Landscape reclamation at a central Florida phosphate mine

Abstract

A 13-ha parcel of phosphate-mined land at the Gardinier Mine near Ft. Meade, Florida, USA, was reclaimed to test several design principles, establish planting and seed-dispersal trails, and monitor groundwater and surface water. The site was designed as a complete hydrologic unit with perched, basin, and lake-fringe wetland communities in upland communities. The design and placement of ecological communities resulted from the reclaimed topography and site hydrology. The percent growth for 11 wetland and mesic tree species averaged 127% (weighted average) in 3 years; some species averaged more than 160%. Percent survival ranged from 0% ( Cephalanthus occidentalis) to 100% for several mesic forest tree species ( Fraxinus pennsylvanica, Liquidambar styraciflua, Magnolia grandiflora). The percent survival of wetland species (weighted average) was 94.6%. An adjacent forested, floodplain wetland was evaluated as a source of windblown and bird-dispersed seeds to the site. Windblown seeds decreased in densities as distance from forest edge increased. Densities were from 125/m 2 to 380/m 2 within the forest, 50/m 2 to 120/m 2 at the forest edge and decreased exponentially as distance increased. Bird-dispersed seed densities at the base of constructed perches and tree “snags” ranged from 100/m 2 to more than 300/m 2. Rainfall and surface-water inflow along the edge of the site were the largest inputs to the reclaimed landscape's hydrologic budget. Groundwater flow and seepage were more important to growth and survival of planted species because of the maintenance of higher soil moisture during periods of drought.