Climate change adaptation strategies are human responses to a climate change impact that have been designed to reduce harm, or take advantage of new opportunities, as the climate continues to change. Here we use “ecological drought adaptation strategies” to mean responses that specifically address drought impacts on ecological systems. Note that climate change adaptation strategies differ in intent from climate change mitigation strategies, which focus on reducing the drivers of climate change, and include efforts to reduce the use of fossil fuels that contribute carbon dioxide to the atmosphere. Ecological drought adaptation strategies will likely include actions and tools that are also incorporated into drought preparedness, drought response, and drought mitigation strategies. Tools and actions from drought planning are highly relevant - but we frame responses as climate change adaptation to highlight the role of climate change as an increasingly important factor shaping patterns of drought occurrence, drought intensity, and the potential for ecological transformations (e.g., a change from forest to grassland) following major climate-intensified drought events. Similarly, while not explicitly in the title, consideration of the role that human water use plays in reducing water availability for nature is an important aspect of “adapting” to drought risks under climate change. As described in our Ecological Drought Framework, strategies here emphasize reducing ecological risks, which we expect will benefit people by helping to maintain key ecological services. We expect this broadening of the scope of drought planning to address connections between ecological vulnerabilities and human well-being and water use, as well as climate change, will require updates to drought planning approaches. ecoDIVA is intended to help support groups in the process of making these updates, so communities can be better prepared for current droughts, and droughts of the future.

To be as effective as possible, an ecological drought strategy should directly address the most important drought driver(s). We expect that in many places, long term investment in managing ecological resources in appropriate ways, on appropriate sites, will reduce the risks of drought impacts to people and nature. However, we also expect increases in the severity of drought (higher probability of “megadroughts,” as well as more episodes of drought that exceed the adaptive capacity of the current system), where early warning of impacts may be the best we can hope for in terms of strategic response. While these ideas can be hard to accept, the need to think about thresholds is an important insight, as we are likely better off not investing limited resources in on-the-ground actions that are not likely to be successful. The key challenges are how do we evaluate the risks to the systems and services we care about, and evaluate the potential costs and benefits of action?

ecoDIVA presents maps and other visualization tools that describe watershed-specific relationships between tree health responses and a suite of drought drivers; variables with the largest “petal” are most strongly linked to the tree health response. Recall that these patterns were observed during a specific drought period, do not reflect all possible drought drivers, and often vary across watersheds - so they should be interpreted with these caveats in mind. For those tasked with conservation planning, management, or restoration of these forests, and for stakeholders interested in sustaining forest-based ecosystem services, a next step might be to identify adaptation strategies that can be deployed in response to the specific drought driver(s) that are most closely related to the tree health decline in a focal watershed. In the set of strategies below, drivers and responses are grouped according to our Ecological Drought Framework. We hope that connecting spatial data and strategies in this way helps groups of collaborators build a shared understanding of what is at risk, and how they can most effectively invest resources for management and restoration.

The ecological drought adaptation strategy list below is in development, and is primarily intended to illustrate the linkage between key drivers identified in the model and relevant actions; it is not exhaustive or prescriptive. Components of actions often overlap across the topical areas, reflecting the inherent connectedness of all of the factors influencing drought exposure, sensitivity, adaptive capacity, and impacts on people and nature. Similarly, a final management plan might incorporate concepts from multiple strategy types, reflecting the interaction between multiple drivers, and the idea that risks can often be reduced through the application of several management tools or siting decisions. Most notably, constraints related to identifying appropriate data for human water use in this example carries through to our presentation of responses - we lack adaptation examples for these forested watersheds that focus on ways to reduce impacts from human water use. In future case studies, we will expand our modeling breadth to include aspects of human water use that act as drivers of drought risk.