IUCN Red List of Ecosystems
Dr Jon Paul Rodriguez, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Venezuela
There are two fundamental conceptual differences between risk assessment for species and risk assessment for ecosystems: the endpoint of the decline and the definition of the assessment unit. When the last individual of a species dies, the species is unequivocally extinct. The ecosystem analog of species extinction is collapse, but thresholds of collapse are not absolute, and at least in theory collapse may be reversible: as long as all individual components of an ecosystem persist somewhere in the world, it could potentially be reassembled. Assessment units for species red lists rely on the platform provided by taxonomy, but no equivalent hierarchical, nested, widely agreed system for classification of ecosystems exists. Therefore, the burden of defining units for ecosystem risk assessment rests on the assessors and thematic groups of specialists, and requires the provision of relatively detailed information on their characteristic native biota (the primary target of ecosystem risk assessment), distinctive biotic and abiotic features, and precise spatial boundaries. The assessment of risk of collapse begins with definition of an ecosystem process model and quantification of a series of measures of extent (past and present), substrate condition, and state of biotic interactions. By systematically contrasting these measures against a set of criteria, assessors are able to assign categories that reflect increasing levels of risk of collapse.
Losing history: how extinctions prune the tree-of-life
Dr Jonathan Davies, McGill University, Canada
Current estimates suggest that we are losing species at rates unprecedented since the mass extinction events recorded in the fossil record. In vertebrates, species traits, such as body size, fecundity, and geographic range are important predictors of vulnerability, and often show a strong phylogenetic signal. Therefore, if a particular species is threatened with extinction it is likely that its close evolutionary relatives are also vulnerable because they share similar traits conferring sensitivity to extinction drivers. In mammals and birds, this non-random pattern of extinction has been argued to elevate the rates of loss of evolutionary history from the vertebrate tree-of-life. In contrast, patterns of species loss in plants are inconsistent with a simple trait-based model of extinction; rather, there is evidence that the most vulnerable species are found in species rich and more rapidly diversifying clades. If this is the case for plants more generally, extinctions might result in little loss of plant evolutionary history. However, loss of evolutionary history, measured in millions of years, might not reflect losses of functional diversity, which is critical for maintaining ecosystem processes. Under a punctuated model of evolution, in which trait differences accrue in bursts at speciation, the number of branches lost is more important than their summed lengths, and the impact of extinctions might be much greater for both plants and vertebrates.
The IUCN Sampled Red List Index for Plants
Dr Neil Brummitt, Natural History Museum
The IUCN Sampled Red List Index (SRLI) is a policy response by biodiversity scientists to the need to measure the status and trends of the world’s diminishing biological diversity. Assessments of plant species for the SRLI project rely predominantly on herbarium specimen data from natural history collections, in the overwhelming absence of accurate population data or reliable distribution maps for the vast majority of plant species. This creates an issue for re-assessing these species in order to measure genuine changes in conservation status and thus re-calculate the SRLI. However, the same specimen data identifies precise localities where threatened species have previously been collected and can be used to target ground-truthing expeditions to collect population data for SRLI plant species. Here we outline a strategy for prioritising ground-truthing efforts in order to apply a wider range of IUCN Red List Criteria to plant assessments for a more robust estimation of the SRLI, and further examine the extent to which the SRLI also captures change in genetic diversity for plant species.
Why and how might phylogeny and evolutionary processes be reflected in the identification of key biodiversity areas?
Professor Thomas Brooks, International Union for Conservation of Nature, Switzerland
In 2004, the ~200 government and government agency members and ~1,000 NGO members of the International Union for Conservation of Nature requested that the union consolidate standards for identification of significant sites for biodiversity. After extensive consultation, this process of consolidation is now nearing completion, for launch at the November 2014 World Parks Congress. The draft umbrella standard builds heavily on existing approaches (e.g., Important Bird Areas, Important Plant Areas, Alliance for Zero Extinction) and their criteria (e.g., for threatened and restricted-range species, biome-restricted assemblages, and congregations), although it proposes revision of the structure and level of thresholds for global significance of sites identified under these criteria. The draft also proposes several additional criteria, for threatened and restricted-range ecosystems, exceptional ecological integrity, and outstanding ecological and evolutionary process. For the latter of these, despite recognition of the potential importance of consideration of phylogeny and evolutionary processes in the identification of significant sites for biodiversity, it has not yet been possible to propose thresholds which could allow such a criterion to become operational. Here, we review both the rationale for why such a criterion is desirable, and the challenges for putting it into practice. We conclude by suggesting priority research towards resolving these challenges, while recognizing properties of the other draft criteria, which may de facto address phylogeny and evolutionary processes in the interim.