Mild autumn temperatures across the UK have caused trees to enter an "early spring," with experts warning of potential long-term harm to pollinators. Last month was warmer than average in all parts of the UK, marking October as the ninth consecutive month with above-average mean temperatures.
Horse Chestnuts Flowering Six Months Early
Chris Nichols, head of conservation outcomes at the Woodland Trust, said the mild weather meant horse chestnut trees were flowering and showing signs of next year's spring growth more than six months early. "It's crazy, everything is so out of whack," he said, adding that the early spring was particularly concerning for pollinators.
"Trees need to flower at a certain time of year so they're in sync with the insects. It's like an ecological mismatch and it's concerning in terms of the resilience of trees in the long term if they're out of whack with the other species that they rely on," Nichols explained.
Stress Response and Drought Effects
Dr Kate Lewthwaite, a citizen science manager at the Woodland Trust, said trees flowering early was a sign of stress. She suspected this was caused by drought, which prompted trees to shut down essential systems, similar to what happens in winter. "When the rains came, it encouraged them to start spring flowering out of season," she said.
During the extreme heat this summer, many trees underwent "early autumn," wilting and losing their leaves prematurely. Experts said England's ancient oak trees were dying as a result of high temperatures and drought, as trees and ecosystems struggle to adapt fast enough to the changing climate. Scientists have attributed the higher-than-average temperatures to the climate crisis, primarily driven by the burning of fossil fuels.
Kew Gardens Reports Confused Trees
Kevin Martin, head of tree collections at Kew Gardens, said trees at Kew's arboretum were also entering early spring. "The trees are all a bit confused because they've been so stressed this summer," he said. "Essentially trees went into dormancy this summer and then with these warm mild conditions they're now going back into growth, which means they won't have those buds again in the spring."
Martin said the true impact of this will not be known until spring 2028. He noted that trees have been so stressed this year that they have put on very little growth, especially in the south-east where the drought has been significant, leading to more failures during storms.
Lewthwaite warned that the whole tree may die or be forced to resprout from dormant buds on the trunk or branches, making the canopy much smaller next year. "We need to take action to help our woods and trees become more resilient to these challenges, such as rewetting woodland and slowing the flow of the rains we do get," she said.
