Threatened species lists are used at global, national and regional scales to identify species at risk of extinction. Many species are listed due to restricted population size or geographic distribution, and decline is often inferred rather than quantified. Vascular plants comprise over 70% of nationally listed threatened species, but there is an incomplete picture of which species are most at risk of extinction, where these occur and the factors behind their declines. We compiled published information and the best available field knowledge including 125 expert interviews to identify declining and at risk species. The candidate list comprised 1135 taxa, which were mostly listed as Critically Endangered or Endangered under Federal and/or State legislation, but included 80 that are currently unlisted but considered to be highly threatened. In total, 418 taxa were assessed as having a documented, suspected or projected continuing decline. These were ranked based on extinction risk and magnitude of continuing decline, which suggest that 296 are at risk of extinction under current management regimes, including 55 at high risk of extinction. Declining and imperilled taxa are concentrated in a relatively small number of regions and habitats, and six threatening processes are driving the majority of declines. Field surveys and robust, repeatable monitoring are required to better inform population trends and extinction risk, as well as inform the status of almost 200 taxa that are potentially imperilled but poorly known. Identification of declining taxa can identify key issues for flora conservation across a continent, and allow for targeted and efficient recovery efforts.
Introduction to Conservation Genetics
