Saturday, 15 July 2006

Quantitative Assessment of Pedo-Biological Patterns in the Greater Everglades.

Sabine Grunwald, Soil & Water Science Dept, Univ of Florida, 2169 McCarty Hall, PO Box 110290, Gainesville, FL 32611, Todd Z. Osborne, Univ of Florida, IFAS, Soil and Water Science Dept, 106 Newell Hall / Box 110510, Gainesville, FL 32611, and K. R. Reddy, Univ Of Florida-Soil & Water Science Dept, 2169 McCarty Hall, PO Box 110290, Gainesville, FL 32611-0510.

The Greater Everglades wetland ecosystem has been impacted by numerous anthropogenic activities and natural forcing functions including hydrologic modifications, landscape fragmentation (canals, roads), nutrient inputs, fire, and tropical storms. This has caused shifts in both the pedo- and the biodiversity. Thus, relationships among soil and environmental factors are complex, non-linear, and often combinations of factors cause pedo-biological response patterns to emerge. Our goal was to gain a better understanding of complex relationships among soil and vegetative properties in the Greater Everglades. Our specific objectives were: (i) to identify properties that explain the variability of soil physico-chemical characteristics, and (ii) quantify relationships between soil and vegetative properties. We used soil observations collected at 1,341 sites at the 0-10 cm depth by the Wetland Biogeochemistry Laboratory, Soil and Water Science Department, University of Florida (K.R. Reddy) and South Florida Water Management District (S. Newman) and a 2003 Landsat Enhanced Thematic Mapper remote sensing image. The spectral reflectance values and indices from this image served as proxies to represent vegetation patterns and the mixed periphyton-soil-water interface. Ordination techniques and tree-based modeling were performed to disaggregate and explain the variability within the ecosystem and to describe interrelationships among soil and vegetative properties. Ecological variation in the Everglades could be explained by: (i) anthropogenic-induced nutrient gradients and subsequent transformations (carbon, phosphorus, nitrogen-cycles); (ii) underlying limestone bedrock material; (iii) vegetation patterns consisting of Cladium jamaicense Crantz (sawgrass), Typha domingensis Pers (cattail) and others; and (iv) differential patterns caused by the slough/ridge topography and associated hydrologic patterns. Complex linkages among properties were identified and provide insights into a heterogeneous and sensitive ecosystem. Understanding these pedo-biological relationships and patterns is essential to guide future restoration activities in the Greater Everglades.

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