Effect of soil temperature and soil moisture on CO2 flux from eroded landscape positions on black soil in Northeast China

Abstract

The CO2 flux from soils is an important part of the global carbon (C) cycle, whose dependence on erosion is as yet largely unknown. We hypothesized that erosion affects CO2 flux from the soil surface because of its effects on soil temperature and soil moisture. The CO2 flux, soil temperature, and soil moisture were monitored on summit, shoulder-slope, back-slope, and toe-slope on a sloping corn field in the black soil zone in northeast China once a day for 47 days between August 3 and September 18. The average CO2 flux varied significantly with slope positions ranging from 2.5±0.29 (mean±standard deviation)μmolm−2s−1 at summit to 1.5±0.32μmolm−2s−1 at toe-slope in the initial 27 days, but no significant difference among slope positions was observed in the last 20 days. Soil moisture contributed largely to CO2 flux in the initial 27 days, and soil temperature became the most important factor affecting CO2 flux in the last 20 days. In our study, second-order and first order regressions were fit the best models to predict CO2 flux at various slope positions based, respectively, on soil moisture content and soil temperature, with respective R2 ranging from 0.532 to 0.661 and 0.234 to 0.448.