Fewer Wetlands More Connectivity: Implications of Land use-Land cover Change in an Agricultural Landscape

St. Lucie County (SLC) is a 1,782 km2 area in east-central Florida that drains to the Nationally Significant Indian River Lagoon (IRL). It is low lying and nearly level, with widespread non-floodplain wetlands (NFWs) and few natural channels. NFWs comprise the vast majority of SLC wetlands, both in terms of numbers and area. Since the early 20th century, SLC has undergone extensive land use-land cover (LULC) change and is now characterized by citrus farming in the interior and municipalities on its eastern coast on the Atlantic Ocean. This LULC change has been made possible by the construction of an extensive drainage network, which has altered the way water is stored within and transmitted through this landscape. The net effect in this case has been to greatly reduce wetland area, significantly increase drainage density, and decrease the distances between individual wetlands and channels. Key aspects of these changes were measured, by mapping the spatial distribution of wetlands and natural and artificial channels (1850, and 2004) before and after the most intense period of LULC change, and by calculating spatial metrics to quantify change. The reduction in wetland area and the increase in drainage density have been pronounced, resulting in a pronounced decrease in the distances between individual wetlands and channels. These results show that wetland water storage in the county has been decreased, with water instead being routed more efficiently to coastal waters. The loss of wetlands and enhanced hydrologic connectivity in SLC have implications for the IRL, where chronic and acute water-quality degradation and related harmful algal blooms (HABs) have become the norm. The author recommends that local LULC change be given careful consideration, armed with the measurements and structured data developed for this analysis, in ongoing efforts to address these growing threats to the ecological integrity of the IRL and similar coastal water