Green Plants in the Red: A Baseline Global Assessment for the IUCN Sampled Red List Index for Plants

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.

The Sampled Red List Index for Plants, phase II: ground-truthing specimen-based conservation assessments

“…Full IUCN Red List assessments have to date been completed and submitted to IUCN for almost four thousand (3990) species, from samples of pteridophytes, monocots and legumes from around the world and, supplementing the work of the IUCN Conifer and Cycad Specialist Groups, for all remaining gymnosperm species. Each of these assessments is either now available on the Red List or is in the process of being evaluated by IUCN [11]. It has not yet been possible to gather sufficient data with which to assess the remaining species from the sample; these are likely to be fully assessed as DD, although these DD assessments have not yet been formally submitted to IUCN as they do not contribute to the value of the index.…”

“…This is known as Goodhart's law [24] and could equally be true for any species listed on the Red List. However, due to the reliance of measures of habitat loss in order to satisfy the subcriteria under criterion B, any positive change in the status of SRLI species will also have a positive change on the status of many other species in the vicinity [11]. The future loss of peripheral populations of threatened species, representing a genuine change in conservation status, however, might be inferred from satellite imagery, on the assumption that an obvious loss of known habitat of that species will mean a corresponding extinction of local subpopulations.…”

Abundance and habitat-suitability relationship deteriorate in fragmented forest landscapes: a case of Adinandra griffithii Dyer, a threatened endemic tree from Meghalaya in northeast India

“…Nonetheless, anthropogenic activities such as over-exploitation, habitat destruction, and fragmentation of forest areas have substantially altered the natural landscapes affecting the distribution of species populations and habitats (Hansen et al 2013). These influences have brought at least one-fifth of the plant species to the brink of extinction (Brummitt and Bachman 2010), putatively affecting the AS relationship (Fischer and Lindenmayer 2007). The nature of the relationship in humanaltered landscapes is not clearly understood, and therefore deserves a detailed and systematic study.…”

Important Plant Areas: revised selection criteria for a global approach to plant conservation

“…Current estimates suggest one in five of the world's plant species is threatened with extinction globally (International Union for Conservation of Nature, IUCN Sampled Red List Index for Plants 2012; Sharrock et al 2014;Brummitt et al 2015;Bachman et al 2016). Despite commitments by the international community to halt biodiversity decline, for example through implementing the Convention on Biodiversity (CBD 1992) and the associated Aichi Biodiversity Targets (CBD 2012a), conservation efforts targeting plant diversity are often hampered by lack of suitable data for prioritising conservation action.…”