Increased interannual precipitation variability enhances the carbon sink in a semiarid grassland

1. The amplifying interannual precipitation variability has been observed globally and is projected to intensify under climate change scenarios. However, its impacts on terrestrial vegetation and carbon (C) sink have not been well investigated.

2. As part of a field manipulative experiment with three precipitation variabilities (20%, 40%, and 60%) in a semiarid grassland, this study was conducted to examine the responses of ecosystem C cycling to increased precipitation variability.

3. Across the 3 experimental years from 2010 to 2012, amplified precipitation variability enhances gross primary productivity (GPP) and ecosystem respiration (ER) as both GPP and ER were more sensitive to above- than below-average precipitation. In addition, the larger responses of GPP than ER to precipitation variability resulted in an enhancement of net ecosystem productivity (NEP), and the magnitudes of NEP increased with the increasing precipitation variability. More species with higher sensitivity...