Enhanced Ecological Succession Following Phosphate Mining

摘要

The research addressed four components thought to be essential for enhancing establishment of native forested ecosystems on phosphate surface-mined lands. Those components were: multispecies mixture of seeds, mycorrhizal fungi symbionts, soil nutrients, and organic matter. Studies of plant community succession and mycorrhizal colonization revealed that within three years the majority of invading plants had levels of mycorrhizal infection higher than the level in mature ecosystems. Mycorrhizal inoculation greatly enhanced the growth of sweat gum (Liquidambor styraciflun), and a composite of mycorrhizal species from phosphate lands was more effective than Glomus macrocarpum, a common Florida nature mycorrhizal fungus. Soil seed banks in reclaimed wetlands approached the density and diversity of seed banks in natural marshes in about five years, although the actual vegetation present was not always as diverse, dense, or well developed in the reclaimed marshes unless wetland soil had been applied. An effective method for mechanically planting several species of seeds plus mycorrhizal inoculum was the use of several row planters attached to a tractor mounted tool bar. During the initial growing season, mulch, topsoil and endomycorrhizal inoculum enhanced growth, density, and species richness of tree seedlings, while ectomycorrhizal inoculum had almost no effect, and gypsum application and phosphate-free fertilizer had negative effects.