One-fifth of world's plants at risk of extinction
|
COMMENTS 
A first ever comprehensive study of plants finds that 22% of all species are at risk. Species in tropical rainforests more so
One-fifth of the world’s plants -- the foundation of all life on earth -- are at risk of extinction, a recent study concludes. Researchers sampled almost 4,000 species and concluded that 22% should be classified as “threatened” -- the same alarming rate as for mammals. A further 33% of species were too poorly understood to be assessed. There are an estimated 380,000 plant species in all, and many are victims of habitat loss -- typically the clearing of forests for agriculture.
The analysis comes from the Royal Botanic Gardens at Kew, the Natural History Museum, and International Union for the Conservation of Nature (IUCN). The study, known as the ‘Sampled Red List Index for Plants’, is an attempt to provide the most accurate assessment of the situation so far.
Previous studies have focused on the most threatened plants or particular regions. This one instead sampled species from each of the five main plant groups; its authors argue that as a result their conclusions are more credible.
The report comes ahead of the UN Biodiversity Conference in Nagoya, in Japan, next month where ministers are due to discuss why conservation targets keep being missed.
Launching the findings, Kew’s director, Professor Stephen Hopper, said the study would provide a baseline from which to judge future losses. “We cannot sit back and watch plant species disappear -- plants are the basis of all life on earth, providing clean air, water, food and fuel. Every breath we take involves interacting with plants. They’re what we all depend on.”
The study investigated the key types of plants, including mosses, ferns, orchids and legumes like peas and beans. The fear among botanists is that species are being wiped out before they can be properly researched, potentially losing valuable medicinal species.
Plant-based remedies are the only source of healthcare in the world’s poorest countries and have proved essential in combating conditions including malaria and leukaemia. Another concern is that we have become dependent on a narrow range of plants with a limited genetic base.
Scientists randomly selected 7,000 species from across the major plant groups as a representative sample of the estimated 380,000-400,000 so far known to science. Of these, 3,000 were found to have too little information to begin making a proper assessment -- a result that was expected and so built into the selection process.
The remaining 4,000 species were assessed and the level or risk based on a combination of the absolute number of plants estimated in the wild, the known decline, and total area in which they are thought to live.
Of the 4,000, 63% were found to be of “least concern”, 10% “near threatened”, 11% “vulnerable”, 7% “endangered”, and 4% “critically endangered”. Another 5% were rated “data deficient”.
The proportion of plant species deemed at risk is similar to that of the IUCN’s red list for mammals, worse than that for birds (less than 10% at risk) and better than the number for amphibians (more than a quarter under threat).
Nearly two-thirds of threatened plant species are found in tropical rainforests, five times the proportion for the nearest other habitats -- rocky areas, temperate forests and tropical dry forests. This is because of their huge density of biodiversity and widespread risks of logging and clearance for agriculture, said analysts.
Previously, the red list for plants contained assessments for a greater number of plants -- about 12,873, or 3% of known species -- but was not considered representative because scientists had focused on at-risk species so that they could get attention and funding for conservation.
Source: The Guardian, September 29, 2010
http://www.bbc.co.uk, September 29, 2010