Impacts of agricultural to urban land-use change on floristic quality assessment indicators in Northeastern Illinois wetlands

Northeastern Illinois is under heavy urban sprawl pressure leading to changes in land-use and negative impacts on existing wetlands directly adjacent to these new developments. Determining the impact of land-use changes on wetlands is important as it can have management and preservation implications within this region. One tool to evaluate these changes is the Floristic Quality Assessment (FQA), a method based on plant species composition at a site and the individual species habitat affinity and disturbance tolerance. The objectives of this study were to: 1) determine how wetland size, impervious surface, and distance from development influence FQA indicators and 2) determine if period (before/after development) and buffer size affect FQA indicators. Fourteen wetlands located in Northeastern Illinois were surveyed during 2004 through 2006 (prior development) and revisited in 2008 (post development). Positive correlations between wetland size and FQA indicators and between impervious surface and percent native species were found. In addition, species richness increased after development occurred and wetlands with larger buffers had higher percentages of native species. This study has demonstrated that larger wetlands are more diverse and land-use changes may not decrease wetland plant diversity in the short term in an urban setting.