Soil respiration is correlated with rainfall and soil moisture at multiple temporal scales in a seasonal wet tropical forest

Abstract Soil respiration is the second largest natural flux of Carbon (C) between terrestrial ecosystems and the atmosphere, with tropical forests amongst the largest contributors to such soil-derived C effluxes. With climate change expected to drive changes in both temperature and rainfall, our ability to predict responses of the C cycle in the future hinges upon an understanding of how these factors influence soil respiration. However, these relationships remain poorly characterised across the seasonal tropics, especially South Asia. Here, for two seasonal tropical sites in the Western Ghats of India, we characterised annual, seasonal and temporal variation in soil respiration and assessed its temperature and moisture sensitivity over six years. At both sites, soil respiration was positively correlated with temperature at the instantaneous scale, but showed no relationship with temperature at seasonal or annual scales. In contrast, soil respiration showed significant relationships with rainfall and soil moisture at all temporal scales. At the annual scale, soil respiration was negatively correlated with total annual rainfall. At the seasonal scale, wet season Rs was significantly lower than in the dry season. At the instantaneous scale, Rs showed a parabolic relationship with soil moisture, where soil respiration increased with soil moisture up to ∼21 cm 3 cm -3 and decreased beyond that point. Our results suggest that future changes in the Indian summer monsoon, especially the frequency and intensity of extreme rainfall events, are likely to significantly impact soil respiration rates in this seasonal tropical forest.