Spatial Distribution of Soil Nutrients in a Northern Everglades Marsh: Water Conservation Area 1
- S. Newman ,
- K. R. Reddy,
- W. F. DeBusk,
- Y. Wang,
- M. M. Fisher and
- G. Shih
Everglades Systems Research Division, South Florida Water Management District, P.O. Box 24680, West Palm Beach, FL 33416-4680
Univ. of Florida, Inst. of Food and Agricultural Sciences, Soil and Water Science Dep., 106 Newell Hall, Gainesville, FL 32611
Water Resources Evaluation Dep., South Florida Water Management District, P.O. Box 24680, West Palm Beach, FL 33416-4680
The Florida Everglades developed as a nutrient-poor, rain-fed ecosystem. However, for the past 30 yr, the Everglades have received nutrient-enriched surface water runoff from the adjacent Everglades Agricultural Area (EAA). This study examines the response of a pristine wetland, Water Conservation Area 1 (WCA 1), part of the northern Florida Everglades, to nutrient loading as documented by soil nutrient concentrations. During 1979 to 1988, WCA 1 received 138 t total P (TP) and 4919 t total N (TN), retaining 53% of the TP load and 58% of the TN load. Analyses of the spatial distribution of soil N and P showed steep gradients of TP along the western canal boundary, adjacent to inflow points importing EAA runoff. Surficial soils (0–10 cm depth) at interior marsh sites had a mean TP concentration of 368 mg kg−1, compared with 1028 mg kg−1 measured at sites adjacent to the western canal. Similar trends were observed for soil Ca and Mg, while C and N did not show the same boundary effects on spatial enrichment. Nutrient-enriched sites also had higher porewater soluble reactive P (SRP; 0.15 mg L−1) and NH4-N (1.65 mg L−1) than unenriched sites (SRP = 0.02 mg L−1, NH4-N = 0.85 mg L−1). Of the 90 sites sampled, 66 sites consisted of sloughs and sawgrass (Cladium jamaicense Crantz); the remaining 24 sites were either cattail (Typha spp.) dominated or had a significant cattail presence. These 24 cattail sites were closest to the nutrient inflow areas and had the highest soil nutrient concentrations.
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