Southeastern coastal plain pine savannas lack direct evidence of past fire regimes. As a result, uncertainty exists regarding the range of variation in frequency and seasonal timing of past fire regimes and the relative importance of anthropogenic and lightning-ignited fires. Characterization of past fire regimes is needed for effective restoration and management of these high-biodiversity ecosystems. I used dendrochronologically dated fire scars from stumps of old growth longleaf pines in a large coastal, mainland pine savanna and from dead slash pines on a small, coastal barrier island in north Florida to explore past fire regimes. In the mainland savanna, 71 different fires occurred from 1592-1883, based on a composite record of 109 fire scars from six fire-scarred trees. Almost all (95%) scars occurred during the middle growing season. Only three fires, all in the 1800s after European settlement of the local area, occurred during the dormant season. There was a 2-3 year fire return interval between 1679 and 1868. Variability in fire return intervals was low, with 92% of all fires occurring at < 5 yr intervals. On the barrier island 159 fire scars occurred in 21 separate years from 1864-2000, based on a record of 52 pines scarred during turpentine operations. Two periods of no fire scars corresponded to times of active pine resin extraction on the island (1911-1918, 1948-1958). Mean fire return intervals averaged four years from 1864-1910 and 1919-1947. A longer nine-year fire return interval occurred from 1959-2000. Most (86%) fires recorded in scars occurred during the growing season. The very high frequencies of growing season fires recorded in annual rings of these trees indicate that fire regimes were primarily driven by synoptic climatic conditions rather than by cultural burning practices. Both sites recorded frequent, growing season fires, suggesting that lightning fires were occurring frequently both before and after settlement despite differences in size and landscape context. This direct evidence of fire history in southeastern pine savannas can resolve some outstanding questions regarding ecological fire management. Fire managers now have direct evidence that supports frequent, growing season fires in pine savanna.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Plant Biology." Includes bibliographical references (p. 161-166).

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Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Plant Biology." Includes bibliographical references (p. 145-148).

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Plant Biology." Includes bibliographical references.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Plant Biology." Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Plant Biology." Includes bibliographical references (p. 44-46).

Thesis (Ph. D.)--Oklahoma State University, 2005. / Vita. Includes bibliographical references (p. 221-228).

Recent anthropogenic activity in south Florida has increased inputs of phosphorus being delivered to the historically oligotrophic Everglades. Consequently, understanding how phosphorus structures these wetlands is critical. I investigated this with both indirect, correlative techniques and direct, experimental manipulation in two community types: sawgrass and wet prairie. Composition, abundance and productivity in the sawgrass community is most likely controlled primarily by P-availability. In contrast, controls of structure in the wet prairie seem to vary among species and include both P-availability and hydrologic regime. These two communities also respond differently to nutrient enrichment. While the sawgrass community appears to store newly available P in the form of increased production, the wet prairie seems to rapidly recycle P through increases in aboveground turnover rates. As part of my research, a nondestructive technique which accurately estimates aboveground live standing crop in eight common Everglades species was developed.

Human society has benefited greatly from plant secondary metabolites, often utilizing a variety of compounds as dyes, food additives, and drugs. In particular, pharmaceutical development has benefited greatly from plant secondary metabolites. One example of this utility is paclitaxel, a highly substituted diterpene approved in the treatment of breast cancer, ovarian cancer, non-small cell lung cancer, and the AIDS-related Kaposi’s sarcoma. Demand of paclitaxel is likely to increase, due to the current examination of paclitaxel in numerous clinical trials against a variety of other cancers. Taxus cell culture represents a production source of paclitaxel to meet future demand. However, paclitaxel production through Taxus cell culture is often variable and low. Targeted metabolic engineering of Taxus to produce superior paclitaxel-accumulating lines is a viable strategy to address variable and low yields. To facilitate the production of genetically engineered Taxus cell lines, stable transformation is required to examine the long-term effect of gene expression in vitro. Additionally, suitable transient transformation systems are necessary to characterize novel Taxus genes related to paclitaxel accumulation. A transient particle bombardment-mediated transformation protocol was developed to introduce transgenes into Taxus cells in vitro. Additionally, agroinfiltration in Nicotiana benthamiana was examined as a system to express genes related to paclitaxel biosynthesis and lead to the accumulation of the first dedicated taxane, taxa-4(5), 11(12)-diene. In regard to stable transformation, an Agrobacterium -mediated transformation protocol was developed, though this method requires further optimization for reliability and increased transformation efficiency. These transformation technologies will aid in the creation of elite paclitaxel-accumulating Taxus cell lines.