Cooperative Fish and Wildlife Research Units Program: all
Education, Research and Technical Assistance for Managing Our Natural Resources

The challenges of selecting strategies to adapt to climate change and other anthropogenic impacts is further complicated by the presence of irreducible uncertainties regarding future conditions. Decisions on long-term investments in land protection to achieve conservation objectives contain significant risk of failure due to these uncertainties. To address this challenge, decision makers need an arsenal of sophisticated but practical tools to help guide spatial conservation strategies. Theory asserts that managing investment risks can be achieved by diversifying an investment portfolio to include assets that are neutral or negatively correlated under a given set of conditions. We demonstrate an approach for formalizing the diversification of conservation assets (land parcels) by using their correlation structure to quantify the degree of risk for any proposed reserve design. We then apply this metric to identify optimal spatial investment portfolios by appropriately balancing risk with the expected conservation benefit. We illustrate a framework for identifying potential future habitat refugia to manage an endangered amphibian by integrating species distribution modeling, scenarios of climate change and sea level rise, and impacts to critical habitat. Using the plains coqui (“coqui llanero”), known from only three small wetland populations on Puerto Rico’s coastal plains, we evaluate the distribution of refugia for eight future scenarios and apply portfolio theory to help guide investment strategies to mitigate climate risks and increase the persistence of this species in the face of an uncertain future. Modeling projects substantial loss of Puerto Rican wetlands and reductions in species distribution, but conditional on the future scenario and with losses not equally distributed across the northern coast. Currently protected areas in the north, while offering limited protection of current llanero distribution, may contribute considerable value to future refugia. Optimizing a protected-area design with the objective of managing risk provides insights on possible benefits and limitations relative to an alternate strategy focused on maximization of cumulative conservation benefits. Some apparent limitations in outcomes of the risk-benefit optimization may be due to the availability of only a small percentage of negatively correlated parcels with which to reduce risk.