Sampled Red List Index for Plants

Monitoring conservation status and global trends for plant species worldwide

The SRLI interactive map showing hotspots of threatened plants.

The Sampled Red List Index for Plants was established as part of RBG 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. RBG 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 RBG Kew staff actively contributing to the development of Sampled Red List Index methodology. All known gymnosperms were included complemented by a sample of 1500 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 (http://www.kew.org/ucm/groups/public/documents/document/kppcont_027694.pdf).

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.

We are now ready to build on the results of Phase 1 of the SRLI for plants, which represented the culmination of five years work by a team of staff at Kew and the Natural History Museum, and with contributions by many volunteers. We have a sound baseline against which trends in the status of plants worldwide can be reported; now we need to measure how these trends change over time. Phase 2 will require work on an even greater scale than that already completed, including extensive fieldwork and relying more on an international network of collaborators, with a view to providing a preliminary overview of trends by 2015 and more detailed reassessment by 2020. Given the scale and complexity of Phase 2, a feasibility study is planned for 2012 to scope in more detail the methods and resources required for the full reassessment. Outputs of the feasibility study will include a robust business case with a costed work plan for Phase 2, which is of critical importance, a substantial new contribution of ground-truthed assessments for the IUCN Red List, and models for new tools to support assessors in the field.

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.
• 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.
• Plants under pressure a global assessment. The first report of the IUCN Sampled Red List Index for Plants. Royal Botanic Gardens, Kew, UK. 2010.
• 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.
• 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.