AUTHOR=Qian Ruyan , Hao Yanbin , Li Linfeng , Zheng Zhenzhen , Wen Fuqi , Cui Xiaoyong , Wang Yanfen , Zhao Tong , Tang Ziyang , Du Jianqing , Xue Kai 

TITLE=Joint control of seasonal timing and plant function types on drought responses of soil respiration in a semiarid grassland

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.974418

DOI=10.3389/fpls.2022.974418

ISSN=1664-462X

ABSTRACT=Globally, droughts are the most widespread climate factor impacting carbon (C) cycling. However, as the second-largest terrestrial C flux, how responses of soil respiration (Rs) to extreme droughts co-regulated by seasonal timing and PFT (plant functional type) is still not well understood. Here, a manipulative extreme-duration drought experiment (consecutive 30 days without rainfall) was designed to address the importance of drought timing (early-, mid- or late- growing season) for Rs and its components (heterotrophic respiration (Rh) and autotrophic respiration (Ra)) under three PFT treatments (two graminoids, two shrubs and their combination). The results suggested that regardless of PFT, the mid drought had the greatest negative effects while early-drought overall had little effects on Rh and its dominated Rs. However, PFT treatments had significant effects on Rh and Rs in response to the late-drought, which were PFT-dependence: reduction in shrubs and combination but not in graminoids. Path analysis suggested that decrease in Rs and Rh under droughts were through low soil water content induced reduction in MBC and GPP. These findings demonstrate that responses of Rs to droughts depend on seasonal timing and communities. Future droughts with different seasonal timing and induced shifts in plant structure would bring large uncertainty in predicting C dynamics under climate changes.