Responses of soil respiration to spring drought and precipitation pulse in a temperate oak forest

摘要

As- a consequence of climate change, a higher frequency of spring drought periods followed by episodic precipitation events is predicted for Central China. Little is known about the effect of drought intensity on the response of soil CO2 efflux to discrete precipitation events in forest ecosystems. A field experiment was conducted to assess the responses of soil CO2 efflux to spring drought and precipitation pulse in an oak forest located at climatic transitional zone in Central China. Soil respiration (SR) and heterotrophic respiration (HR) under 30-day drought showed higher responses to precipitation pulse than those under control and 20-day drought treatments. Regardless of drought intensity, precipitation events of 5, 10, and 20 mm levels significantly increased SR by 86.0, 103.4, and 175.2%, and HR by 108.4, 129.5, and 161.5% when compared with non-water addition plots, respectively. Severe drought treatment (30-day drought) amplified the contribution of HR to SR in response to precipitation pulse (84.5% vs 78.3% for the control). Drought intensity rather than precipitation amount showed substantial influence on total carbon loss through SR and HR. These findings highlight the importance of incorporating both drought intensity and precipitation events and their impacts on soil carbon cycling into future predictions of forest ecosystems under climate change.