Woodland regeneration increases by 25% at Highlands National Nature Reserve

21 December 2023

Naturally regenerating trees have increased by around 25% in six years at Invereshie and Inshriach National Nature Reserve (NNR), a new survey shows.

This year NatureScot commissioned a repeat of a 2017 survey that looked at tree regeneration over 1,025 hectares of land at Inshriach, near Aviemore.

The survey focused on open areas next to the existing established woodlands, as the aim was to see if the woodland is expanding. It covered land stretching right up to an altitude of 900 metres.

The survey, funded by the Endangered Landscapes and Seascapes Programme through the Cairngorms Connect Partnership, found that the density of all tree species in the area increased by around 25% over the period as new seedlings and saplings established.

Scots pine increased from 281 to 313 stems per hectare, juniper increased from 56 to 102 stems per hectare and birch from two to 10 stems per hectare. The species of new seedlings and saplings are strongly influenced by the existing adult trees and therefore the available seed source for natural regeneration.

With no planting or deer fences on the NNR, all of the woodland expansion has taken place through natural regeneration aided by deer management undertaken by Cairngorms Connect deer stalkers.

Habitat Impact Assessments, which measure the impact of deer and other herbivores on habitats, were also carried out, with grazing found to be having either no or low impact on most plots.

The findings build on recent research published by Cairngorms Connect showing how long-term coordinated deer control, with minimal need for fencing or planting, can enable trees to recolonise upland areas at a landscape scale.

Ian Sargent, NatureScot’s reserve manager for Invereshie and Inshriach NNR, said: “With our partners in Forestry and Land Scotland and the wider Cairngorms Connect Partnership, we’ve been managing deer impacts on the NNR for more than 50 years, with an emphasis on encouraging natural regeneration.

“With this survey, it is really heartening to see the progress that has been made in the last six years alone. The ancient native pinewoods are continuing to expand, with regeneration sometimes recorded more than 1km from the nearest mature established woodland. Juniper and birch are also doing well on the reserve.

“Our aim is to allow the woodland to function naturally and to re-colonise high altitude areas, so it’s great to see regeneration is already occurring well above 600m and in some cases even on the very exposed summits of some of the peaks.”

NatureScot Chief Executive Francesca Osowska said: “The results we are seeing at Invereshie and Inshriach National Nature Reserve and in the wider Cairngorms Connect area are a great example of what can be achieved working in partnership to achieve woodland recovery and expansion on a landscape-scale.

“Globally and in Scotland, nature is in decline and we face a climate emergency. Deer are an iconic part of our biodiversity but in high numbers they can have a negative impact on woodland and other habitats. The sustainable management of Scotland’s deer, such as is happening at Invereshie and Inshriach and elsewhere, is vital if we are to meet ambitious and necessary targets to restore nature and reach net zero.”

New surveys were also carried out this year on the Invereshie part of the NNR and at Beinn Eighe NNR, which will establish a baseline for comparisons to be made at these sites in future.