Effects of continuous drought stress on soil respiration in a tropical rainforest in southwest China

Abstract

Drought is predicted to have a profound impact on soil respiration. This study aimed to assess the effects of long-term precipitation decrease on soil respiration in a tropical rainforest. A precipitation reduction experiment was conducted in a tropical forest in southwest China at the beginning of 2011. Soil respiration and environmental parameters were measured monthly for three years. The continuous precipitation reduction treatment did not affect the seasonal patterns of soil respiration, but it significantly increased soil respiration in the study plot during the rainy season, and the relationship between soil respiration and soil moisture differed in the control and reduction treatment in the rainy season. Compared with the net ecosystem exchange of carbon in this system, the increment of annual soil carbon emissions in the reduction treatment was considerable and should not be ignored. Our results indicate that the responses of soil respiration to precipitation decrease may vary seasonally and the variation of volumetric water content in different seasons may be an important factor leading to the seasonal variation. The variation of soil moisture among different ecosystems as well as in different seasons should be taken into consideration when predicting the future response of soil respiration to drought globally.