Development of a Vegetation Map for Water Conservation Area 3

Ructhey, Ken; Love, Matt; Vilchek, Les

The environmental jewel ofthe Comprehensive Everglades Restoration Plan (CERPwww. evergladesplan.org), is the Water Conservation Area 3 (WCA-3) Decompartmentalization and Sheet Flow Enhancement (aka: DECOMP) project. Impoundments such as WCA-3, originally designed for flood control and water supply, must now be restored for their ecological value. A current vegetation map of this area was needed to establish baseline conditions. This mapping Project, initiated in 1994, is the first comprehensive detailed vegetation map produced for WCA-3. Water Conservation Area 3 is a 234, 913 ha impoundment located in the central portion of the remnant Everglades. In the late 19th century, human efforts began to control the timing, quantity, quality, flow, and distribution of water within this once vast pristine marshland. Impounding and partitioning activities were completed in phases starting in 1952 and ending in 1973, resulting in five sub-compartments that, over time, developed their own unique hydrologic and floral characteristics. More important than the effects of altered hydrology on plant community structure within these sub-compartments may be the changes in concentration and loadings of phosphorus (P) in waters flowing into this oligotrophic environment. These two attributes, altered hydrology and changes in concentration and loadings of P, have had significant effects on the original plant community structure and composition ofWCA-3. The objective of this mapping project was to create a seamless and complete GIS vegetation database ofWCA-3 utilizing 1:24000 scale color infrared aerial photographs to identify and code all vegetation communities using a single, hierarchal, classification system. Up to three codes of vegetation representing the dominant, co-dominant, and third dominant were included to label each polygon. Overall map classification accuracy was 89.7 percent. The total area mapped was 234,913 ha. comprised of 155,434 digitized and labeled polygons. The largest group of polygons (52,683 or 33.89%) was 0.01 to 0.05 ha in size. Sawgrass and Wet Prairie communities accounted for the greatest area (205,564 ha) and percentage (87 .5%) of polygons categorized for the entire project. This was also true for each of the five sub-compartments within WCA-3, where these two communities accounted for 76.16 94.68% of the labeled polygons. Cattail habitat encompassed five percent of the project area, or 11,751 ha. The relative contribution of cattail found in each of the sub-compartments ranged from 605 to 6861 ha. This final product provides the most detailed, spatially explicit vegetation information ever compiled for any part of the Everglades. It also provides the only current detailed vegetation map of WCA-3 and should provide a valuable baseline of information from which future mapping efforts for this area can be gauged. It is hoped that this mapping project provides a source of baseline information needed for the WCA-3 CERP Decompartmentalization project to succeed in restoring this environmental jewel of the Everglades.