Autumn turns over a new leaf as summer shows its staying power

After the last days of summer were played out in August, autumn was quietly ushered in early the following month. Later, Victorian meterologists were even more precise, pinpointing September 1 as the exact date when the season began.

However, this year the natural cycle has been delayed a little and no one seems quite sure when summer will give way to autumn.

According to information gathered by the Woodland Trust's Nature's Calendar, blackberries, still reeling from the harsh winter, are ripening much later than usual and the countryside's golden hue has been temporarily postponed.

For the last five years, sightings of the first ripe berries have peaked in the first week in August. By this time last year, the Woodland Trust had more than 1,000 reports, but this summer things have been suspiciously quiet.

The survey, which feeds into records dating back to the 1700s and studies the timings of common seasonal events, has so far received just 81 reports, with most in the south and none further north than Leeds.

"It's not just blackberries," says project manager Dr Kate Lewthwaite. "Rowan berries are also late fruiting, with just 44 records for first fruit compared with 808 by the same time last year.

"Flowering was delayed in many species due to the coldest winter for 30 years and this has had a knock-on effect on fruiting.

"We're some way behind with lots of unripe fruit still on the bushes, and the best still to come.

"For the last few years the bulk of observations have been recorded by the end of the first week in August. However, seeing as we are already past that date and have very few records, it is becoming increasingly clear that autumn could well be late this year. Just how late we won't know until the end of the season."

And it is not just the berries which are putting the brakes on seasonal change. Just two records have been received of the first beech leaves to turn – generally the first trees which begin to change colour – compared with 116 at the same time last year.

However, those hoping the survey might be a sign the effects of global warming have gone in reverse will be disappointed.

"What we've found in the last 30 years with climate change, is the growing season for lots of species has been extended and – leaving this year aside – things are coming out earlier and leaves are hanging around on trees later.

"As long as it is still warm and there is plenty of water, there is no reason for trees to start packing up for the winter," adds Dr Lewthwaite. "With access to detailed historical records, we honestly believe that climate change is the biggest single threat to what little remains of our ancient woodland heritage."

The practice of noting down the timings of natural events, now known as phrenology, dates back to 1736 when Robert Marsham began recording his own Indications of Spring on his family estate in Norfolk. Over the centuries, Marsham's work has been added to by subsequent generations of citizen scientists dedicated to mapping their own specific parts of the country.

While this year autumn has been delayed, recent analysis of information collected by everyone from Victorian vicars to modern day dog workers has shown that Britain's plants are flowering five days earlier for every 1C rise in temperature.

"The findings are a wonderful endorsement of the power of citizen science to help provide answers to the kind of questions which demand data collection on a vast scale," says Richard Smithers, senior conservation adviser at the trust. "The records which have been amassed over the last 250 years are a simple, but robust index of how the natural world is responding to climate change.

"And we have still barely scratched the surface of the power of the internet as a way of harnessing people power to further our

understanding of the natural world that has previously been beyond our grasp."