Effect of manipulated precipitation during the growing season on soil respiration in the desert-grasslands in Inner Mongolia, China

The dynamics of soil respiration are crucial in understanding carbon cycling and its feedback to climate change. However, little information exists regarding the response of soil respiration to precipitation variation. To examine the response of soil respiration to precipitation variation through biogeochemical regulation, a manipulative field experiment was conducted along a precipitation gradient (-60%, -40%, -20%, CK = natural precipitation, + 20%, +40% and +60%) in a native desert grassland ecosystem in Inner Mongolia. Plant biomass, total soil carbon and soil respiration were determined across the precipitation treatments during the growing season (from late May to early October) in 2017. Above-ground biomass tended to increase but total soil carbon varied little with an increase in precipitation. Soil respiration exhibited a unimodal curve diurnally in all precipitation treatments, peaking between 09:00 and 13:00, but showed irregular patterns seasonally. Both the daily and seasonal average soil respirations increased with an increase in precipitation (diurnal Rs ranged from 0.37 mu mol m(-2)S(-1 )to 0.75 mu mol m(-2)S(-1); seasonal Rs ranged from 0.43 mu mol m(-2)S(-1) to 0.66 mu mol m(-2)S(-1)). Soil respiration was correlated positively with precipitation-induced change in above-ground plant biomass, but was correlated negatively with precipitation-induced change in total soil carbon. It was concluded that carbon released from the soil increases with an increase in precipitation.