Associate Professor of Biology Indiana University, United States
Abstract: Both droughts and very wet conditions are predicted to increase in frequency and severity in eastern North America. Despite these events acting in tandem to impact plant communities, responses to these events are generally evaluated independently; understanding community stability under these contrasting extremes requires an approach that captures the interplay between these events. This is particularly important as we might expect that community properties not only modulate community resistance and resilience to such events, but also shift in response to extreme events and consequently, impact future stability. To this end, we used two decades (2000-2020) of annual net primary productivity (ANPP) data from early successional grassland communities at Kellogg Biological Station LTER, Michigan, USA to evaluate the feedbacks between plant community properties and resistance and resilience to precipitation extremes.
The plant community properties that best predicted resistance and resilience differed between these two measures and between drought and wet events, and better predicted resistance than resilience (R2 = 0.17 and 0.09, respectively). Both forb and non-native species abundance, for example, were positively correlated with resistance to droughts, but showed the opposite relationship for wet events. Further, the focal community properties responded to precipitation events, often displaying non-linear responses. For example, dominant species (Solidago canadensis) abundance was positively correlated with both drought and wet event resistance, but decreased in response to wet conditions, suggesting that these resistance effects may be dampened under the oscillating precipitation extremes predicted for the future. Our results suggest that the same community properties that promote resilience also respond to extreme events, complicating predictions of the future stability of these systems.
