Zabin, C.J., Jurgens, L.J., Bible, J.M., et al. (2022). Increasing the resilience of ecological restoration to extreme climatic events. Frontiers in Ecology and the Environment, 20(5), 310-318. https://doi.org/10.1002/fee.2471

Summary

Extreme Climatic Events (ECEs) are rare, high-impact events such as hurricanes, heat waves, and extended drought, and they are increasing in frequency and intensity across the Pacific. These extreme events are one of the most immediate threats caused by climate change, and can provide increased opportunities for invasive species to colonize and spread. Despite potentially severe consequences, however, ECEs are rarely considered in planning efforts for ecological restoration. The authors examined the impacts of ECEs on restoration projects and the degree to which they were resilient to ECEs, and they found overwhelmingly negative impacts on restoration efforts. Impacts varied across geographies, species, and within sites, highlighting the need for restoration practitioners to adopt a “portfolio approach” to increase resilience of projects to ECEs. By diversifying the sites, species, and genotypes used as well as the methods employed, managers can reduce the risk of an entire restoration project failing when an extreme event occurs.

Results

Hurricanes and severe storms were the most reported ECEs, impacting 76% of the projects examined via wind, floods, and/or waves. The severity of impacts varied substantially by project and ECEs were not uniform across the restoration site, across all restoration methods, or across species, life stages, or genotypes.  Types of impacts included mortality, community shifts, impacts to reproduction of target species, change in vegetation structure, and changes in species cover. ECEs had overwhelmingly negative impacts on restoration projects, however a few reported both positive and negative impacts or neutral/no-damage impacts. One study reported a positive impact.

Management Considerations

• Plan for ECEs by considering the potential impacts of extreme events most likely to impact your area, possibly exceeding historical events.
• To spread risk through the “portfolio approach”, consider having multiple restoration sites instead of one; place restoration sites across scales (e.g., across elevational or rainfall gradients, or across multiple years or seasons to increase the likelihood of favorable conditions), make use of topographic complexity, and use multiple species.  If possible, identify likely spatial and temporal refugia and incorporate these into project design to reduce the impacts of ECEs.
• Consider selecting a diversity of propagule sources to enhance genetic diversity and adaptive potential to climate change. For example, incorporate species with traits that are more tolerant of extreme conditions such as droughts, heatwaves, or high winds.
• Consider having a post-ECE response plan in place that includes a budget for monitoring and invasive species control. Data on impacts from ECEs can help inform future restoration designs and guide adaptive management.

Take Home Points

• ECEs can create major setbacks for restoration projects by destroying or damaging structures or sites, and by threatening restored species.
• To increase the resilience of restoration projects to ECEs, spread risk across time and space by using the portfolio approach.
• Adapting restoration projects to ECEs or post-ECE recovery may require the use of propagules whose genotypes are more tolerant or resistant to ECEs.
• To adapt to climate change, including to an increasing frequency and severity of ECEs, restoration projects will need to plan for greater uncertainty, secure increased funding for monitoring and adaptive management in response to ECEs, and anticipate setbacks and longer timeframes for success.