Over half of the carnivorous plant species assessed by the International Union for the Conservation of Nature (IUCN) are listed as threatened (i.e. vulnerable, endangered, or critically endangered), but the threats to carnivorous plants have not previously been quantified systematically. In this review, we quantify the conservation threats to carnivorous plant taxa worldwide. Using the IUCN Red List, a literature search of Web of Knowledge, and the National Red Lists database, we collected data on the threats to 48 species of carnivorous plants from nine genera. The most common threat was habitat loss from agriculture, followed by the collection of wild plants, pollution, and natural systems modifications. A principal coordinate analysis revealed that species within a genus often faced similar threats, and an indicator species analysis found positive associations among species in the genus Sarracenia and agricultural activities, over-collection, invasive species, and pollution. Future research should further quantify the effects of pollution on carnivorous plants, and more thoroughly examine the potential role of carnivorous plants as indicator species for wetland health. More research is also needed to quantify the extinction risk for many carnivorous plants, as presently only around 17% of species have been assessed by the IUCN. Ensuring the conservation of carnivorous plants will help maintain the important ecosystem services they provide and prevent secondary extinctions of specialist species that rely on them. (C) 2011 Elsevier Ltd. All rights reserved.
