Moisture and soil texture effects on soil CO2 efflux components in southeastern mixed pine forests.

摘要

Monitoring soil CO2 efflux rates and identifying controlling factors, such as forest composition or soil texture, can help guide forest management and will likely gain relevance as atmospheric CO2 continues to increase. We examined soil CO2 efflux and potential controlling factors in managed mixed pine-oak forests in Fort Benning, southwestern Georgia, USA. Soil CO2 efflux was monitored periodically in 2 stands that differed in soil texture in 2001 and 2002, and in 6 additional stands in 2003. Four stands had clayey soil (19.16-32.4% clay content) and four had sandy soil (4.6-12% clay content). We also monitored controlling factors such as soil temperature, moisture, organic layer mass, A layer depth, fine root production, soil microbial biomass carbon, and stand variables (basal area). Soil moisture and CO2 efflux varied with soil texture differences among the stands. As expected, soil temperature had a strong influence on soil CO2 efflux. Soil moisture, organic layer mass, and A layer depth also were correlated with soil CO2 efflux during periods of water stress, but these relationships differed with soil texture. Forest management activities can alter components of soil CO2 efflux, including soil carbon pools, temperature, and moisture; understanding the underlying variation of these components and resultant CO2 efflux over soil types can help guide management toward desired forest carbon balance trends in southeastern mixed pine forests.