on different sites with contrasting qualities and different silvicultural regimes. The study was conducted on a 5-year-old plantation with an initial spacing of 1,235 trees per hectare. The plots had not reached crown closure, which provided the opportunity to assess the crown characteristics of individual trees of each genotype and how they developed over in a variety of growing conditions, without the interactions of other individuals. The study was a split-split plot design with the whole plot divided between two sites of contrasting quality; one site established in the Virginia Piedmont and a second site established in the North Carolina Coastal Plain. The sub plots were divided between high and low intensity silviculture. The sub-sub plots were divided among the six genotypes of loblolly pine. Seventeen tree and crown characteristics were measured, and means were compared using analysis of variance and Tukey's HSD test. We hypothesized that the branch and crown attributes would follow consistent patterns among these genotypes on the two sites and between the two silvicultural regimes. The results generally confirm these hypotheses. When the genotypes were compared, interactions only occurred with total branches, internode length, total foliage mass, and total leaf area. Tree height, diameter at breast height (dbh), stem volume, and crown volume averaged 4.8 m, 7.5 cm, 0.03 m3, and 7.1 m3, respectively at the site in Virginia, compared to values of 4.1 m, 6.2 cm, 0.02 m3, and 4.9 m3 at the site in North Carolina. Tree height, dbh, stem volume, branch diameter, branch length, and crown volume averaged 4.7 m, 7.5 cm, 0.03 m3, 1.3 cm, 90.3 cm, and 7.3 m3, respectively under high intensity silviculture compared to values of 4.3 m, 6.2 cm, 0.02 m3, 1.1 cm, 68.7 cm, and 4.7 m3 under low intensity silviculture. There were differences among the genotypes in branch diameter, branch length, and crown volume, with the branch diameter of clones 1 and 3 averaging 1.2 cm compared to an average of 1.3 cm for clones 2 and 4. Branch length for clone 1 averaged 72.4 cm and clone 3 averaged 77.0 cm, while branch length for clone 2 averaged 83.3 cm and clone 4 averaged 86.7 cm. Crown volume for clone 1 averaged 4.9 m3 and clone 3 averaged 6.3 m3, while clone 2 averaged 7.1 m3 and clone 4 averaged 7.2 m3. These differences conform to the crown ideotype for these clones, where clones 1 and 3 were considered narrow crowned and clones 2 and 4 were considered broad crowned. The branch diameter and branch length of the open pollinated family (OP) was similar in size to the broad crowned clones (1.3 cm and 84 cm, respectively), while the branch diameter and branch length of the mass control pollinated (MCP) family was smaller than the narrow crowned clones (1.1 cm and 71.2 cm, respectively). Crown volume for the OP family was intermediate between the clonal ideotypes, averaging 5.9 m3, while the MCP family had the smallest crown volume, averaging 4.7 m3. A single-degree-of-freedom ANOVA comparing the two clonal ideotypes yielded similar results. There were interactions with branch diameter, total branches, internode length, and total leaf area, but the broad crown ideotype was larger in every measured parameter than the narrow crown ideotype. The lack of interactions and the general conformity to crown ideotype in this study indicated stability among these genotypes across this variety of growing conditions. / Master of Science

Stand conditions influence the partitioning of biomass to stem, foliage, branch, and root components. Using data from 4 to 6-year old loblolly pine (Pinus taeda L.) trees grown in a miniature-scale spacing trial, this study determined the effect of initial planting density on the biomass partitioning of loblolly pine. An analysis of covariance concluded that density did not have a significant effect on the relative amount of biomass in aboveground components.Some measures of partitioning tradeoffs (such as root: shoot ratio) showed a significant positive slope when regressed against trees per hectare. Systems of linear equations were developed based on tree measurements and age, and additivity was specified. By taking into account contemporaneous correlations among tree components, seemingly unrelated regression (SUR) methodologies led to efficient parameter estimates. When compared to studies with mature trees at operational scales, results from the miniature-scale trees showed similar trends. Stem and woody roots were 70 and 14% of total mass, respectively. Since these miniature-scale trees were physiologically young at time of harvest, allocation of mass to foliage continued to be a priority, occupying 10% of total mass. / Master of Science

