A Preliminary Comparison of Meiobenthic Cladoceran Assemblages in Natural and Constructed Wetlands in Central Florida

In Florida, phosphate mining companies that destroy natural wetlands are required to construct mitigation wetlands. Comparisons of plant communities are frequently used to determine the degree to which constructed wetlands mimic natural wetlands, but efforts to address similarity based on fauna are rare. Studies in lake littoral zones suggest that meiobenthic cladocerans possess characteristics that may make their use in wetland comparisons advantageous. In this study, meiobenthic cladocerans were sampled from 8 natural freshwater wetlands and 11 freshwater wetlands constructed on phosphate-mined lands. The pulsed nature of the cladoceran communities limits their value as a quantitative measure of the similarity of natural and constructed wetlands. Qualitative analyses based on the presence or absence of species suggest that cladoceran assemblages of some constructed wetlands mimic those of some natural wetlands, but the range of assemblages found in constructed wetlands is narrower than that found in natural wetlands. © 1993 Society of Wetland Scientists

Ecological research in the Large-scale Biosphere-Atmosphere Experiment in Amazonia: Early results

The Large-scale Biosphere-Atmosphere Experiment in Amazonia (LBA) is a multinational, interdisciplinary research program led by Brazil. Ecological studies in LBA focus on how tropical forest conversion, regrowth, and selective logging influence carbon storage, nutrient dynamics, trace gas fluxes, and the prospect for sustainable land use in the Amazon region. Early results from ecological studies within LBA emphasize the variability within the vast Amazon region and the profound effects that land-use and land-cover changes are having on that landscape. The predominant land cover of the Amazon region is evergreen forest; nonetheless, LBA studies have observed strong seasonal patterns in gross primary production, ecosystem respiration, and net ecosystem exchange, as well as phenology and tree growth. The seasonal patterns vary spatially and interannually and evidence suggests that these patterns are driven not only by variations in weather but also by innate biological rhythms of the forest species. Rapid rates of deforestation have marked the forests of the Amazon region over the past three decades. Evidence from ground-based surveys and remote sensing show that substantial areas of forest are being degraded by logging activities and through the collapse of forest edges. Because forest edges and logged forests are susceptible to fire, positive feedback cycles of forest degradation may be initiated by land-use-change events. LBA studies indicate that cleared lands in the Amazon, once released from cultivation or pasture usage, regenerate biomass rapidly. However, the pace of biomass accumulation is dependent upon past land use and the depletion of nutrients by unsustainable land-management practices. The challenge for ongoing research within LBA is to integrate the recognition of diverse patterns and processes into general models for prediction of regional ecosystem function