Species at risk as experts predict demise of winter

Autumn is likely to arrive later and last longer than before, a study of plants and animals in Britain's woodlands has revealed. Spring, meanwhile, is coming earlier and winter is close to disappearing.

For centuries people have been able to predict the timing of the seasons by the arrival and departure of birds, the flowering of plants and fruits, and the shedding of leaves or sprouting of green shoots.

But, according to findings from the conservation charity the Woodland Trust and the Centre for Ecology and Hydrology changing weather patterns have caused the seasons to become muddled. Many species have become endangered by traditional events thrown out of sequence.

More than 17,000 volunteer phenologists, devoted to studying the timing of natural seasonal events, have found conclusive evidence that spring no longer begins in March and autumn continues well beyond October, creating serious problems for wildlife.

"Last year oak trees weren't bare until 4 December and whereas autumn used to be September, October and early November it seems to be increasingly stretching into early December, which is a frightening prospect," a spokesman for the Woodland Trust said.

"It means that winter, traditionally a time when nature rests, is being squeezed out as spring is happening sooner."

He said there had been reports of snowdrops emerging in November and warned that without a winter, the complex relationships between species would be disturbed. "We are looking at a very grim picture for the future," he said.

The trust's report says temperatures from January to April of up to 3.2 degrees celsius above the average led to almost every characteristic of spring happening up to three weeks earlier than in 2001.

Insects such as bumble-bees and butterflies arrived three weeks early, while plants flowered two weeks ahead of their usual time and many birds, including the turtle dove, arrived a week earlier than normal. Autumnal events this year are likely to arrive several days later than average.

Jill Attenborough, the phenology project manager for the trust, said: "There has been quite a steep change in the way things are responding since the late 1950s ... as a result of climate change. Spring 2002 was a record two degrees warmer than the previous year. That gave us a good insight into what is going to happen with climate change and how nature responds from year to year."

She said different species responded to climate change at different rates. "Insects can speed up their life cycles but birds are stuck with having to wait for their eggs to hatch and by the time the chicks emerge the food source they depend on is no longer around in sufficient quantities. Relationships which have evolved over thousands of years are being thrown out of kilter and are beginning to fall apart," Ms Attenborough said.

"We have already seen that the competition between oak and ash trees is changing. Oak is responding faster and coming into leaf earlier than ash which means it has a longer growing season and a chance to grab the light and shade out other species."

The trust is looking for more volunteers to record seasonal events, however minor – even down to noting the dates on which they cut their lawn. The rising temperatures mean that grass has been growing for longer periods. In some parts of the South, people have to cut their lawns all year round.