The National Trust is warning that one of the best loved sights of autumn, the changing colour of tree leaves, will be heavily impacted by the warming climate unless urgent action is taken to tackle climate change.
With this year’s record-breaking temperatures, prolonged periods of hot, dry weather over the summer months and many areas experiencing drought conditions, trees all around the country are being put under immense stress and some are struggling to survive.
Signs of this have been seen across the UK with many thinking autumn had arrived early with brown leaves carpeting the ground in August – but this phenomenon, known as a ‘false’ autumn, was due to the drought and trees simply not having enough water.
Pamela Smith, senior national gardens and parks consultant at the National Trust said: “Due to the leaf drop that has already occurred in isolated areas this year’s autumn colour will be reduced due to the simple reason that many trees have already lost a lot of their leaves due to the hot summer.
“Trees suffering due to drought don’t have the resources to sustain their size, so often the impact is a smaller leaf canopy.
“However, in terms of the typical autumn cycle, it remains to be seen what the drought and high temperatures could mean for this year’s autumn colour, but we may see more golden browns and yellows as a result – and this year could be quite a unique display.
“Biologically, long daylight hours are needed as well as the right mix of sunlight and rain – and hopefully trees were able to build up plenty of sugars in the spring and early summer so that the high temperatures had little impact – and it will only be those trees already under stress that will be impacted.
“It’s likely that well established trees will be more resilient and that we will still see the full colour spectrum, but this year is a warning to us all of how what we’ve previously taken for granted, may be at risk.”
DID YOU KNOW: Autumn colour is determined by both what the weather is doing now, but also the weather patterns across the year. While good levels of sunshine, but also rainfall is needed to build up sugars in the leaves, a lack of rain causes stress for the trees with potentially early shows of yellow or brown autumn colour and leaf fall. Autumn colour also typically only starts to show once temperatures start to get cooler overnight – but remaining above freezing.
The shortening of the days and lower light levels in October stops the production of chlorophyl, the green energy creating pigment in leaves.
As the green pigment fades (due to the trees withdrawing sugars from the leaves) the underlying colours of reds, oranges, browns and yellows become apparent.