CO2 Flux of Soil Respiration in Natural Recovering Karst Abandoned Farmland in Southwest China

To estimate carbon sequestration potential in the karst area, soil respiration in a natural recovering karst abandoned farmland in Shawan, Puding, Guizhou, southwest China was continuously and automatically monitored for more than two years. The results show that the CO2 flux of soil respiration (2.63 ± 1.89 μmol m−2 s−1) is higher in the karst area than in non-karst areas under similar conditions but that regional value (1.32 μmol m−2 s−1) is lower because of larger rock fragment coverage (~  50 %). At the same time, the temperature sensitivity of soil respiration (Q10) in this study area is significantly higher than that of non-karst areas under similar conditions. Soil respiration has an obvious temporal variation, which is reflected in a significant exponential relationship between soil respiration and soil temperature, but the relationship between soil respiration and soil moisture is very complex. Especially, soil respiration has an obvious spatial variation, which is likely affected by different diffusion or water–rock reaction processes.