Abstract
Plants provide fundamental support systems for life on Earth and are the basis for all terrestrial ecosystems; a decline in plant diversity will be detrimental to all other groups of organisms including humans. Decline in plant diversity has been hard to quantify, due to the huge numbers of known and yet to be discovered species and the lack of an adequate baseline assessment of extinction risk against which to track changes. The biodiversity of many remote parts of the world remains poorly known, and the rate of new assessments of extinction risk for individual plant species approximates the rate at which new plant species are described. Thus the question ‘How threatened are plants?’ is still very difficult to answer accurately. While completing assessments for each species of plant remains a distant prospect, by assessing a randomly selected sample of species the Sampled Red List Index for Plants gives, for the first time, an accurate view of how threatened plants are across the world. It represents the first key phase of ongoing efforts to monitor the status of the world’s plants. More than 20% of plant species assessed are threatened with extinction, and the habitat with the most threatened species is overwhelmingly tropical rain forest, where the greatest threat to plants is anthropogenic habitat conversion, for arable and livestock agriculture, and harvesting of natural resources. Gymnosperms (e.g. conifers and cycads) are the most threatened group, while a third of plant species included in this study have yet to receive an assessment or are so poorly known that we cannot yet ascertain whether they are threatened or not. This study provides a baseline assessment from which trends in the status of plant biodiversity can be measured and periodically reassessed.
Highlights
Responding to global biodiversity targetsAt the tenth conference of the parties to the Convention on Biological Diversity (CBD) it was widely agreed that the 2010 Biodiversity Target of a significant reduction in the rate of biodiversity loss [1,2] had not been met [3]
For the following results presented by region and by habitat, and the figures summarising threats to plant species and proportions of threatened species by country, all four plant groups assessed have been analysed together (3990 non-Data Deficient (DD) species in total) rather than separately, so that the set of species within each region, habitat or country is large enough for there to be confidence in these results
Other factors contributing to the marked contrast in proportions of threatened species between temperate and tropical regions may include the greater rate of land-use change occurring in the tropics, and the fact that in temperate areas such as Europe much of the change in land use and habitat cover has occurred a long time ago and native forest has been replaced by stable grassland or heathland communities, the species left have depleted populations but are no longer declining
Summary
Responding to global biodiversity targetsAt the tenth conference of the parties to the Convention on Biological Diversity (CBD) it was widely agreed that the 2010 Biodiversity Target of a significant reduction in the rate of biodiversity loss [1,2] had not been met [3]. Baseline values for a Sampled Red List Index have already been calculated for several large but under-assessed groups such as freshwater crabs [16], dragonflies and damselflies [17] and reptiles [18], and work is progressing for butterflies and moths [19] and other groups, providing a better representation of the extinction risk of biodiversity as a whole; from such a baseline, trends can be estimated once these samples have been re-assessed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
