Trade-offs between ecosystem services along gradients of tree species diversity and values

Trade-offs between incommensurable values of services are a challenge to the implementation of the ecosystem services framework. The International Platform of Biodiversity and Ecosystem Services (IPBES) recommends pluralistic valuations of ecosystem services that include intrinsic, instrumental, and relational values. To understand how value pluralism may affect trade-offs between ecosystem services, we conducted a study quantifying ecosystem service proxies along a tree species diversity gradient in plantation forests in the coastal Pacific Northwest, USA. Further, we developed four frameworks emphasizing different bundles of ecosystem services based on how the services clumped within a matrix of value types and level of social organization at which benefits are likely to accrue. We then determined tree species compositions that optimized ecosystem services emphasized under the four frameworks. Some ecosystem services responded in sync, but we found trade-offs between provisioning services with primarily instrumental value and cultural services with relational values. Most single ecosystem services were maximized by monocultures. In contrast, high levels of tree species diversity supported the largest variety of value types. We hypothesized that biodiversity may be important not just for increasing ecosystem functions and services, but also for value pluralism.