Biosolids, materials resulting from domestic sewage treatment, are surface applied to forest soils to increase nutrient availability. Retaining streamside management zones (SMZs) can limit nutrient pollution of streams. We delineated 15 m SMZs along three intermittent streams in an 18-year-old Pinus taeda L. plantation. We applied biosolids outside the SMZ on one side of each of the streams maintaining the other side of the stream as control. We collected water samples from the three treated and six reference streams as well as from the perennial stream both upstream and downstream from the intermittent streams for 12 months following treatment. Along transects perpendicular to the treated streams, we collected overland flow samples, soil solution samples at 60 cm and extracts from ion exchange membranes (IEMs) placed in the surface soil. We found elevated nitrate concentrations outside the SMZ in the treated side soil solution samples, in which concentrations remained below 1.5 mg L-1. Nutrient concentrations outside the SMZ in treated side IEM extracts increased following biosolids application, returning to near control levels after one year. Nutrient concentrations in IEM extracts were not elevated adjacent to the streams. We observed elevated phosphorus concentrations adjacent to the stream in overland flow during one period on the treated side of the stream. Stream nutrient concentrations showed few differences downstream from the treatment with concentrations below 1.5 mg L-1. Our results indicate that a 15 m SMZ protected streams from nutrient pollution for the first year following biosolids application to adjacent forestlands. / Master of Science

Nitrogen deficiency is characteristic of many mid-rotation loblolly pine (Pinus taeda L.) plantations in the Piedmont region of the southeastern USA. Fertilization with urea is the most common method used to correct this deficiency. Previous studies show that urea fertilization produces a rapid pulse of available nitrogen (N) with only a portion being utilized by plantation trees. Controlled release fertilizers release available N more slowly over a longer period of time and therefore may result in greater uptake efficiency. The objective of this study was to compare Nitroform®, a urea-formaldehyde controlled release N fertilizer versus urea and a control by measuring the effects of the two fertilizer treatments on N availability and loss as: total KCl extractable-N, total ion exchange membrane-N (IEM-N), N mineralization, and N volatilization, in a mid-rotation loblolly pine plantation in the Piedmont of Virginia. In addition, mid-summer and mid-winter fertilizations were compared to assess fertilizer uptake as a function of season. After the summer fertilization, Nitroform&reg; significantly increased total KCl-extractable N, IEM-N, and N mineralization for two to three months over urea and the control. Three hundred times more N volatilized from urea than from controlled release Nitroform®. Interestingly, seven months after the summer application, the controlled release Nitroform® showed marked immobilization for three months while urea demonstrated greater N mineralization. After the winter application, fertilization with urea demonstrated greater soil inorganic N concentrations for two to three months over Nitroform®, very little N was immobilized, and volatilization was only 10 times that of Nitroform®. After summer and winter fertilizations, both fertilizer treatments significantly increased soil inorganic N concentrations and N volatilization over controls, however did not significantly increase N mineralization over controls when average response was tested over the entire sampling period. In addition to the fertilizer effects measured, a thinning only treatment was also incorporated into this study with soil N-availability indices compared to a control with no thinning or fertilization. The results from the thinning only treatment demonstrated no significant increases over the control in total KCl extractable-N, IEM-N, N-mineralization, or N volatilization when average responses were tested over the entire sampling period. / Master of Science

The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae), is a prime example of a bark beetle of high ecological and economical importance. As these bark beetles adapt to a changing environment, forest managers must continue to evolve management strategies to improve forest resilience to these pests. Herein, we examined the validity of phenological trap timing cues for the annual spring D. frontalis risk assessment survey and found the traditional use of flowering dogwood (Cornus florida) (Cornaceae) bloom occurred an average of 3 weeks after peak D. frontalis spring flight activity. We also examined the natal host influence on adult beetle host selection to explore a possible explanation for the lower occurrence of D. frontalis infestations in longleaf (Pinus palustris) vs. loblolly pine (Pinus taeda) (both Pineaceae). The laboratory choice tests performed showed no selection preference based on natal host.