As most regions of the earth transition to altered climatic conditions, new methods are needed to identify the most likely refuges for biodiversity and to prioritize conservation actions. A variety of metrics and approaches have been proposed. Some are based on predicting future climates and rates of change (“climate velocity”). Others use only information on the current environment, finding areas where there are steep elevation gradients or topographic variation (“environmental diversity”) that help species to find climate refuges nearby. Faced with high stakes and a wide array of conservation targets, planners and land managers need new tools to deal with these new challenges.
In a new open-access paper published in Global Change Biology, led by Carlos Carroll and co-authored by U of A researchers Diana Stralberg, Scott Nielsen, and Andreas Hamann as part of the AdaptWestinitiative, we set out to compare a variety of velocity and diversity metrics for conservation planning under climate change across North America. Specifically, we evaluated similarities and differences among different methods across different spatial scales and elevation ranges. Not surprisingly, we found substantial variation among metrics. But somewhat remarkably given uncertainty around future climate change projections, there was more variation among environmental diversity metrics based on current environmental conditions than among climate velocity metrics based on alternative future climates. We also found that while all diversity and velocity metrics generally increase with elevation, so do the contrasts among them, due to interactions between climate and terrain (see figure below).
So what is a planner to do, given all these differences? We suggest that metrics be combined, with areas of greater variation down-weighted (all spatial data are being made available through AdaptWest). Alternatively, finer-scale diversity metrics can be substituted where available, and supplemented with data on key target species as needed. Climate velocity metrics are useful for identifying broad-scale “macro-refugia,” where more species may find a long-term refuge from climate change. Areas of high environmental diversity should correspond with greater potential for local “micro-refugia” that can serve as temporary havens for species under a climate in flux. Where they coincide, short- and long-term conservation potential can be achieved most efficiently. We found that neither type was well-represented by the current protected area system, suggesting that much conservation work is still needed in order to prepare and adapt where possible to climate change.
Citation: Carroll, C., Roberts, D.R., Michalak, J.L., Lawler, J.J., Nielsen, S.E., Stralberg, D., Hamann, A., McRae, B.H., Wang, T. 2017. Scale-dependent complementarity of climatic velocity and environmental diversity for identifying priority areas for conservation under climate change. Global Change Biology (early view).