Exotic trees putting Caledonian pine at risk says new study by scientists

SCIENTISTS are calling for some non indigenous trees to be removed from forests in Scotland and potentially banned from being planted at all to help save under threat native species.

They warn exotic pine tree species planted next to native Scots Pine forests increase the risk of disease to native trees,ccording to a new study.

And they say remedial action has to be taken to preserve the Caledonian forest family.

Experts from Scotland’s Rural College and the University of Edinburgh carried out an in-depth study to show how increased numbers of Corsican Pine from Europe and Lodgepole Pine from North America are heightening the risk of disease when planted next to native Scottish Pine species.

The SRUC’s Peter Hoebe, a plant researcher, and Honorary Fellow Richard Ennos from university of Edinburgh say the widespread planting of exotic species in dense forests has introduced new races of fungi and raised the threat posed to native Scots pine.

They studied genes in fungi attacking pine needles from a number of locations, including forests around Aviemore.

The research was to determine the diversity and spread of the fungus Dothistroma septosporum.

This disease is responsible for the current outbreak of Dothistroma needle blight (DNB) in native Caledonian Scots pine populations, as well as other species.

They claim to have discovered that the widespread planting of Corsican Pine and Lodgepole Pine placed native species at greater risk of disease.

And they  said that the removal of exotic species from the vicinity of Caledonian pine populations and the restriction of movement of planting material was now necessary to minimise its impact.

Dr Hoebe said: “This extensive study involved collecting hundreds of needles from forests around Scotland.

“In many cases, needle blight itself doesn’t necessarily kill the trees, but the loss of needles affects the growth of mainly young pines.

“While introducing exotic species to Scotland can sound very appealing, there are distinct risks involved. Planting exotic species related to native species reduces rather than enhances the resilience of forests to pathogens.”

Prof Ennos added: “Our extensive study sheds new light on the risks associated with the introduction of exotic species in general, and valuable insight into how the current needle blight outbreak might be better managed.”

The project was funded jointly by a grant from BBSRC, Defra, ESRC, the Forestry Commission, NERC and the Scottish Government, PROTREE, under the Tree Health and Plant Biosecurity Initiative.

WANT TO LEARN MORE? Read: Planting exotic relatives has increased the threat posed by Dothistroma septosporumto the Caledonian pine populations of Scotland


Shaun Milne is a Scottish based journalist with a particular interest in environmental issues, politics and travel.

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