It is an unseasonably warm day in September, at the end of a very long, very hot summer. Kevin Martin is sitting in the passenger seat of a golf buggy, staring at a stand of withering beech trees in the middle of Kew Gardens, in south-west London. Where there should be a show of dancing green leaves, there are only wisps of brown curls amid bare branches.
Martin is responsible for tending and curating the 11,000-strong tree collection at Kew. But successive heatwaves and a severe drought have been catastrophic for his wards this summer. Across Kew, branches stand bare against clear blue sky and leaves crunch under the feet of visitors, as the stressed trees shed their leaves early in an effort to survive the drought and heat.
Shifts in the jet stream are behind Europe’s long heatwaves Martin estimates that at least 400 trees, if not more, will have died this summer at Kew, equal to the record mortality seen in 2022. Because they can’t deal with the heat.” It isn’t just in Kew Gardens that the trees are struggling. It is the same story across south-east England.
Trees in urban areas are worst affected, because alongside the drought, they are battling higher air temperatures, pollution, soil compaction and other urban stressors. Mature city trees are more resilient, but younger specimens are in dire straits, threatening efforts to provide more shading and greenery in cities. The charity Trees for Cities says half of the young saplings it has planted in London in the past year died over the course of this summer.
Survival rates should normally hover around 80 to 90 per cent. This summer has been very intense for the trees and very stressful for our team.” The loss of trees in parks and streets doesn’t just mean a loss of beauty. London’s trees help to cool the city by up to 5°C, research from environmental charity Friends of the Earth shows, and provide vital shading for humans and wildlife on hot days.
Things will only get worse for city trees as summers become hotter and drier. England’s climate is shifting rapidly, and the south-east is moving from a moist, temperate climate to a semi-arid one, says Martin. Summers will become hotter, but rainfall levels will flatline.
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