UK upland regions contain extensive tracts of semi-natural heather dominated moorland.
These have a high conservation value for a range of protected species of flora and fauna.
A significant proportion of these heather-dominated regions provides evidence of anthropogenic change on a grand scale.
Although identified as having existed as far back as the Tertiary period, it is only during the Holocene that Calluna vulgaris-dominated heathlands became prominent (Stevenson & Birks, 1995). The origins of these semi-natural habitats can be dated back to the Neolithic period, c. 5500 BP arising from the early and continued impacts of forest clearance (fire) and the prevention of woodland regeneration by domestic grazing.
The following sections and the film on my media page describe the management of these heathland ecosystems on upland moorland lying above Lake Vyrnwy, in Mid Wales - -- between Lake Bala - Llyn Tegid and Lake Vyrnwy - Llyn Efyrnwy.
(O.S. Sheet 125, 1: 50000 : SH 985245).
These landscapes have been managed for hill farming and as a wildlife reserve by The Royal Society for the Protection of Birds since 1977. Owned by Severn Trent Water Authority, RSPB management commitments vary but at the time of writing extend to some 4,452 ha of surrounding farmland and 6,475 ha of adjoining forest and upland moorland.
Common heather, Calluna vulgaris is the dominant plant species, and provides both cover and nutrition for ground nesting moorland birds and associated vertebrate and invertebrate organisms comprising the food web of this upland ecosystem.
Changes in the floristic composition of upland heather moorland in the UK overall are matters of concern. In the sub-montane regions of mid-Wales this issue is of particular importance as these landscapes are vulnerable to species change due to a number of environmental factors and require management for their continued existence.
As heather plants age gaps occur in the degenerate stands and these are often colonised by shrubs, trees and other potentially persistent dominants such as, the grasses wavy hair grass Deschampsia flexuosa, purple moor grass Molinia caerulea and the matt grass Nardus stricta. In this condition senescent stands of Calluna vulgaris are at risk from successional replacement by acidophilous grasses and moorland sedges, ultimately resulting in floristically less diverse plant communities and a progressive transformation into rough grassland or moorland scrub.
Senescent degenerate stands of heather :
Traditionally , burning has been used to maintain Calluna dominance by the removal of senescent stands of the plant in its degenerate phase and promote the regeneration of young shoots from seed and by vegetative growth.
More recently, burning has been reduced and mowing (cutting) and controlled grazing by hill sheep and ponies are used to achieve these same ends. However, environmental factors such as soil nutrient status and the soil mechanical properties promoted by different types of management can influence florisitc composition.
(click on map images to enlarge management maps by cutting :
location and chronosequence detail)
