Payment for ecosystem services for energy, biodiversity, conservation and poverty reduction in Costa Rica.

Interest in ecosystem services and the development of financial mechanisms to incentivize their protection have rapidly expanded over the past decade. The notion of ecosystem services and their value was described by (Daily 1997) with the publication of the book Nature's Services, which highlighted the notion that ecosystems provide human society with a variety of important needs. The valuation of these services was brought to light by (Costanza et al. 1997) who estimated that ecosystems provide humanity with 33trilliondollarsperyearinservices,whichwashigherthanglobalGrossNationalProduct,18 trillion dollars, when the analysis was conducted. The notion of ecosystem services was further popularized by the Millennium Ecosystem Assessment (MEA 2005) that identified four classes of services: provisioning, regulating, cultural, and supporting. In reality, the public and private interest in ecosystem services has surpassed our ecological knowledge regarding how ecosystems and biological communities interact to provide these services (Daily, personal communication). As ecosystem services continue to gain in popularity and in demand, it is critical that ecologists and economists continue to collaborate in understanding how to correctly value the provisioning of services, and how to ensure that the service purchased by the buyer is provided by the landowner.