Should public agencies and NGOs active in conservation focus on protecting habitats that are at imminent risk of being converted but are expensive or more remote areas that are less immediately threatened but where a large amount of land can be set aside? Variants of this trade-off commonly arise in debates over where best to locate protected areas. I examined this trade-off using a modified von Thunen model of land use change near a deforestation frontier. In formulating the conservation planners' problem, I used an ecological and economic discount rate to account for how decisions taken today account for ecological benefits and economic costs of conservation actions that would occur sometime in the future. As well as paying particular attention to the role of discounting in shaping recommendations about where to protect, I also considered the role of ecological heterogeneity, the rate of technological improvement as reflected in transportation costs and how important economic considerations are in shaping private landowners' decision-making.
Results/Conclusions
The land use change model predicts a wave-like spread of deforestation through time. When looking to set aside protected areas, the cost per hectare declines with distance. However, the probability of forest conversion also declines with distance. This captures the basic trade-off motivating the analysis. Whether investing near the present deforestation frontier or in more remote areas is optimal depends on what is assumed about how ecological benefits and economic costs accrue through time. A large economic discount rate favors protecting more remote areas, whereas a large, positive ecological discount rate favors protecting habitat near the current deforestation frontier. These effects of discounting continue to shape the results when accounting for spatial gradients in ecological quality, nonlinear effects of protected area size on species persistence or localized hotspots of peak ecological quality. In terms of other factors that we considered: protecting more remote locations is favored by increasing the rate of technological innovation or decreasing the importance of economic profit in influencing landowners’ decisions. How benefits and costs through time are accounted for warrants careful consideration when specifying conservation objectives and provides a niche axis along which conservation organizations may differentiate themselves when competing for donor funding or other support.