Loblolly pine (Pinus taeda) plantations are a common land use of the southeastern United States that have the potential to function as a source of cellulosic biomass for biofuel production. A novel land use practice of intercropping switchgrass (Panicum virgatum) between planted loblolly pines has been developed as a potential method of cellulosic biomass production. I evaluated response of arthropods and breeding birds to intercropping switchgrass within loblolly pine plantations compared to typically managed pine plantations. I detected 13 arthropod orders and 44 breeding bird species during 2014 – 2015. Intercropping switchgrass reduced arthropod diversity and evenness, with richness not affected. Arthropod abundance response to intercropping switchgrass varied among orders. Breeding bird species did not respond differently to intercropping switchgrass compared to typically managed pine. Continued assessment is needed to provide greater insight regarding potential effects of this land use practice throughout a rotational period.

As forests change, tree physiology responds to changes in resource demands. The impact of Pinus taeda (loblolly pine) mortality on physiology of successional hardwoods is unknown. Liquidambar syraciflua (sweetgum) and loblolly pine individuals were measured for resource-use during a simulated southern pine beetle mortality event where several pines underwent a girdling treatment. Sweetgum next to untreated pines had significantly higher sapflow every month, markedly throughout post-mortality months. Sapflow and photosynthetic capacity significantly declined in girdled pines before needle discoloration. Nitrogen concentration of senesced pine and sweetgum leaves significantly increased from pre-mortality to post-mortality. Pine mortality led to increases in sweetgum water use and leaf nitrogen content. A shift in species dominance from loblolly pine to sweetgum would reduce water lost by pine transpiration during sweetgum dormancy by approximately 154 mm. These data indicate significant responses to disturbance and seasonal resource demands in this forest type.

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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 162-167). Also available via the Internet.

Thesis (Ph. D.)--Biology, Georgia Institute of Technology, 2008. / Committee Chair: Cairney, John; Committee Member: Merrill, Alfred Jr.; Committee Member: Nichols, Wylie; Committee Member: Pullman, Jerry; Committee Member: Streelman,Todd.

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008. / Committee Chair: Dr. Sheldon May; Committee Member: Dr. Donald Doyle; Committee Member: Dr. Gerald Pullman; Committee Member: Dr. James Powers; Committee Member: Dr. Nicholas Hud.

Belowground competition presents a threat to the production and sustainability of tree-grass ecosystems. Management scenarios designed to optimize the spatial and temporal distribution of soil resources will improve resource-use efficiency and promote greater co-production. We conducted three experiments to assess competition dynamics between loblolly pine and switchgrass. In a three-year field trial, loblolly pine and switchgrass were intercropped across varying competitive intensities. Interspecific competition decreased loblolly pine annual growth; however, establishing vegetation exclusion zones surrounding pines largely mitigated these effects. Switchgrass yields were less affected by interspecific competition compared to pines and land equivalency ratios indicated that with proper management co-production yields may exceed those of switchgrass monoculture. Switchgrass was a constant and significant competitor across all years while loblolly pine resource use was minimal in year 1 but increased in subsequent years. In a short-term greenhouse experiment, native soil was amended with biochar and inorganic N fertilizer and the effects of these amendments upon soil properties and switchgrass productivity were assessed. Biochar increased soil pH, total soil carbon, and soil moisture. However, N fertilization had negligible effects upon soil properties. Plant response to biochar was neutral to negative while N fertilization increased switchgrass foliar biomass but no interactive effects of the amendments were observed. Although the effects of biochar upon switchgrass production were trivial, its positive influence upon soil properties suggests a potential for mitigating competitive interactions. Finally, a field-scale study examined co-production of loblolly pine and switchgrass over two years in response to competition control, biochar, and N fertilizer. As expected, interspecific competition reduced soil resources and decreased plant productivity. Biochar increased total soil C and soil moisture levels but had relatively minor impacts upon other aspects of soil fertility or plant production. Nitrogen fertilization acidified soil pH and decreased total soil C and N but positively affected loblolly pine foliar N concentrations and switchgrass yields. A positive association between soil inorganic N and switchgrass yield suggests the species competitive influence may be increased with greater N supply.