Nutrient Levels and Organic Matter Decomposition in Response to Prescribed Burns in Mid-Atlantic Coastal Marshes

Abstract

Prescribed winter burning is a commonly used management practice in coastal marshes along the Atlantic Coast. I conducted a manipulative field study to explore the mechanisms by which fire increases plant productivity. I found that prescribed fire does not provide a fertilization effect for vegetation through ash deposition due to the low amounts of nutrients in ash. Modeling biomass nutrient stocks in other marshes with similar vegetation types shows that this lack of a fertilization effect likely exists across all coastal marsh types. Through the mechanism of canopy removal, organic matter decomposition rates in marsh areas tended to decrease later in the growing season, corresponding with a decrease in porewater ammonium and phosphate, which were taken up in much higher quantities in the biomass. These effects were stronger and more consistent in areas dominated by the sedge species, as these areas showed more of a biomass response to canopy removal.