Prescribed fire may increase productivity of some brackish marsh species. An understanding of the mechanisms behind this stimulatory effect is important for land managers to maximize the benefits to the ecosystem. I found that canopy removal is the dominant mechanism through which fire stimulates biomass production in the marshes at the Blackwater National Wildlife Refuge in Dorchester County, Maryland. The stimulatory effect of canopy removal was stronger in sedge-dominated systems than grass-dominated systems. Faster sprouting sedge species may be able to take fuller advantage of light and soil temperature increases following canopy removal than later-sprouting grass species. Results of a greenhouse study indicated that canopy removal gives sedges a competitive advantage over grasses. These studies have numerous implications for land managers using anthropogenic disturbances as a management technique. Canopy-level disturbances, such as fire may increase productivity in sedge-dominated marshes and may suppress grass species in mixed compositions.