Soil development in phosphate-mined created wetlands of Florida, USA

Abstract

Soil characteristics of a wide variety of created wetlands were compared to those of native wetlands in phosphate-mined areas from central and north Florida, USA. Criteria selected for evaluation of soil samples from 184 sites included soil compaction, bulk density, organic matter (carbon) and nitrogen content, C∶N ratio, and available and total nutrient contents. Organic matter accumulation, one of the indicators of a functional wetland, increased across transects going from uplands toward the center of the wetlands, and with wetland age. The organic matter accumulation rate in the AO and A1 horizons was 320 g m2yr−1. Native wetlands had significantly greater organic matter accumulation, both in the litter and mineral soil surface. The C∶N ratio of the soil organic matter decreased with created wetland age and approached values commonly found in wetland soils (15–25). Bulk density decreased with increasing organic matter content in the created wetlands, and low bulk density soils appeared to support better vegetative growth. Based on the above-mentioned parameters, reclaimed wetlands are slowly developing into “typical” wetlands; the rate of development could possibly be increased by minimizing soil compaction, incorporation of organic matter, or by fertilization.