| Ecosystem development of a young (13 years old) five pond wetland ecosystem on a coal surface mine in southern Illinois was studied from 1985 to 1987. Measured parameters included morphometry, hydrodynamics, soil and water nutrients, vegetative biomass, plant community characteristics (diversity, similarity, and density), and the seed bank.; Water levels fluctuated seasonally, with areal loss as high as 77 percent. Fluctuations exposed large areas of mudflats for seedling germination, yet plant growth was retarded due to rapid drying of these areas. Biomass was reduced and vegetative species diversity was increased by this process.; No clear pattern of vegetative community development was evident on any pond, with the exception of Pond 1 during 1985, when cattails predominated. Lack of community organization can be attributed to widespread germination of annuals following the rapid natural drawdown.; Water pH was low (4-5). Most water nutrient concentrations were within reported ranges for wetlands, as were most soil nutrient concentrations. Soil calcium and aluminum were somewhat elevated. Soil organic matter (9 percent) was low with respect to natural wetlands, but high compared with mineral soils.; Seed bank samples were relatively dissimilar with extant vegetation on the ponds. This can be attributed to patterns of invasion and germination by annual species.; The wetland ecosystem followed some of the trends expected for developing ecosystems. Included were a high P/B ratio, an increase in organic matter through time, poorly developed community structure, and domination by annuals.; Current theories on the effects of disturbance and stability on community structure do not appear to apply to this area. It is difficult even to determine whether a disturbance is present on the wetlands. High species diversity and low biomass production are likely attributable to initial patchy conditions, a currently harsh environment, and a non-equilibrium status on the ponds. |
