By Jeremy Lovell
    Reuters

    Tuesday 12 September 2006

    London - Thousands of plant species are being pushed to the brink of extinction by global warming, and those already at the extremes are in the greatest danger, a leading botanist said on Tuesday.

    Paul Smith, head of Britain's Millennium Seed Bank, said the drylands of the world which cover 40 percent of the earth's surface and are home to more than one-third of the population faced the bleakest future.

    "In the southern hemisphere the plants can either go up or south. But in South Africa's Cape they can't do either, so the 8,000 unique species of fijnbos (indigenous vegetation) there are a real worry," he told Reuters on a visit to London's Kew Gardens.

    Smith's team is on target to have sorted and stored seeds from 10 percent of the world's plant species by 2010 in a race against time as global temperatures rise due to burning fossil fuels for transport and power.

    "The trouble is that when we started collecting it was generally agreed that there were 242,000 plant species. But now some people believe it could be as high as 400,000.

    "We really need to find out just what is out there before it has gone forever," he said, noting that on Robinson Crusoe island off Chile scientists found there had been eight extinctions in just the past decade.

    But it is not just in the southern hemisphere that climate change is creating radical changes in the environment as warm weather expends steadily northwards, bringing with it new species and threatening the local vegetation.

    In England not only had the climate already changed to favor drought-resistant Mediterranean plant and tree species, it had brought with it insect pests that were previously unknown there because they would not have survived the winter frosts.

    Tony Kirkham, tree specialist at the world famous Royal Botanical Gardens at Kew in southwest London, noted that the Macedonian Leaf Miner moth had invaded in recent years and was attacking - and eventually killing - Horse Chestnut Trees.

    While drought stress and pest attack was starting to cripple some indigenous species, dry climate trees like Eucalyptus from Australia, Turkish Hazel and the Sweetgum from the United States were finding the new growing climate very much to their liking.

    Climate Change Minister Ian Pearson said scientists predicted that in Britain alone rainfall would have halved by 2080, with hotter, drier summers and warmer, wetter winters with frosts - essential to the natural cycle - a rarity.