Ash dieback disease plaguing forests could be stopped by hedgerows and may NOT be as harmful as previously thought, study finds
- Study assessed levels of the fungal disease in a 22 square km patch of woodland
- Found that within two years the disease was found on almost all trees in the area
- However, trees in isolated areas were hardly effected by the ash dieback fungus
- It is though sunlight and temperatures above 30°C helps subdue the disease
Ash dieback, the fungal infection plaguing British forests, may not be as devastating as previously believed, a study claims.
Scientists studying the progression of the disease in northern France found it is far less severe in isolated landscapes, such as in hedgerows.
They say that while the disease can spread to all ash trees in a certain area, the severity is often mild.
Previous predictions have forecast imminent doom for ash trees caused by the disease, speculating that only five per cent of trees would survive an outbreak.
However, the French researchers believe it is more likely that 80-95 per cent will remain healthy, despite low levels of infection.
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Scientists studying the progression of the disease in northern France found it is far less severe in the isolated landscapes such as in hedgerows. Ash dieback causes black blotches on leaves and lens-shaped lesions on stems (stock)
Scientists from the British Ecological Society found some commonly found environments help stave off high levels of infection.
A 22 square kilometre patch of woodland in north-east France was first assessed for the fungus in 2010. The first record of the disease in the UK was in 2012.
Regular assessment of the spread of the fungus revealed it ‘had spread to virtually all ash trees present in the studied landscape within two years’.
However, many areas saw the trees growing healthily, seemingly uninfected by the infection.
Checks on the trees in both 2016 and 2018 revealed the afflicted regions remained largely healthy, despite signs of infection.
Researchers found that after ten years, the disease remained mild in many places.
‘We found that the disease had spread to virtually all ash present in the studied landscape within two years. Nevertheless, in many areas ash trees remained relatively healthy’ said lead author of the study Dr Benoit Marçais, French National Institute for Agriculture, Food, and Environment (INRAE).
‘The view that only the most resistant part of the ash population, just a few percent of the individuals, will survive the ash dieback pandemic is wrong.
‘We see that in many environments not favourable to ash dieback, the proportion of ash that remain healthy is closer to 80-95 per cent than to five per cent, although the disease may be locally very severe.’
It is thought the isolated trees are relatively unharmed by the disease due to a combination of factors.
The distance between trees helped limit transmission but the isolated trees or those in open canopies had higher temperatures at their crown — at its highest point.
Previous predictions have forecast imminent doom for ash trees, speculating that only five per cent of affected trees would survive an outbreak. However, the French researchers believe it is more likely that 80-95 per cent will remain healthy, despite infection (stock)
This, the researchers write in their study, published in the Journal of Ecology, is less favourable for the development of the pathogen that causes ash dieback, Hymenoscyphus fraxineus.
High summer temperatures brought on by global warming will likely see this trend continue and the pathogen suppressed even further.
Climate change predictions state peak temperatures in northern France could reach as high as 35°C, at which point the virus can not survive.
The researchers warn that their study only holds true for the north-west France, and further research will be needed to assess if the same trend is seen in different climates, such as in the UK.