Fire has been used extensively as a management tool for coastal marshes on the Atlantic and northern Gulf of Mexico coasts. Prescribed burning of tidal marshes can be used as a management tool to:
• Reduce hazardous fuel conditions
• Protect and promote sensitive habitat for rare or endangered species
• Improve habitat for wildlife populations
Prescribed burning of tidal marshes has been a management tool at BNWR and in the adjacent state-owned Fishing Bay Wildlife Management Area (FBWMA) since 1933, with prescribed burns occurring annually since 1970. BNWR and FBWMA currently burn ~ 4,500 hectares of marsh on an annual basis (Fig. 4).
photos by Jim Lynch
Despite the known wildlife benefits of prescribed burning, there is little information available as to how prescribed burning influences vertical marsh development and marsh vulnerability to sea-level rise. The vertical development of BNWR marshes in response to sea-level rise occurs primarily through the accumulation of plant organic matter (e.g., litter and roots). The emergent vegetation allows the marsh to self-adjust to prevailing water levels through either the accumulation of dead plant material on the marsh surface, or through plant roots contributing to subsurface soil expansion and maintenance of soil elevation. Although prescribed marsh burning may influence all three processes driving soil organic matter accumulation (i.e., root production, root decomposition, and aboveground litter inputs), it is not clear whether prescribed burns positively or negatively influence marsh elevation (Fig. 5). Furthermore, it is not known how the frequency of prescribed burning (annual vs. multi-year intervals) may influence the balance between reducing marsh fuel loads and maintaining surface elevation. Understanding the relationship between fire, organic matter accumulation, and marsh sustainability is important in recognizing the limits and consequences of fire as a management tool in these coastal wetlands.
|Fig. 5. Conceptual diagram depicting the potential influences of prescribed burning on marsh elevation change.|