Changes in carbon inputs affect soil respiration and its temperature sensitivity in a broadleaved forest in central China

Abstract

Soil respiration, as an important process in global carbon cycle, is drastically stimulated by warming. Changing plant carbon inputs caused by intensified human disturbances and climate change can complexly influence soil respiration and its temperature sensitivity (Q10). Although a number of experiments have been established in the world to explore the effects of changing carbon inputs, it remains a challenge to predict the direction and magnitude of changes in soil respiration and Q10 due to high spatiotemporal variability of climatic zone and ecosystem. Therefore, we conducted a field manipulative experiment to examine the impact of litter removal and root exclusion on soil respiration and Q10 in a deciduous broad-leaved forest in transition zone between subtropical and warm temperate zone. The results showed that litter removal significantly reduced soil respiration, microbial biomass carbon, soil organic carbon, total nitrogen and soil moisture. In addition, litter removal altered soil microbial community composition, expressed in increase of Gram-positive / Gram-negative bacteria ratio and percentage of actinomycetes, and enhanced microbial physiological stress index. Root exclusion significantly increased Q10 by elevating soil C/N ratio, which supporting “C quality-temperature” hypothesis. The study indicates that root exclusion may accelerate soil respiration under warming. Our study provides insights to improve carbon cycling models and accurately predict the consequences of climate change.