The authors say that their estimates — which focus on 'missing' tropical data — suggest that up to half of the world's plant species could face extinction. The figure normally quoted for is just 13 per cent — a "serious underestimate", they say.
The World Conservation Union (IUCN), which publishes the recognised standard 'red lists' of threatened species, acknowledges that its data has "major gaps" that are "particularly accentuated in the tropics".
But American botanists Nigel Pitman and Peter Jørgensen argue that by using the number of plant species endemic to a country as a guide to the number of species under threat in that country, they have a achieved a more accurate estimate.
"Data on national-level endemism in the tropics are far from perfect, but they are consistently better than data on threatened species," say the authors.
They found, for example, that 83 per cent of plant species endemic to Ecuador qualify as globally threatened under IUCN criteria.
The authors warn that without more accurate evaluation of the status of plant species — particularly in biodiversity hotspots — it will be hard to assess whether conservation efforts are succeeding.
"Only with species-by-species information … will conservationists be able to monitor and prevent the large-scale plant extinctions foreseen to occur in the tropics in this century," they say.
© SciDev.Net 2002
Photo credit: C.Ulloa / Missouri Botanical Garden