Daniel P. Faith

“Nature’s contributions to people” (NCP) is an important expansion beyond the standard ecosystem services framework, particularly as a pathway to better address global/regional biodiversity values. NCP18, “maintenance of options,” refers broadly to the capacity of ecosystems, habitats, species, or genotypes to keep options open to support a good quality of life. “Biodiversity,” interpreted as living variation, is an important, but under-appreciated, aspect of “maintenance of options.” IPBES refers to “the “option values of biodiversity,” that is, the value of maintaining living variation in order to provide possible future uses and benefits.” IPBES assessments include biodiversity option value, and use phylogenetic diversity (PD) as an indicator of change in status of NCP18. At the same time, IPBES notes the need for greater appreciation of option values of biodiversity. Popular ecosystem services framings forget the long history of consideration of these global benefits of biotic diversity to humanity, and their normative links. Popular ecological definitions mean that many current valuations of “biodiversity” neglect the benefits of biodiversity-as-variety. Economic valuations of “biodiversity” typically have focused on ecosystem aspects, not variety; related ecosystems framings value “biodiversity” with a focus on those critical elements relating to functioning of ecosystems. Greater appreciation of biodiversity option value and NCP18 may depend on clearer messaging from academia, better highlighting of the link between biodiversity and intergenerational justice, and greater communication of stories of past surprising discoveries of benefits from species that highlight biodiversity as an ongoing source of future benefits. An important pathway for better appreciation of insurance and investment benefits of variety is to understand and communicate the reasons why we value these benefits from variety. Biodiversity-as-variety is valued because we care about the welfare of future generations.

Faith, D. P. 2018. Avoiding paradigm drifts in IPBES: reconciling “nature’s contributions to people,” biodiversity, and ecosystem services. Ecology and Society 23(2):40. https://doi.org/10.5751/ES-10195-230240

The phylogenetic diversity measure, (‘PD’), measures the relative feature diversity of different subsets of taxa from a phylogeny. At the level of feature diversity, PD supports the broad goal of biodiversity conservation to maintain living variation and option values. PD calculations at the level of lineages and features include those integrating probabilities of extinction, providing estimates of expected PD. This approach has known advantages over the evolutionarily distinct and globally endangered (EDGE) methods. Expected PD methods also have limitations. An alternative notion of expected diversity, expected functional trait diversity, relies on an alternative non-phylogenetic model and allows inferences of diversity at the level of functional traits. Expected PD also faces challenges in helping to address phylogenetic tipping points and worst-case PD losses. Expected PD may not choose conservation options that best avoid worst-case losses of long branches from the tree of life. We can expand the range of useful calculations based on expected PD, including methods for identifying phylogenetic key biodiversity areas.