Why our trees are too ‘stressed out’ to display beautiful autumn colours this year

Become an Independent member to bookmark this article Want to bookmark your favourite articles and stories to read or reference later? Start your Independent Membership today. Join today Already a member? Log in U sually, at this time of year, autumn is in full swing . Spring may have that whole “look-at-me”, new life thing going on – all those glossy green leaves and flowers bursting into bloom – but its pumpkin-spiced cousin arguably puts on a better show . As the seasons change, the leaves change with them, putting on a fiery display of oranges, yellows and reds that pop all the brighter against a crisp blue sky in the waning, buttery light. But not this year. Perhaps you’ve noticed – the days may be shortening, and the storms are doing doing their best, but autumn isn’t “autumning” quite as hard as she should be. While some trees are transitioning, many of their brethren are bare or still remarkably green, as if stuck in a summertime groundhog day. At Forestry England’s Westonbirt Arboretum, home to about 1,800 tree and woody shrub species, certain varieties are “certainly different to previous years”, says director Andrew Smith. The reason? Our beautiful trees, ill-adapted for this year’s extreme weather, are “stressed”. “We’re seeing a muted autumn because the trees have been under severe stress all summer,” says Kevin Martin, head of tree collections at Kew Gardens and an environmental scientist specialising in climate modelling and the resilience of urban and natural tree populations. “For the poor trees, they’ve gone from a spring drought into summer drought into an extensive heatwave . And this has caused the plants to be in distress.” Recommended How to help your body adjust after the clocks changed last night Why seasonal affective disorder will hit hard this year – and how you can fix it Forever-yellow bananas and vitamin-boosted tomatoes: gene-edited food is here The current drab showing of autumn colours is the result of a complex web of biochemical processes. open image in gallery At this time of year, many trees are usually displaying their autumn colours ( AFP/Getty ) Some species have experienced what’s known as a “ false autumn ”. “The trees were so stressed over the summer that their leaves have wilted and desiccated and then they’ve dropped them early – some of our trees were losing their leaves in August as a stress response,” says Charlotte Benham, science action and research manager at the Tree Council. That’s a “natural response to them trying to rebalance their transpiration load with the available moisture resources”, according to Smith: it’s a “survival strategy” in times of drought. Essentially, we’re not seeing the leaves changing colour now because those trees already shed them. In other cases, trees are doing the opposite and staying green for longer. Species like English oak, for example, are still growing when they’d normally be heading into dormancy. “They’re now starting to go into a bit of a growth spurt when they should be actually going into reverse and breaking those sugars down,” says Martin. Scientists have hypothesised that trees are doing this to make up for lost time and compensate for the dry summer, when their desiccated and discoloured leaves struggled to photosynthesise – the process by which they produce sugar and energy to store up and survive over winter – as much as they normally would. There are a lot of knock-on impacts to all these shifts that we don’t fully understand because everything is so interlinked Charlotte Benham, science action and research manager at the Tree Council “The best way I can explain it is that trees are like a battery,” says Martin. “They’ve got lots of stored carbohydrates, and they use those stored carbohydrates in times of need. When they’re really stressed, like this year, they fall back on this stored carbohydrate – so that’s why they’re still growing now, to try and get those reserves of carbohydrates back up.” The fabulous autumn colours we normally see are as a result of the breakdown of sugar and carbohydrates as the trees pull resources from their own leaves. But some trees’ leaves have gone straight from green to brown and then dropped off. In other instances, high winds from the first named storms of the season may end up tearing through the canopy and ripping off still-green leaves before they have a chance to change colour. This is far more problematic than merely denying us some pretty October visuals. “The trees won’t have had time to reabsorb the nutrients in the way they would have done if the leaves had changed colour and dropped off in the natural cycle of things,” says Benham. If the leaves fall while still green, they also have a slightly different nutritional and biochemical composition to a standard autumn leaf, which in turn affects their decomposition and how they influence soil health . “There are a lot of knock-on impacts to all these shifts that we don’t fully understand because everything is so interlinked, and the processes that lead to these organisms experiencing seasonal changes are so complex,” she adds. Trees, much like the rest of nature, are also just plain confused by all the mixed signals. Seasonal changes are in part triggered by changing daylight and weather. But, while day lengths are shortening, temperatures have remained unseasonably warm. open image in gallery The summer heatwave and extreme droughts put UK trees under stress ( PA ) “They don’t know whether it’s early spring or going into autumn,” explains Martin. “They’re now all confused and that’s also why we’re seeing this muted autumn, because they don’t quite know where they are within their yearly calendar.” Ripple effects of all this strangeness are predicted to continue into spring. Some trees have undergone “second flushes”, whereby they’ve dropped their original leaves and put out new ones. That means those buds are being used now, rather than in spring – which likely means they’ll have fewer leaves later in the year, forecasts Martin. “That will then affect the tree again going into next year’s growing season, because it’s not going to have as many leaves in order to photosynthesise and get carbohydrates,” he says. “We need to understand this constant stress and the effect it’s going to have on the trees over time.” It’s an active area of research, with precious little understood about what impact all of this complex interplay of factors will have on our trees and wider ecosystems over the longer term. What is clear is that Britain’s tree populations and landscapes will “certainly be different” over the next 50 to 100 years as the climate continues to change, says Smith. Native trees adapted for a moist, mild ecosystem, such as Beech trees, will struggle to survive as we move at pace towards a steppe semi-arid ecosystem similar to that of Romania or the Caucuses – defined by long, hot summers with very little rainfall; wet autumns and winters; and cold snaps in late winter into early spring. They’re now all confused and that’s also why we’re seeing this muted autumn, because they don’t quite know where they are within their yearly calendar Kevin Martin, head of tree collections at Kew Gardens Climate resilient planting is already being experimented with to help future-proof the UK’s trees; at Westonbirt Arboretum, they’re deliberately planting some species to test the edges of their survival. Making planting as structurally and genetically diverse as possible, meanwhile, has proven crucial for developing robust, healthy ecosystems. Aside from that, is there any way to “destress” our existing trees? Yes, according to Martin; it’s all about good horticultural management. Recommended How I changed my memory and intelligence scores in just four weeks Heidi Klum shares glimpse into her grotesque Halloween costume for 2026 Jenna Ortega says Disney Channel media training ruined her boundaries with fans “We need to think about how we can create more soil volume so we can hold more water for the plants,” he says. Mulching around the base of trees helps to hold in moisture; “if you can lock in that water that we predominantly get in December, January and February, if you can keep that within your soils, then that tree has that availability when it goes into growth in the spring,” he adds. “And that really helps them to then be able to deal with the droughts in the summer.” And one of the best things we can do to mitigate climate impacts is to plant more trees: if in doubt, plant a tree, as Benham puts it. “You have to be hopeful about these things, otherwise it’s very easy to get caught up in the doom and gloom of it all,” she concludes. “But nature is very resilient – if we give it the right kind of helping hand.”