Groundcover carbon and nitrogen cycling and legume nitrogen inputs in a frequently burned mixed pine forest

Southeastern pine forests are often managed with prescribed burning to promote a pine overstory. Soil texture may influence fires effect on vegetation and nutrient cycling. My objectives were 1) to examine the effects of fire frequency and soil texture on groundcover plant carbon (C) and nitrogen (N) cycling by measuring their biomass and C and N tissue concentrations, 2) to assess legume N2-fixation rates, and 3) to predict the long-term effects of different fire frequencies on groundcover N cycling. Grasses had significantly greater aboveground biomass and C (g/m2) and N (g/m2) in clayey than in sandy sites, but had significantly greater tissue C concentration (%) in sandy sites. Legumes showed significant interaction effects between soil texture and fire frequency for aboveground tissue C (g/m2) and N (g/m2), biomass, and N2-fixation activities. These findings suggest that soil texture can influence fire effects on ground layer biomass and nutrient cycling.