Climate change is reshaping the landscape of Britain as rising temperatures allow orchids and ferns to flourish in the north, while other species retreat to cooler conditions on high land and mountainsides.
The conclusion, published today in a comprehensive survey of the nation's flora, suggests that the changing climate has already brought about a rapid and dramatic shift in the country's plantlife, a trend researchers say will be exacerbated by future warming.
Volunteers working for the Botanical Society of the British Isles and the charity Plantlife recorded more than 200,000 plants in patches four kilometres square around the country and found the number and distribution of one third of all species had changed substantially since an earlier survey in 1987.
Many plants have spread north and west to capitalise on the milder conditions warming has brought, with several species of orchid and fern, such as the bee orchid and hart's tongue fern, recorded twice as frequently as in the previous survey.
Other species, such as the lesser butterfly orchid and mountain pansy, which flourish in cooler climates, suffered declines. "It's easy to pick out the species that have fared well because they have moved into new areas, but the losers are harder to spot," said Katherine Stewart of Plantlife. "We know plants that flourish in moist, cooler conditions, such as moorland and mountain species, are likely to suffer. They may retreat further north or up mountainsides, but some may hang on for a while and then go suddenly."
According to the survey, the mean central England temperature for 1987 was 9.05C, compared with a mean of 10.51C in 2004. The report claims that the rising temperatures have caused most disruption to plants with heavy seeds because they are unable to disperse over long distances, and so re-establish themselves far from their traditional habitats. "The ferns have tiny spores and they are carried a long way, the orchids have tiny seeds and there are the plume seeds of the daisy family and their seeds can be carried long distances," said Michael Braithwaite of the Botanical Society of the British Isles. "But a lot of the more traditional wildflowers don't get around easily; they have heavier seeds and discard much less freely, and in the long term that is a worry."
Goldenrod, a member of the dandelion family, has declined 15% in the survey, with moorland species such as lousewort also suffering notable losses.
Much of Britain's plant life is under threat from the use of fertilisers by the agricultural industry, which artificially raises the level of nutrients in soils, a process called eutrophication, and some species can take over patches of ground, leading to the die-off of less hardy species.
One surprising aspect of the report is the speed with which plants have responded to climate change. "We are going to see a lot of extinctions, particularly of species that are not able to move quickly enough," said Ms Stewart.
Mr Braithwaite said the level of climate change Britain had experienced had been generally positive for plantlife, with most species extending their habitats. "The concern is that if you multiply the temperatures up, there might well be more of a problem in the future," he said.
Winners and losers
How Britain's flora is coping with climate change
· Bee orchid (Ophrys apifera)
· Pyramidal orchid (Anacamptis pyramidalis)
· Hart's tongue fern (Phyllitis scolopendrium)
· Prickly lettuce (Lactuca serriola)
· Lesser butterfly orchid (Platanthera bifolia)
· Goldenrod (Solidago virgaurea)
· Mountain pansy (Viola lutea)
· Lousewort (Pedicularis sylvatica)
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