Prioritizing conservation targets in a rapidly urbanizing landscape

We used an optimization modeling framework to devise spatially explicit habitat acquisition and restoration strategies for 19 remnant-dependent butterflies in a rapidly urbanizing county in the Chicago area. We first identified the smallest sets of protected sites that would contain at least one population of each species, and two populations for species present in multiple sites. We then identified undeveloped properties contiguous with these sites whose acquisition would further enhance conditions for focal species. Next, we considered parcels in the surrounding landscape that could potentially be acquired and restored to provide additional habitat. Assuming that the conservation value of additional habitats would increase with their proximity to protected sites, we examined tradeoffs between distance to sites and the cost of acquisition and restoration. The tradeoff curves generated by the model represented choices among sets of reserves that varied widely with regard to cost and distance. Among the non-dominated solutions for a given total area budget, the best solutions depend on the decision makers preference for these two objectives. Sets along the frontier of these curves differed in total cost due to the variation in the number of wetlands per parcel, the number and cost of parcels that must be acquired to provide sufficient habitat, and restoration costs. Several parcels appeared in all solutions and should be prioritized for acquisition. Our general approach is readily adaptable to other locations and planning objectives, but the models would need to be modified to accommodate different target species and their habitat requirements.