Drought and heat wave impacts on grassland carbon cycling across hierarchical levels. (19th April 2020)

• Record Type: Journal Article
• Authors: Li, Linfeng; Zheng, Zhenzhen; Biederman, Joel A.; Qian, Ruyan; Ran, Qinwei; Zhang, Biao; Xu, Cong; Wang, Fang; Zhou, Shutong; Che, Rongxiao; Dong, Junfu; Xu, Zhihong; Cui, Xiaoyong; Hao, Yanbin; Wang, Yanfen
• Is Part Of: Plant, cell and environment. Volume 44:Number 7(2021)
• Page Start: 2402
• Page End: 2413
• Publication Date: 2020-04-19
• Subjects: biomass -- climate extremes -- CO2 flux -- compensatory effect -- global change -- Inner Mongolia -- leaf physiology -- precipitation; Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.13767
• Languages: English
• ISSNs: 0140-7791

Abstract

Abstract: Droughts and heat waves are increasing in magnitude and frequency, altering the carbon cycle. However, understanding of the underlying response mechanisms remains poor, especially for the combination (hot drought). We conducted a 4‐year field experiment to examine both individual and interactive effects of drought and heat wave on carbon cycling of a semiarid grassland across individual, functional group, community and ecosystem levels. Drought did not change below‐ground biomass (BGB) or above‐ground biomass (AGB) due to compensation effects between grass and non‐grass functional groups. However, consistently decreased BGB under heat waves limited such compensation effects, resulting in reduced AGB. Ecosystem CO2 fluxes were suppressed by droughts, attributed to stomatal closure‐induced reductions in leaf photosynthesis and decreased AGB of grasses, while CO2 fluxes were little affected by heat waves. Overall the hot drought produced the lowest leaf photosynthesis, AGB and ecosystem CO2 fluxes although the interactions between heat wave and drought were usually not significant. Our results highlight that the functional group compensatory effects that maintain community‐level AGB rely on feedback of root system responses, and that plant adjustments at the individual level, together with shifts in composition at the functional group level, co‐regulate ecosystem carbon sink strength under climate extremes. Abstract : It is indispensable to explore the mechanisms and impacts of climate extremes on the carbon cycle given they are increasing in magnitude and frequency. Aboveground biomass responses to climate extremes rely on the functional group compensatory effects and feedbacks of root system responses. Plant physiological adjustments and shifts in community composition co‐regulate ecosystem CO2 fluxes under climate extremes.