Module 6 Nitrogen pollution and heather moorlands

Is nitrogen pollution contributing to the decline of our heather moorlands?
Heather (Calluna vulgaris) occurs throughout Europe, although it is less common in Mediterranean countries. In the north of its range (eg Scandinavia and the uplands of Scotland) it is a dominant species that occupies large tracts of uplands. Heather dominated uplands are visually attractive, especially in the late summer and the early autumn when heather is in flower. Some heather moorlands occur within National Parks, Environmentally Sensitive Areas and Areas of Outstanding Natural Beauty, and some are managed for grouse shooting. Heather is an ecologically interesting species in its own right, but it is also provides an important habitat for wildlife, such as the grouse and its predator the merlin (Falco columbaris).   The grouse depend on heather as a source of food and cover.

During the last decade there has been a steady decline in the size and health of UK heather moorlands. Some of the decline is directly attributable to management practices such as increased forestry, agricultural encroachment, or lack of management. Neglected heather moorland reverts to scrub. Healthy heather moorland can only be sustained by burning, or controlled sheep grazing. There are also growing concerns that heather moorlands are declining because of environmental pollution, particularly from nitrogen. A number of recent studies have shown a clear relationship between nitrogen concentrations in heather leaves and nitrogen deposition from the atmosphere.

The aim of the CS2000 heather study is to:

• Establish whether there are regional patterns of nitrogen concentrations in heather leaves.

• Compare such regional patterns of nitrogen concentrations in heather leaves with regional patterns of UK atmospheric nitrogen deposition.

• Assess whether nitrogen concentrations in heather leaves can be used to identify areas of the UK where excess nitrogen deposition is likely to trigger a decline in the heather communities.

For more news on heather sample analyses see newsletter issue 4, page 2.