Thursday, 10 November 2005 - 9:15 AM
326-5

Biogeochemical Succession in Early Development of Calcareous Wetland Soils.

Kanika Sharma1, Patrick Inglett1, Ramesh Reddy1, Andrew Ogram1, and Michael Norland2. (1) University of Florida, Soil and Water Science Department, 106 Newell Hall, Gainesville, FL 32611, (2) South Florida Natural Resources Center, 40001 State Road 9336, Homestead, FL 33034

Understanding of short term biogeochemical processes and parameters are important to evaluate recovery in restoration studies. The Hole-in-the-Donut (HID) region of the Everglades National Park, Florida USA was used to monitor these processes in five areas that are in different stages of recovery. These areas had been mechanically scraped and cleared completely to the bed rock (in years 1989, 1997, 2000, 2001, and 2003) in an attempt to remove the invasive Schinus spp. (brazilian pepper). Restored sites showed negligible recolonization by Schinus sp. while allowing revegetation of native wetland plant species that changed noticeably across the age gradient. Early development of soils across the age gradient (1-15 years) showed increasing TC, TN, and LOI concentrations. In contrast, TP concentrations declined with increasing soil age. Coincident with organic matter accumulation, analysis of soil δ 15N signatures indicates that N accumulation processes (e.g., nitrogen fixation) occur during the early stages of development, but lessen in the 15-yr old site. Organic matter δ13C indicates a dominance of algal or C-3 plant origin in soils of recently cleared sites, while organic matter of older sites appears to include progressively more C-4 plant C. Functional responses of these changes were determined by monitoring the microbially driven processes (enzyme activities, CO2 respiration, and soil oxygen demand) with respect to the nutrient level changes. Soil β-glucosidase activity increased in the first few years and then declined with age of the soils. Alkaline phosphatase activity was inversely correlated to the P concentration in soils. Additionally, this study compares the restored sites to the natural reference site in an attempt to assess the success of restoration.

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