Evaluation of soil CO2 efflux and its influence factors in a revegetated area in Tengger Desert, NW China

Abstract

Soil profile CO2 transport and production are vital in the carbon stock in desert artificial vegetation ecosystem. In this study, the soil profile CO2 concentration, soil water content and temperature at depths of 0-40 cm were measured at four revegetated sites (1956, 1964, 1981 and 1987), located in the southeastern edge of Tengger desert, China. The gradient method was applied to simulated soil gas diffusion coefficient and soil profile CO2 efflux. We found that the soil profile CO2 concentration increased with depths, while the soil CO2 diffusion coefficient, soil CO2 efflux and production in upper layers were significantly higher than those in bottom layers. The CO2 diffusion coefficient decreased at first and then increased with revegetation age. The soil profile CO2 concentration, CO2 efflux and production increased with revegetation age. The simulated soil surface CO2 efflux were 0.54 μmol•m −2 •s −1 , 0.49 μmol•m −2 •s −1 , 0.44 μmol•m −2 •s −1 and 0.25 μmol•m −2 •s −1 at 1956, 1964, 1981 and 1987 revegetated sites, respectively. The soil surface CO2 efflux mainly came from the layers of 0-10 cm, which contributed to 76.4% -94.9% of the total. The structural equation modeling (SEM) explained 97.0% of the variations in soil surface CO2 efflux (F0). The effects of soil CO2 concentration, temperature and water content in the layers of 10 cm, and plant properties on soil surface CO2 efflux were 0.977, 0.516, -0.358 and -0.156, respectively, and the interaction between soil temperature and water content was 0.439, which meant that the soil temperature and water content significantly influenced soil CO2 efflux.