Precipitation Variability Has a Weak but Significant Stabilizing Effect on Community Structure

Climate variability is an important factor leading to spatial and temporal changes in structure and functions of plant communities. Exploring the temporal stability of communities in response to climate variability is essential for further evaluating the impacts of climate change to ecosystem functions and services. Current research on climate variability mainly focuses on plot-scale experiments (alpha scale), while how it impacts the long-term stability of a metacommunity (gamma scale) still needs further study. We analyzed the effects of climate variability on the temporal stability of plant communities at alpha and gamma scales based on a long-term observation of plant cover from 1938 to 1968 in a mixed-grass prairie in Kansas, western United States. The results demonstrated that precipitation variability strengthened alpha and gamma stability of plant cover, while the temporal mean of temperature has opposite effects on them. Precipitation variability enhanced alpha stability directly and indirectly by increasing species asynchrony, though its positive effects were weak. Alpha stability combined with spatial asynchrony further promoted gamma stability. We therefore concluded that precipitation variability had a weak but significant stabilizing effect on community structure. These findings reveal the role of precipitation variability in temporal stability of community structure at alpha and gamma scales over decades, which could contribute to a more comprehensive understanding of the conservation of biodiversity and ecosystem functioning under the future climate change. Our study emphasized that both temporal mean and standard variation of climate should be considered when exploring the effects of climate change on ecosystem functions.