The primary purposes for using fire are to enhance marsh vegetation to support waterfowl, and to manage invasive plant species. The study was conducted for two consecutive years in 2004 and 2005, investigating the effects of prescribed fire regimes on vegetation biomass in tidal brackish marsh areas of the Blackwater National Wildlife Refuge located on the eastern shore of Maryland, USA, that are under relatively similar environmental conditions. Four different burn regimes (i.e., annual burn, 3-5 year burn, 7-10 year burn, and no burn) were applied in the study. Above-and below-ground vegetation biomass samples as affected by the different burn regimes were harvested in each year for five plant species native to the marsh; Distichlis spicata, Spartina alterniflora, Schoenoplectus americanus, Spartina cynosuroides and Spartina patens. No significant difference was found either in total above-ground biomass or in above-ground biomass by species between burn regimes in 2004. However, more total above-ground biomass was produced in annual burn regime in 2005 than in the other burn regimes. There were no consistent effects of burning on vegetative biomass production by species, but it seemed D. spicata was somewhat benefited by prescribed burning for its biomass production. Moreover, the stem density for D. spicata under annual burn regime was significantly higher than that in the other burn regimes, showing some positive effects of burning on vegetation. The below-ground biomass was significantly greater in 2004 than in 2005, yet with no significant difference between burn regimes in either year. A longer-term monitoring is strongly recommended.Key words: below-ground biomass, marsh vegetation, prescribed fire, tidal brackish marsh, vegetation biomass INTRODUCTIONFire is a natural and important component of many ecosystems (Lynch 1941, Komarek 1974, Abrahamson 1984, Pyne 2003, Omi 2005. In ecosystems where fire occurs frequently plants have developed complex adaptations (Bond and Keeley 2005). Historically, fire has been used in wetland ecosystems to remove vegetation to facilitate seasonal hunting and trapping. In Gulf Coast marshes, fire was used to expose alligators (Alligator mississippiensis) by making their water holes more visible (O'Neil 1949). In East Coast marshes, fire was used to facilitate trapping by making muskrat (Ondatra zibethicus) lodges more visible to hunters (Lay 1945).Recently, prescribed fire has become an integral part of resource management in wetlands and is widely accepted as a technique to stimulate the growth of wetland vegetation (Kozlowski and Ahlgren 1974, Main and Barry 2002, Slocum et al. 2003, Bond and Keeley 2005. For example, prescribed fire can help maintain the required conditions for fire-adapted plants species, by promoting the flowering of herbaceous species and fruit production of some Ecol. Field Biol. 33(4): 351-361, 2010 woody species (Lynch 1941, Main andBarry 2002). Fire can improve nutritional quality of plants for both wild and domestic animals, reduce hazardou...