Title page for ETD etd-04302005-191841


Type of Document Dissertation
Author Neatrour, Matthew Aaron
URN etd-04302005-191841
Title Factors affecting root system response to nutrient heterogeneity in forested wetland ecosystems
Degree PhD
Department Biology
Advisory Committee
Advisor Name Title
Golladay, Stephen W. Committee Co-Chair
Jones, Robert H. Committee Co-Chair
Burger, James A. Committee Member
Nilsen, Erik T. Committee Member
Webster, Jackson R. Committee Member
Keywords
  • root proliferation
  • root foraging
  • nutrient heterogeneity
  • forested wetlands
Date of Defense 2005-04-21
Availability unrestricted
Abstract
Soil nutrients are often heterogeneously distributed in space and time at scales relevant to individual plants, and plants can respond by selectively proliferating their roots within nutrient-rich patches. However, many environmental factors may increase or decrease the degree of root proliferation by plants. I explored how soil fertility, nitrogen (N) or phosphorus (P) limitation, and soil oxygen availability affected root system response to nutrient heterogeneity in forested wetland ecosystems of southeastern United States. Fine root biomass was not correlated with soil nutrient availability within wetland ecosystems, but was related to ecosystem-scale fertility. Root systems generally did not respond to P-rich patches in both floodplain (nutrient-rich) and depressional swamps (nutrient-poor) swamps, but results were inconclusive because the growth medium (sand) potentially hindered root growth. In floodplain forests, roots proliferated into N-rich patches but not P-rich patches, even though litterfall N:P ratios were > 15, which suggested that these ecosystems were P-limited. The combination of nutrient and oxygen heterogeneity affected root proliferation and biomass growth of three common floodplain forest species (Liquidambar styraciflua, Fraxinus pennsylvanica, and Nyssa aquatica) in a potted study, which was related to species’ flood tolerance. My results suggest that the environmental context of plants can affect roots system response to nutrient heterogeneity in forested wetland ecosystems and highlights the need for field studies that investigate this phenomenon. Learning how environmental conditions affect plant response to nutrient heterogeneity at a fine-scale will provide better predictions of nutrient cycling, plant competition and succession, and forest productivity, which are important factors that determine carbon sequestration and timber production.
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