Changing climate and increasing aridity represent a substantial challenge for land managers. As climate change progresses, understanding the resilience of plant communities to drought, and identifying strategies to enhance resilience, will become increasingly important for sustaining ecosystem structure and function. However, both the tools available for assessing resilience, and the strategies for promoting resilience, may vary across climatic gradients, ecosystem types, and spatial scales. Here, I synthesize results from studies in diverse vegetation types to examine the resilience of plant communities to historical and future drought. A network of long-term forest management experiments provides a unique opportunity to assess how forest density impacts tree growth resilience. Tree mortality on forest monitoring plots illustrates how stand density alters the resilience of tree survival to drought extremes. In dryland ecosystems, regeneration of long-lived perennial plants is a growing challenge for resource managers. Studies characterizing the environmental controls over regeneration suggest that resilience of plant regeneration to fluctuating drought may be adversely impacted in coming decades. At the largest spatial domain and longest temporal scale, categorical resistance and resilience classifications are widely utilized in land management and planning for drylands, although the applicability of these frameworks under future conditions remains unclear.
Results/Conclusions
These studies indicate that forest thinning promotes resilience of tree growth to drought in forests that span a surprisingly broad range of climatic conditions. In addition, tree mortality was higher in dryland forest monitoring plots with higher stand density, suggesting that resilience of tree survival during droughts, both past and future, can be enhanced by maintaining stands at low density. In both dryland forests and non-forested ecosystems, woody plant regeneration is episodic and very sensitive to environmental fluctuations, particularly extremes in temperature and soil moisture. Long-term resilience of the dominant woody plants in these drylands in the context of increasing drought may be enhanced by both recognizing the important role of regeneration, and by working with natural variability to capitalize on opportunities during periods of favorable conditions. The long-term directional climatic changes anticipated in the 21st century will create conditions that are not well represented by the current resistance and resilience categories, underscoring the need to anticipate future conditions and maintain flexibility in how resistance and resilience is described and landscape to regional scales. Results from these diverse studies can provide insight into drivers of plant resilience to drought and the growing challenge of quantifying and maintaining that resilience in coming decades.