Green plants in the red : a baseline global assessment for the IUCN Sampled Red List Index for Plants

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.Publisher PDFPeer reviewe

Workpackage 9

<p>Numbers of species from the combined SRLI for Plants sample of gymnosperms, monocots, legumes and pteridophytes by IUCN Red List Category for each group of plants.</p

Red List Indices for birds, mammals, amphibians and corals (source: IUCN), with baseline values for crayfish [13], freshwater crabs [16], dragonflies & damselflies [17], reptiles [19] and plants (this study).

<p>Values for crayfish, freshwater crabs, dragonflies and damselflies, reptiles and plants are based on a sampled approach.</p

Numbers of species from the combined SRLI for Plants sample of gymnosperms, monocots, legumes and pteridophytes in each IUCN Red List Category by realm.

<p>Numbers of species from the combined SRLI for Plants sample of gymnosperms, monocots, legumes and pteridophytes in each IUCN Red List Category by realm.</p

Global map of average extinction risk of species per country from the combined SRLI for Plants sample of gymnosperms, monocots, legumes and pteridophytes.

<p>A. Number of species assessed per country. B. Percentage of assessed species that are threatened per country. C. Percentage of assessed species that are Data Deficient per country.</p

Threats to species from the combined SRLI for Plants sample of gymnosperms, monocots, legumes and pteridophytes, by number of plant species threatened.

<p>Individual species may be affected by more than one threat.</p