Ground layer carbon and nitrogen cycling and legume nitrogen inputs following fire in mixed pine forests
Sara D. Lajeunesse1,4, John J. Dilustro2,5,
Rebecca R. Sharitz1,2,3 and Beverly S. Collins2
1Department of Plant Biology, University of Georgia, Athens,
Georgia 30602 USA
2Savannah River Ecology Laboratory, P. O. Drawer E, Aiken, South
Carolina 29802 USA
3Author for correspondence (email: sharitz@srel.edu)
4 Current address: Everglades National Park, South Florida Ecosystem
Office, 950 N. Krome Avenue 3rd Floor, Homestead, Florida 33030 USA
5 Current address: Department of Biology, Chowan College, 200 Jones
Drive, Murfreesboro, North Carolina 27855 USA
Abstract
Many mixed pine forests in the southeastern United States undergo prescribed
burning to promote open pine savannas. In these systems, soil texture
can influence fire's effect on vegetation and nutrient cycling. Our objectives
were to examine fire and soil texture effects on carbon (C) and nitrogen
(N) pools in ground layer vegetation. We measured biomass and tissue nutrient
concentrations and estimated legume N inputs via N2 fixation
in frequently burned sandy and clayey sites that were in the first and
second seasons following a prescribed fire in 2002 (B02) or had been unburned
since 2000 (B00). Mean belowground biomass was significantly greater on
sandy than on clayey sites. Total aboveground mean biomass did not differ
significantly between B00 and B02 sites, but grasses had greater aboveground
biomass in clayey than in sandy sites. Carbon and N pools (measured in
grams per square meter) in grasses were greater in clayey than in sandy
sites, yet grasses had greater tissue concentrations of C (as a percentage)
in sandy sites. Legumes showed significant interaction effects between
soil texture and fire frequency for tissue C and N pools, above- and belowground
biomass, and acetylene reduction activities. Results suggest that soil
texture can influence fire effects on ground layer vegetation in southeastern
mixed pine forests.
Key Words: fire frequency • ground layer biomass • herbaceous legumes • mixed pine forests • nitrogen • soil texture
SREL
Reprint #2926
Lajeunesse, S. D., J. J. Dilustro, R. R. Sharitz, and B. S. Collins. 2006. Ground layer carbon and nitrogen cycling and legume nitrogen inputs following fire in mixed pine forests. Am. J. Bot. 2006 93: 84-93.
