Vegetation Variability and Its Hydro-Climatologic Dependence
White, Amanda Beth
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Permalink
https://hdl.handle.net/2142/83286
Description
Title
Vegetation Variability and Its Hydro-Climatologic Dependence
Author(s)
White, Amanda Beth
Issue Date
2005
Doctoral Committee Chair(s)
Kumar, Praveen
Department of Study
Civil Engineering
Discipline
Civil Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Plant Physiology
Language
eng
Abstract
The goal of this research is to investigate the multi-scale variability of vegetation, its dependence on hydrologic controls such as topography, soil properties, vegetation type, and climate variations (e.g., the El Nino Southern Oscillation [ENSO]), and to synthesize this understanding for future predictive modelling applications. The initial phase of this study examines how topographic variability moderates the climatologic influence on the vegetation at the inter-annual time-scale. The focus of the initial phase of the analysis is on the continental U.S. to gain insight into general, broad-sweeping relationships, yet focusing on particular ecological regions that have greater amounts of vegetation variability allows further insight into the influential mechanisms linking vegetation, climate, and physiography at small scales. Therefore, the Blue Ridge, Central Basin and Range, and Northern Rockies Ecoregions (CEC/EPA Level III Ecoregions), which exhibit large inter-annual vegetation variability, are chosen as the focus of the second phase of the current research. These ecoregions represent areas with complex terrain, minimal anthropogenic influence, and have varying climates, soils, and land covers, and the objective is to identify and analyze the dominant influences on the vegetation greenness across the varying environments in the three ecoregions. Regression tree induction is employed and a relevance index is developed based on the generated regression trees to examine the spatio-temporal variability of the controls on the vegetation growth. Within each ecoregion, cohesive areas are found where the vegetation dynamics differ from the surrounding areas, and in comparing these areas with the next-smaller scale ecoregions (EPA Level IV Ecoregions), similarities and differences are observed. Comparing across the ecoregions, the dominant controls on the vegetation growth are: the topographic influence in the Blue Ridge, the meteorologic influence in the Northern Rockies, and the land cover in the Central Basin and Range. This research advances our general understanding of multi-scale vegetation dynamics, as manifested through its dependence upon physiographic attributes and its relation to land-atmosphere processes such as the water cycle and climate oscillations.
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