Responses of soil respiration to rainfall depth and frequency in semiarid grassland communities

Abstract

Climate change is increasing the extreme precipitation depth and frequency, which may cause a strong response of ecological processes in drought regions. To investigate how rainfall depth and frequency alter soil respiration (SR), a rainfall simulation experiment was conducted in grassland communities dominated by Artemisia gmelinii and Lespedeza davurica in Loess Plateau of China. SR rate (Rs), soil temperature (Ts) and soil volumetric water content (Sv) were monitored before and after the rainfall treatments, that is, four depths (5, 10, 20 and 40 mm) and three frequencies (40 mm × 1, 20 mm × 2 and 10 mm × 4) during the growing season (June to September). Results indicated that the response magnitude of Rs increased with rainfall depths, reaching the maximum under 40 mm, and the increments were tightly related to rainfall frequency and community type. The increase and mean value of Rs in A. gmelinii community were significantly higher than those in L. davurica and bare land under same rainfall depth. L. davurica community was more sensitive to rainfall lower than 10 mm, whereas it had weaker but longer response under rainfall larger than 10 mm compared with A. gmelinii community. Successive rainfall events dampened the pulse effect of Rs but generated more cumulative CO2 emission in vegetation communities. Ts and Sv varied significantly with rainfall depth and co-regulated SR. These findings implied more CO2 will be released from soil in the semiarid grasslands under extreme and successive rainfalls and emphasized the importance of species impact on SR for soil carbon evaluation under future rainfall regimes. © 2021 John Wiley & Sons, Ltd.