Tuesday, 18 November 2003: 2:30 PM
Fire in wetland habitats: A 4-year evaluation in Maryland
From 1998 to 2001, we conducted a fire evaluation study on Blackwater National Wildlife Refuge managed by U. S. Fish and Wildlife Service and Fishing Bay Wildlife Management Area managed by the Maryland Department of Natural Resources. We compared the vegetative response of 2 fire rotations and fire exclusion in 6 tidal wetland areas. The 6 areas were divided into 2 treatment sites (annual burns and 3-year burn) and 2 control sites (no burn). Historical information on fire histories was not available for our sites (N=24); therefore, we burned all treatment and controlsites in 1998 to make them comparable to one another. Each year, we sampled percent cover and average height at 720 plots and biomass and stem densities at 240 plots from 1998-2001. Prescribed burns were conducted on the annual burn areas from January-March 1998-2002. The 3-year treatment sites were burned once from January-March 2001. We found no significant difference for cover among the treatment and control sites. However, we found a difference among years; 2001 having the greatest cover and 2000 had the least cover. For vegetation height, we found no difference among the treatments, but we found a significant difference among the years; 1999 had significantly shorter average height than the other years. In 1999, a drought may have limited the height of the vegetation. We found significantly greater live biomass among treatment and control sites. There was also significantly greater live biomass in 1998 than the other years. For stem density, we found that the annual burn sites had significantly higher stem densities than the 3-year treatment or control sites. In addition, we found significantly greater stem densities in 1998 than the other years. We recommend that prescribed burns be conducted approximately every 1 to 2 years if managers want to increase live biomass and stem densities.