An ecosystem services framework to sustain biodiversity in a watershed in conflict: Supply of consumer-provided services
Effective biodiversity conservation must involve the human systems in which organisms and ecosystems are embedded. Ecosystem services valuation has become a popular approach to weighing tradeoffs in environmental management, particularly where natural resources such as freshwater are limited. A key challenge in valuation is developing a comprehensive assessment framework, in which biophysical, socio-cultural, and monetary values can be combined. We propose to use a framework where the importance of identifying an ecosystem’s capacity to provide services (supply side) and their social demand (demand side) are differentiated allowing the status of an ecosystem service to be influenced not only by the ecosystem’s properties but also by societal needs. We define the supply-side as the capacity of a particular area to provide a specific bundle of ecosystem services within a given time period, and the demand side as the sum of all ecosystem services currently consumed, used, or valued in a particular area. This framework can be applied for the management of watersheds with conflict over water ownership and use.
The Kiamichi watershed in southeastern Oklahoma provides a number of regulating, provisioning, and cultural ecosystem services to local populations, Oklahoma City, and the region. Many of these services are undervalued and declining in supply. The watershed is home to a diverse assemblage of freshwater mussels that provide water purification, areal biofiltration, nutrient cycling and storage, structural habitat, bioturbation of sediments, food sources for other organisms, and cultural resources. Periodic drought and water management practices over the past several decades have altered the periodicity and severity of low flows in the Kiamichi River to the detriment of mussels. For example, water releases from Sardis Dam on the Kiamichi were halted during the summer of 2011 to maintain water in Sardis Lake causing patchy drying of the river that killed hundreds of mussels and dramatically reduced the supply of the mussel-provided services mentioned above. We estimate that the 63 long-standing mussel beds between Clayton and Antlers on the Kiamichi below Sardis Dam filter 10 million L of water/year/km and that there has been a 60% loss of mussel biomass since 1992 reducing the supply of this and other services substantially. We are using this data in combination with social demand data in our ecosystem services framework to provide a more comprehensive estimate of market and non-market values and our future supply-side research is expanding to consider secondary consumer provided services.