Slow recovery of heather (Calluna vulgaris L. (Hull)) in Scottish moorland after easing of heavy grazing pressure from red deer (Cervus elaphus L.)

Summary

The study aimed to determine how quickly heather responds in Scottish moorland once deer grazing pressure is reduced. We monitored heather attributes and deer distribution over ten years in Glen Lui and Glen Derry, two contrasting nearby areas of it 200 ha at Mar Lodge in the eastern Cairngorms. In one area the deer received winter food, affecting the zonation of their impact. In both areas the deer were initially lightly culled, then culling was increased.

Mean heather shoot utilisation was 35 % and 48 % less in the last five years of the study than initially in the two areas, and was very closely correlated with deer pellet-group counts. In Glen Lui heather cover increased significantly but height increases were small. In Glen Derry heather increased significantly in height but little in cover. We attributed the different response to the presence of a secondary grazer (rabbits, Oryctolagus cuniculus) in Glen Lui and also better conditions for heather growth on the drier soils there; rabbits grazemore delicately than deer, taking mainly the shoottips of heather and thus encourage lateral shootgrowth. In Glen Lui heather response also varied between four radial zones based on distance from the feeding grounds. At best, there was appreciable recovery four years after the easing of deer grazing pressure, but average amounts of recovery were modest.

Key words:

• grazing impact
• heather moorland
• red deer
• supplementary feeding
• utilisation