Grazing regulates temperate grassland multidimensional stability facing extreme winter snowfall reductions by influencing below‐ground bud density

Abstract

Global climate changes increased the frequency of snowfall reduction events in the Northern Hemisphere, consequently suppressing plant productivity. Grazing, the most widespread use of grasslands, influences productivity in response to climatic extremes by shaping community structure. Since grazing could disrupt normal plant growth and reproduction, rest from grazing at various stages of the growing season may have different effects on above‐ and below‐ground community properties. However, how grazing or grazing rest at different stages of growing season affects grassland stability when facing extreme snowfall reduction remains unclear. We investigated the multidimensional stability (resistance, resilience, recovery and temporal stability) of above‐ground net primary productivity (ANPP) under a time‐dependent strategic‐rest grazing practice (rest in early, peak and late growing stage) experiment, during which a natural extreme snowfall reduction event occurred. We also assessed plant richness, dominance, asynchrony, key functional group stability and below‐ground bud density to explore the mechanisms underlying multidimensional stability. We found that extreme snowfall reduction significantly decreased grassland ANPP under all grazing practices. However, grazing with short‐term rest during the peak growing stage significantly enhanced ANPP, improved resistance and recovery from extreme snowfall reduction, and consequently greatly improved the temporal stability compared to continuous grazing. In contrast, the grazing rest during the early and late growing stages did not improve temporal stability of ANPP. Meanwhile, resilience was not affected by grazing practices. The benefits of peak rest primarily arise from allowing the formation of sufficient below‐ground buds before and after extreme events. Notably, changes in community properties (such as diversity or asynchrony) resulting from the rest were not correlated with resistance and recovery. Additionally, the increases in grass bud density from the peak rest indirectly contributed to temporal stability by enhancing the stability of perennial rhizome grass and preserving community composition. Synthesis. These findings underscore the essential role of plant below‐ground buds in sustaining stable grassland productivity in response to snowfall reduction and also suggest that grassland management strategies should account for the protection of plant asexual reproductive organs, which contributes to grassland sustainability in the face of future climate change.