Drought and Heat Bring ‘False Autumn’ to UK Trees
People across the UK have noticed trees changing color and losing their leaves early, but this isn’t because of a sudden cold snap.
“It’s giving the appearance that we’re already in autumn, but the days are too long for those natural autumn processes to begin,” senior horticultural advisor at the Royal Horticultural Society Leigh Hunt told BBC News. “Physiologically, the plants are not responding to autumn conditions; that’s why we term it loosely as ‘false autumn.'”
The UK is in the midst of a summer of extreme weather. It experienced its first-ever temperature reading higher than 40 degrees Celsius in July, something the international team of scientists from World Weather Attribution said would have been “extremely unlikely” without human-caused climate change. The high temperatures have been accompanied by drought, with some areas experiencing their driest July since 1935, The Independent reported. Drought has also been officially declared in eight out of 14 English areas.
While there are no studies linking current drought and the climate crisis in the UK, summers are projected to become drier in the future, and this trend is predicted to be even more dramatic in a high-emissions scenario, according to the UK Met Office.
The hot, dry weather is having an impact on trees, and Hunt told BBC News that this was one of the worst years for trees he had witnessed in 45 years.
“It’s stressing them so much that that cycle of photosynthesis has just not been able to carry on in the tree, and the trees are enacting their hormones that they use in autumn to just retract and ensure their survival,” Rosie Walker of the Woodland Trust said in an interview with BBC Radio 5 Live.
Walker said the trees could continue to survive like this for a few years.
“But it is going to start impacting our trees if we’re not very careful,” she added.
Hunt also said that older trees with a large root network could survive drought, but younger trees planted in poor soil could die.
The two species currently most impacted by this phenomenon are silver birch and rowan, Walker said. The Woodland Trust recorded the first leaf turn for silver birch on August 12, “which is incredibly early,” Walker added.
In addition, the Woodland Trust has recorded other unusually early autumn signals, including the earliest ever report of ripe blackberries, on June 28, as BBC News reported.
“The record-breaking heat we have just experienced has helped bring on a number of early autumn events,” the Woodland Trust’s Fritha West told BBC News.