Ecosystems on the EDGE: Ecologically Distinctive Globally Endangered

The IUCN Red List of Ecosystems provides red list ratings for threatened ecosystem types. How will this be used for conservation planning?

The IUCN Red List of Ecosystems (http://www.iucn.org/about/union/commissions/cem/cem_work/tg_red_list/  ) is providing red list ratings for threatened ecosystem types.

Planning and decision-making for the conservation of such ecosystems, and their biodiversity, needs to take into account the fact that ecosystem types overlap in their component species. Elsewhere, I had proposed one solution to this problem, based on ED analysis (see Enhancing Ecosystem Types Using Museum Data and ED Models ).

An alternative is to summarise the species-compositional overlap using hierarchical clustering of the types. We can estimate overlap using GBIF and other museum collections information. For this hierarchy or "tree" , we can assess changes in the status of types using a measure normally applied to gains and losses of species on phylogenetic trees. The PD ("phylogenetic diversity"; Faith 1992) measure normally uses phylogenetic patterns to predict feature diversity of sets of species. The total PD of a given set is the total phylogenetic branch length spanned (represented) by its member species.

For the hierarchy of ecosystem types, a subset of types with greater PD represents more species (see early work by Woinarski et al 1996*). For applications of PD to the Red List of Ecosystems, we also incorporate probabilities of loss, derived from the Red List status values.  This provides "expected PD" calculations analogous to those recommended for the EDGE (“evolutionarily distinctive, globally endangered”) threatened species program (see Faith 2008, Con Bio).

Using this probabilistic PD approach, threatened ecosystem types that are more distinctive (little species-compositional overlap with other types) would have higher conservation priority. This is the basis for an “EDGE” program (“ecologically distinctive, globally endangered”), analogous to the program for threatened species.

Current Red List status of ecosystem types provides an expected PD value interpreted as expected relative number of species. Planning can assess priority conservation actions, taking costs into account.

* Woinarski, J.C.Z., Price, O. and Faith, D.P. (1996) Application of a taxon priority system for conservation planning by selecting areas which are most distinct from environments already reserved. Biological Conservation Volume 76, Issue 2, Pages 147–159
 


Dr Dan Faith , Principal Research Scientist
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