Decoupled responses of above- and belowground productivity stability to drought and clipping in an alpine meadow

Abstract

Extreme drought and land-use intensification pose significant threats to ecosystem stability. However, existing studies that assess ecosystem stability primarily focus on above-ground net primary productivity (ANPP) stability and overlook the importance of below-ground net primary productivity (BNPP) stability. Here, by manipulating five levels of precipitation treatment (1/12 P, 1/4P, 1/2P, 3/4P, and P) and clipping (unclipped vs. clipped) over 7 years (2016-2022) in an alpine meadow, we examined the response patterns and drivers of ANPP stability and BNPP stability to drought and clipping. The results showed that extreme drought decreased ANPP stability but moderate drought increased BNPP stability, which challenges the traditional view that extreme drought could destabilize ecosystem stability based solely on results from aboveground processes. Besides, clipping had no impacts on ANPP stability but reduced BNPP stability, and clipping differentially regulated the stability of above- and below-ground productivity in response to extreme drought in our study.  Furthermore, ANPP stability was primarily driven by species asynchrony rather than species richness, whereas dominant species stability contributed strongly to the variations in BNPP stability of this alpine meadow confronted with drought and clipping. This study provides compelling experimental evidence for the decoupling in responses of ANPP stability and BNPP stability to extreme drought and clipping. Our findings indicate that aboveground responses should not be a sole predictor of the whole ecosystem-scale consequences of extreme drought and clipping on ecological stability, and lay stress on the necessity of evaluating ecosystem stability from a whole ecosystem perspective.