Increased frequency of extreme climatic events weakens the community stability of natural grassland under directional climate changes by reducing resilience

Aim

Chronic directional climate changes in temperature and precipitation are predicted to increase the frequency of extreme climatic events (ECEs); however, their co-occurring effects on the temporal stability of community productivity (i.e. ANPP stability) are still unclear. Here, we evaluate whether the increased frequency of ECEs reduces ANPP stability, and how it modulates the effects of chronic directional climate factors on ANPP stability in natural grassland.

Location

Twenty-two sites in Asia and 14 sites in North America.

Time period

1980s–2010s.

Major taxa studied

Herbaceous plant.

Methods

We collected 36 long-term observational and consecutive ANPP data (at least 10 years) and resampled yearly ANPP via a consecutive resampling method of nested time windows for each field. We used linear mixed-effect models, partial regression analysis and structure equation models to explore the interactive effects of three climatic factors on ANPP stability and their associated intermediate processes of sensitivity, asymmetry, resistance and resilience.

Results

The increased frequency of ECEs was observed within the long-term rising temperature and elevating precipitation trend across sites in the past several decades. Elevating precipitation rather than rising temperature was the primary driver influencing ANPP stability. Elevating precipitation increased ANPP stability through increasing mean ANPP and decreasing the standard deviation (i.e. SD) of ANPP due to a decrease in sensitivity of ANPP to precipitation. The increased frequency of ECEs decreased ANPP stability mainly by increasing the SD of ANPP, and it reduced the positive effect of elevated precipitation on ANPP stability via a decrease in resilience.

Main conclusion

Our results demonstrated that recurrent and discrete ECEs had cumulatively negative effects on ANPP stability, and the decreased resilience was identified as the primary factor reducing the grassland community stability under long-term climate change. This highlighted the potential risks of increased frequency of ECEs for grassland ecosystem functions.