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Sampled Red List Index for Plants

Monitoring conservation status and global trends for plant species worldwide.
SRLI interactive map showing hotspots of threatened plants.

The Sampled Red List Index for Plants was established as part of Kew’s response to the 2002 decision by the parties to the Convention on Biological Diversity to reduce the rate of loss of biodiversity by 2010. Kew was an active participant in the scientific debate which followed the adoption of this high profile target, which presented an opportunity for Kew to translate into action its 2001 strategic commitment to increase the relevance of Kew science to current policy issues. The Red List Index method, which was at that time only in use for vertebrate groups, was considered the optimum approach for Kew’s plant-based contribution because of its firm foundation in the internationally recognized IUCN Red List categories and criteria and because the individual assessments of plant species from which the Index is constructed would be of value in their own right in guiding conservation action for thousands of plant species.

While the Red List Indices for birds, mammals and amphibians rely on repeated assessments of the conservation status of all species in the group in question, the far greater number of known plant species (c. 380,000) makes repeated comprehensive assessments impractical over the 5-10 year timescales in which we wish to detect change. A sampled approach was therefore adopted, with Kew staff actively contributing to the development of Sampled Red List Index methodology. All known gymnosperms were included, complemented by a sample of 1,500 species drawn for each of the other groups to be treated for the SRLI for plants: bryophytes, pteridophytes, monocots and legumes. Legumes were chosen to represent other flowering plant families in the absence of a comprehensive species list from which a random sample could be drawn.

During Phase 1 (2006-2010) IUCN Red List assessments for the sampled species were prepared, based on herbarium specimen data, GIS analysis, published literature and, where available, expert input. Assessments are published on a scratchpad resource 'Sampled Red List Index for Plants' to facilitate comments/corrections as well as being submitted to IUCN for inclusion in the Red List. The results of Phase 1 were presented as the First Report of the IUCN Sampled Red List Index for Plants, published to coincide with the tenth Conference of the Parties to the Convention on Biological Diversity in Nagoya.

Plants Under Pressure - A Global Report (2010)

Plants Under Pressure - A Global Report (2012)

Pie chart showing percentage of plants classed as endangered: 4% Critically Endangered. 7% Engandered. 11% Vulnerable, 10% Near threatened, 63% Least Concern, 5% Data Deficient.
One in five plants are threatened with extinction (2010). [Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD)]

The format was designed to engage national policy-makers and environment correspondents worldwide, and the launch resulted in unprecedented national and international media coverage (c. 300 high profile media articles and > 100,000 blogs). The SRLI was the first study to tackle these headline questions from a globally representative sample of plant species, and it allowed policy-makers to understand which plants are most threatened, where and why to a degree of detail that has so far only been possible for vertebrates. For the first time we are now able to say that plants are more threatened than birds and as threatened as mammals worldwide, and to appreciate that conversion of natural habitats to agricultural use directly impacts one in three threatened plant species.

Results from Phase I mark the starting point for the IUCN Sampled Red List Index for Plants. They provide the baseline against which future changes can be tracked - and show clearly that urgent action is needed if we are to avoid losing one in five of our plant species. We now have a snapshot of the current status of plant diversity, but these species will need to be regularly reassessed if we are to truly understand the changing status of the world’s plants, and indeed global biodiversity overall. Phase II of the IUCN Sampled Red List Index for Plants aims to mobilise an extensive global network of botanists, academics and conservationists to establish an international monitoring scheme. Species will be assessed in the field as part of ongoing monitoring efforts so threats to plant survival - as well as the overall trend in the status of plants over time - can be understood and documented. Targeted fieldwork will be essential to update our information, especially for those plants whose status is declining rapidly as their environment is changing.

Project partners and collaborators

Natural History Museum, London
Zoological Society of London

Missouri Botanical Garden

Project funders


Charles Wolfson Trust
Defra (International Sustainable Development Fund)
Esmée Fairbairn Foundation
World Collections Programme


Rio Tinto

Annex material

Key publications 2006-2011

  • Rivers, M.C., Brummitt, N.A., Meagher, T.R. & Nic Lughadha, E. (2011). How many herbarium specimens are needed to detect threatened species? Biological Conservation 144: 2541-2547. Available online.
  • Rivers, M. C., Bachman, S., Meagher, T. R., Nic Lughadha, E. & Brummitt, N. A. (2010). Subpopulations, locations and fragmentation: applying IUCN red list criteria to herbarium specimen data. Biodiversity and Conservation 19, 2071-2085. Available online.
  • Plants under pressure a global assessment. The first report of the IUCN Sampled Red List Index for Plants. Royal Botanic Gardens, Kew, UK. 2010 and 2012
  • Brummitt, N., Bachman, S. P. & Moat.J. (2008). Applications of the IUCN Red List: towards a global barometer for plant diversity. Endangered Species Research 6:127-135. Available online.
  • Baillie, J.E.M., Collen, B., Rajan, A., Akcakaya, H.R., Butchart, S.H.M,, Brummitt, N., Meagher, T.R., Ram, M., Hilton-Taylor, C. & Mace, G.M. (2008). Toward monitoring global biodiversity. Conservation Letters 1: 18-26. Available online.