Monitoring changes in plant community composition and landscape structure as a result of prescribed burning at Big Oaks National Wildlife Refuge
A vegetation monitoring program was initiated at Big Oaks National Wildlife Refuge (Big Oaks NWR) to help understand the effects of fire management on critical wildlife habitat. The objectives of this study were to produce a baseline description of plant community structure and composition and to describe the landscape-level impacts of fire management within the refuge. These grassland communities are important for managing rare grassland wildlife species, especially Henslow's sparrows. Permanent plots were established in three managed grassland communities. Information on plant community species composition and structure was collected during 2000-2001. Andropogon viginiana and Solidago juncea were the dominant plant species in the permanent plots. Rhus copallinum and Liquidamber styraciflua were the dominant woody species. Changes in landscape structure were determined using aerial photographs and a geographic information system (GIS). Vegetation data layers were created for 1995 and 1998 with vegetation patches classified using the National Vegetation Classification System (NVCS). Field data was collected during 2000 and 2001 to validate the data layers. Changes in composition and structure of nine vegetation classes were compared between burned and unburned areas. Percent cover of grassland area increased while sparse woodland and shrubland decreased during the study period. The amount of total patches and total edge declined in the burn areas. Mean grassland patch size increased while the number of grassland patches and grassland edge decreased in the burn areas. Therefore, the grassland areas within the burn units were more homogeneous in 1998. The results of this study were related to Henslow's sparrow population estimates in the fire management units.