Montane Scrub

Natural Heritage Management

• Foreword
• Introduction
• What is montane scrub
• The loss of the ‘wee trees’
• Plants of the scrub
• Wildlife in the scrub
• Restoring the landscape
• The woods and the trees
• Shelter on the hill
• Game benefits
• Enjoying the hills
• Ecological values
• Action for scrub
• Bringing back the ‘wee trees’
• Further reading

Ecological values

In the relatively extreme situation of high altitudes, montane scrub can have a valuable protection role. By establishing greater shelter and deeper, more robust root systems, it helps to prevent erosion, especially on hillsides which have suffered from heavy grazing in the past. It can also reduce leaching (the process by which rain washes minerals and nutrients deep down into the soil or into streams, so that surface soils become progressively more impoverished). The roots of the shrubs draw goodness from the soil and return it to the soil surface in their leaf litter, helping to maintain the natural nutrient capital of the soil.

The humid substrate established beneath the scrub canopy absorbs rainfall during wet periods, thus contributing to reduced run-off and lessening the risk of flooding downstream. It then releases this water gradually, helping to maintain river flows and reduce the likelihood of drought in dry conditions. The leaf litter beneath the scrub might slow the release of atmospheric pollution into burns, to the benefit of sensitive vegetation downstream.

Perhaps most importantly, as this booklet has shown, montane scrub represents a natural zone of transition between woodland in the straths and montane heaths higher on the hill.

At the 'Earth Summit' in Rio de Janeiro in 1992, Britain signed the Convention on Biological Diversity. Biological diversity - or 'biodiversity' for short - is defined as "the total diversity and variability of living things, and of the systems of which they are part". The principles of biodiversity therefore require the protection of natural habitats and processes, as well as species. The restoration of montane scrub is thus a vital part of the reinstatement of natural patterns and processes in the Scottish hills.

The Cairn Gorm ‘Krummholz’

In the Northern Corries of Cairn Gorm, a substantial colonisation of low, twisted pines, with occasional juniper, rowan and birch bushes, has developed at an altitude of between 450 and 850 metres. This seems to have begun following the cessation of burning and very substantial deer culls in the area in the mid-1940s. The fencing of large areas of lower ground for forestry has greatly reduced the use of the Northern Corries by deer, and the increase in human activity following the ski developments at Coire Cas also discourages deer, especially during winter when the scrub is most likely to be grazed. If browsing pressure remains low, this may lead eventually to the establishment of montane pine scrub, but the other scrub species will remain depleted, at least for the next century or so, unless there is active intervention to aid their spread.