We know from paleoecological records and contemporary species movements that many species shift their ranges to track suitable climatic conditions. But with the current rapid rates of warming and land-use change, are these suitable conditions within reach?
To answer this question, we conducted new research that mapped connectivity across a human-modified landscape in western North America. Using both current climate data sets and future projections, we mapped potential movement routes that link where climate conditions are in the present to where they will be in the future. In other words, we linked climate analogs. We did so using a new approach based on electrical circuit theory that utilizes Circuitscape with a novel moving-window algorithm.
Our approach accounted for two key factors in determining connectivity: landscape permeability due to human modification, and species’ dispersal capabilities. Incorporating climate projections substantially shifted and curtailed the roadmap for species movement compared to connectivity maps based solely on landscape permeability (as they traditionally are). Our climate-informed approach highlighted a smaller number of specific locations important for movement, whereas connectivity maps without climate projections depicted more movement options.
What does this mean? Excluding climate projections from connectivity models may give an overly optimistic view of species’ ability to successfully shift their ranges, and may undervalue specific connections. Furthermore, representing climate change in one fell swoop—from one past or present point to one future point—obscures pathways that are important when two successive timesteps are used. Basing conservation decisions on a single, extended timestep will likely miss important movement routes, particularly over shorter time periods and for dispersal-limited species. Our results suggest a broader need in conservation decision-making to consider climate change as a dynamic process that unfolds continuously.
Conservation decision-making is challenged by considerable uncertainty surrounding the rates, magnitudes, and ecological consequences of climate change. And yet, conservation planners are necessarily prioritizing areas for protection to facilitate movement. Although planners may choose to avoid models that include future climate projections due to their uncertainty, our results suggest that, in doing so, critical locations may be overlooked. Routes that track changing climatic conditions will likely differ from those that connect present-day landscapes. Prioritizing areas for enhanced connectivity in a climate-informed manner will therefore be critical for protecting biodiversity.
Littlefield, C. E., B. H. McRae, J. Michalak, J. J. Lawler, and C. Carroll. 2017. Connecting today’s climates to future analogs to facilitate species movement under climate change. Conservation Biology. DOI: 10.1111/cobi.12938.