Trade-offs Between the Value of Ecosystem Services and Connectivity Among Protected Areas in the Upper Chattahoochee Watershed

The Upper Chattahoochee Watershed supplies most of the drinking water to the Atlanta Metropolitan Area, a region with one of the fastest urban growth rates in the United States. Smart conservation planning is necessary to conciliate urban development and the provision of critical ecosystem services (ESs) such as water quality, carbon storage, and wildlife habitat. We employed optimization models to compare the value of the ESs provided by alternative allocations of land parcels for conservation. We adopted boundary penalties to determine the trade-offs of choosing higher connectivity among parcels regarding economic values provided by carbon storage, wildlife habitat, and water quality. We used InVEST models to quantify and map ESs and value transfer to assign economic values to them. We set low and high ESs economic value bounds and discounted their values to perpetuity using 3% and 7% discount rates. Our results indicate that incorporating boundary penalties results in solutions with larger, fewer, and more connected parcels but yields lower economic benefits than unconstrained models. However, these differences are relatively small (between 2.6% and 7.3% loss in economic value). Additional transaction costs of purchasing more parcels and improving ecological networks provided by larger forest patches might justify the selection of solutions with higher connectivity. Decision-makers can use the developed models for estimating the economic cost of selecting connected parcels for conservation purposes at the landscape level.

Automated summary

The Upper Chattahoochee Watershed provides drinking water for the rapidly growing Atlanta Metropolitan Area. This study examines the trade-offs between urban development and ecosystem services by comparing the economic values of different land conservation strategies. The results show that while solutions with higher connectivity yield lower economic benefits, the differences are relatively small. The additional costs of purchasing more land and improving ecological networks may justify selecting solutions with higher connectivity.