PESTS and diseases are set to spread through Scotland's forests as a result of climate change, with potentially devastating impacts, a report has warned.
Diseases likely to take greater hold in the trees in Scotland's woodlands include a needle blight that attacks about 60 species of pine. In order to tackle it, Forestry Commission Scotland (FCS) has banned planting of Corsican pine, and has warne
d a moratorium might be needed on other species.
And a moth called the horse chestnut leaf miner is likely to arrive in Scotland with the warming temperature, experts believe. It makes horse chestnuts' leaves wither.
Outbreaks of bleeding cankers, green spruce aphid and pine weevils are also likely to increase as the climate warms, the report from FCS warns.
Roddie Burgess, head of plant health at FCS, said staff were carrying out research into the likely impact of climate change. "What's very clear is that it will have an impact," he said.
"Just how serious it will be, we don't think we can say with any certainty yet, but it's giving us considerable cause for concern."
Red band needle blight was first spotted in the UK in the 1950s but has only become a serious problem recently.
"In the last few years, it really has developed into a full-blown disaster," said Mr Burgess. "It's probably the biggest issue facing commercial forests today."
The disease – recognisable by a distinctive red band around each needle – can kill trees, affect their rate of growth and reduce the quality of their timber.
It thrives on Corsican pine, but has also attacked Lodgepole pine and Scots pine.
The threat is so serious that there may have to be a ban on planting these pine species in the future, with other types of tree grown instead, such as birch or other conifers.
"We are looking at alternative species we can use instead of pine," Mr Burgess said.
In East Anglia, eucalyptus is now commonly planted instead of pine, because of red band needle blight.
Horse chestnut leaf miner, a moth that was first spotted in the UK in 2002 in Wimbledon, has spread gradually north and has got as far as Yorkshire.
"With climate change, I think it will continue to march north," said Mr Burgess.
The larvae bury themselves into leaves, turning them orange as though it was autumn.There is no known cure.
"The best we can do is sweep up the leaves and burn them," said Mr Burgess.
Also predicted to increase with climate change is the number of forest fires.
Mr Burgess said: "It's a simple fact that the more trees that get killed by pests, the more readily flammable material there is. A living tree doesn't burn very well."
Actions to try to help prevent the spread of the pests and diseases are outlined in the FCS report, Climate Change Action Plan 2009-2011.
They include carrying out further research and avoiding the introduction of new or vulnerable species.
Red band needle blight:A fungal disease that affects conifers all over the world. The disease is caused by a fungus and causes a distinctive red band around pine needles.
Horse chestnut leaf miner:A moth discovered in Macedonia in the 1970s. Its larvae burrow into the common horse-chestnut, turning the leaves brown and stunting growth.
Phytophthora ramorum and phytophthora kernoviae: These pathogens cause Sudden Oak Death, which killed thousands of oaks in California. In the UK it has mainly affected rhododendrons and blaeberry. There are fears it could spread faster in warmer, wetter conditions, and attack other tree species, as well as Scotland's iconic heather.
Bleeding canker of horse chestnut: Pseudomonas syringae pv aesculi is also believed to spread faster in warm weather. Originally from the Himalayas, a study in Britain showed symptoms in almost half of trees tested. There is no known cure.
Forest fires: As more trees die, there will be more litter on the ground that can easily catch fire.
Invasive species: There are fears a warmer climate could cause alien species that currently do not cause a problem to become invasive.
