Warnings autumn could be at risk due to climate change 

Published:
5:30 AM September 29, 2022

Each year, their kaleidoscopic colours create one of nature’s greatest displays.

But the golden hues of autumn leaves could become a thing of the past, the National Trust has warned.

It says the season’s changing colours could be at risk because of climate change, due to the huge stress that prolonged periods of hot, dry weather have on trees.

While some leaves are dropped early, others are scorched by extreme temperatures and do not display the usual bright reds, oranges and yellows.

Officials say they are still waiting to find out how much impact the summer’s heatwave has had at its Norfolk sites.

They have warned that the record-breaking temperatures and drought conditions have put immense stress on trees across the country, with some struggling to survive.

In Norfolk, this has already been witnessed at some of its most adored landmarks.

Dea Fischer, senior gardener at Oxburgh Hall, near Swaffham, said: “The extreme heat this summer was hard for our gardens. The stream that runs through them had largely dried up and the grass was very parched.

“Maintaining our gardens throughout the heatwave was hard work and it’s thanks to the dedication of the team that a large majority of our plants pulled through. It will however likely take a lot more time before the grass and the water levels in the stream recover.”

The hall’s area ranger, Tom Day, added: “It is undeniable that the high temperatures and prolonged absence of rain have left a substantial mark throughout the parkland, which will be especially prominent now as we are approaching autumn.

“Many trees dropped large quantities of their leaves during the heatwave to prevent water loss and direct any available water to core functions.

“As a result of this accelerated leaf drop, some trees like the horse chestnut are already completely bare.

“At the same time, leaves of other trees, particularly sycamores, were scorched by the extreme heat and have turned brown or even black and will not show the usual bright reds, oranges and yellows we have come to expect.

“This summer has shown that we may need to prepare for a new reality for our trees.  

“If temperatures continue to rise, the combination of hotter summers, a lack of cold snapbacks and new wounds will inevitably lead to an increase in diseases like ash dieback, oak decline and honey fungus.”

Many would be forgiven for thinking that autumn had arrived early with brown leaves carpeting the ground in August.

This phenomenon, known as a ‘false autumn’, was due to the drought and trees simply not having enough water.

There have, however, also been some unexpected and positive benefits, Ms Fischer explained. 

“Our orchard, where we grow our apples and pears, is having the most phenomenal year and the trees are practically overflowing with fruit,” she added. “This stands in a stark contrast to the poor harvest last year, caused by a very wet summer. 

“There is an uncommonly big crop of raspberries, and our hedgerow plants such as hawthorn and blackberry bushes are absolutely packed with berries.

 

“We’re hoping for a stunning display from our Four Seasons Border where maple, cherry, and crab apple trees were deliberately planted with their spectacular colours in mind, and which have all survived the heatwave mostly unscathed.” 

Autumn colour typically only starts to show once temperatures start to get cooler overnight – but remaining above freezing. 

The colours are determined by both what the weather is doing now, but also the weather patterns across the year.

Good levels of sunshine and rainfall are 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.

• To help more people to get outdoors to experience all elements of autumn, the National Trust is offering the public an opportunity to visit a National Trust property for free.  For more information visit www.nationaltrust.org.uk/escape-into-autumn 
• The National Trust introduced an ambition plan to plant and establish 20 million trees by 2030.  To make a donation, visit www.nationaltrust.org.uk/plant-a-tree