Estimating the impacts of conservation on ecosystem services and poverty by integrating modeling and evaluation

Scholars have made great advances in modeling and mapping ecosystem services, and in assigning economic values to these services. This modeling and valuation scholarship is often disconnected from evidence about how actual conservation programs have affected ecosystem services, however. Without a stronger evidence base, decision makers find it difficult to use the insights from modeling and valuation to design effective policies and programs. To strengthen the evidence base, scholars have advanced our understanding of the causal pathways between conservation actions and environmental outcomes, but their studies measure impacts on imperfect proxies for ecosystem services (e.g., avoidance of deforestation). To be useful to decision makers, these impacts must be translated into changes in ecosystem services and values. To illustrate how this translation can be done, we estimated the impacts of protected areas in Brazil, Costa Rica, Indonesia, and Thailand on carbon storage in forests. We found that protected areas in these conservation hotspots have stored at least an additional 1,000 Mt of CO ₂ in forests and have delivered ecosystem services worth at least $5 billion. This aggregate impact masks important spatial heterogeneity, however. Moreover, the spatial variability of impacts on carbon storage is the not the same as the spatial variability of impacts on avoided deforestation. These findings lead us to describe a research program that extends our framework to study other ecosystem services, to uncover the mechanisms by which ecosystem protection benefits humans, and to tie cost-benefit analyses to conservation planning so that we can obtain the greatest return on scarce conservation funds. Significance Research shows how the potential services from ecosystem conservation can be modeled, mapped, and valued; however, this integrative research has not been systematically applied to estimate the actual impacts of programs on the delivery of ecosystem services. We bridge this divide by showing how protected areas in Brazil, Costa Rica, Indonesia, and Thailand store carbon and deliver ecosystem services worth at least $5 billion. Impacts on carbon are associated with poverty exacerbation in some settings and with poverty reduction in others. We describe an agenda to improve conservation planning by ( i ) studying impacts on other ecosystem services, ( ii ) uncovering the mechanisms through which conservation programs affect human welfare, and ( iii ) more c