Erosion Effects on Carbon Dioxide Concentration and Carbon Flux from an Ohio Alfisol

Abstract

Carbon dioxide concentrations in soil both reflect and influence soil biological activity and C flux to the atmosphere. We hypothesized that erosion affects CO 2 concentration and C flux from the soil surface because of its effects on soil temperature and water regimes. The soil air concentrations of CO 2 and corresponding temperature and water contents were monitored on slight (SLI), moderate (MOD), severe (SEV), and depositional (DEP) phases at 2‐wk intervals between May 1996 and June 1997. The ambient soil CO 2 concentration and CO 2 –C flux were determined using gas chromatograph analyses. Seasonal patterns in soil air CO 2 concentrations (ranging from a winter low of 0.56 mL L −1 to a summer high of 20.90 mL L −1 ) predominated over more subtle differences (20–80% variation) due to erosion phase effects. Significantly greater (by 12–37%) CO 2 concentrations for SEV and MOD phases over SLI and DEP were observed mainly during the summer. The effects of the erosion phase on soil CO 2 concentrations appeared to be indirect through its impacts primarily on soil temperature and, presumably, soil biological activity. Soil air CO 2 concentrations were significantly correlated with soil temperature ( R 2 = 0.61) and CO 2 –C ( R 2 = 0.65) flux from the soil surface but not with soil water content. Both linear and second‐order polynomial regression equations using soil temperature predicted soil CO 2 concentration.