Tree planting without fences aims to boost biodiversity

A different approach to tree-planting is being trialled by Scottish Natural Heritage (SNH).

In areas with deer, it is normal for trees to be planted with fencing to protect rarer native saplings. But under a technique being trialled at Creag Meagaidh and Beinn Eighe National Nature Reserves, managed by SNH, trees will be planted without fences.

Methods will be trialled to establish tree species which struggle to gain a foothold due to deer browsing. Some species have died out in areas due to the presence of deer, and are unlikely to naturally recolonise as a result of a lack of seeds.

Fencing is expensive and can cause negative impacts on access, landscape and biodiversity.

The tree planting techniques at the two reserves are:

• Planting tall saplings on steep slopes, or inaccessible areas in which the leading shoot is out of reach of deer (sabre planting);

• Hiding rarer species in the landscape, making them less visible and accessible to deer;

• Covering the leading shoot with ‘budcaps’ – used in Germany and the USA;

• Using harmless chemical repellents to make the tree unpalatable.

Chris Donald, SNH’s South Highland operations manager, said: “Heavy grazing by deer causes stunted trees which fail to grow above surrounding vegetation. If we can find techniques for establishing these species without costly and unsightly fences, it will help woodland managers create greater diversity.

“We are committed to trialling these techniques to see if they can be used on a wider scale – especially where deer densities are low and surrounding habitats are in good condition. National Nature Reserves are ideal locations to undertake this kind of novel management.

“‘Natural’ protection’ uses thickets of other species – such as birch, whins or bracken – less attractive to deer and hides rarer species to let them flourish. I have seen this recently in the New Forest National Park where well developed birch and gorse thickets harboured aspen despite high numbers of deer and forest ponies.”

Other ‘protection’ species in Scotland include whins; blackthorn; hawthorn; dog rose; holly; juniper; broom; bramble, and bracken.