Conservation of Calluno-Vaccinietum heathland in the Belgian Ardennes, an experimental approach.

  • Published source details Froment A. (1981) Conservation of Calluno-Vaccinietum heathland in the Belgian Ardennes, an experimental approach.. Vegetatio (now Plant Ecology), 193-200.


Large areas of heather Calluna vulgaris-dominated heathlands in Western Europe have been lost to development and agriculture, and many remaining heaths have rapidly succeeded to successional pressures (become dominated by shrubs and trees) because the traditional management such as agro-pastoral practices and periodic fires which were responsible for their formation and maintenance, have been abandoned.

The Hautes Fagnes is a plateau area (highest point 694 m a.s.l.) in northeast Belgium, consisting of about 5,000 ha of remnant open areas ('fagnes') remaining after extensive establishment of Norway spruce Picea abies plantations. Most of the fagnes comprise bogs, wet heath, semi-natural grassland and heathland, and lie within the Hautes Fagnes nature reserve. In addition to management by mowing and sheep grazing, in the 1800's there was occasional 'burn-beating' (écobuage) cultivation - sods were cut, dried and burnt, and the ashes were spread over the soil as fertilizer for a rye crop sown after preparing the field by creating ridges. Today, the resultant 'ridged heathland' is very much like the dry heathland in the area (covered with Calluna and Vaccinium spp.), and is rich in bilberry Vaccinium myrtillus and bog bilberry V.uliginosum, whilst in the furrows there are more grasses such as purple moor-grass Molinia caerulea, wavy hair-grass Desehampsia flexuosa with various wet-heath plants.

Study area: The experiments were undertaken in Hautes Fagnes nature reserve in the province of Liège, Belgium.

Plots and treatments: Four experimental plots were set up in 1972 in an area of ridged heathland and the following management treatments were applied:

plot A (150 m²) - mowing and litter left;

plot B (150 m²) - mowing and litter removed;

plot C (500 m²) - burning;

plot D (250 m²) - burn-beating.

Vegetation monitoring: Vegetation in the experimental area was mapped beforehand, and again in 1980. Permanent quadrats were set up in each plot to follow the development of the vegetation.

Burn-beating: Burn-beating removed the humus layer almost entirely, vegetation developed very differently to other treatments and vegetation changes were marked. In 1972, most of the plot was occupied by a mix of V.myrtillus and V. uliginosum with some C.vulgaris and M.caerulea. In 1980, the vegetation was characterized by Calluna and the moss Polytrichum commune, which both covered large areas. The first year after burn-beating, vegetation cover was about 50% (range 20-70%). Heath rush Juncus squarrosus and soft rush J.effusus became abundant during the first years, and numerous C.vulgaris seedlings were observed.

The two quadrats established in the area were placed in slightly different habitats: quadrat 1 on drier ground, and quadrat 2 on wetter ground. The differentiation in vegetation between them was noticeable. In 1980, quadrat 1 was dominated by C.vulgaris and common broom Sarothamnus scoparius (Syn: Cytisus scoparius) with some heath woodrush Luzula multiflora congesta; quadrat 2 was dominated by P.commune, which became apparent in 1976 and mostly replaced the grasses (M.caerulea and D.flexuosa) as well as cross-leaved heath Erica tetralix and Sphagnum fimbriatum, which were predominant in 1978.

Burnt area: M.caerulea and D.flexuosa became more dominant as V.myrtillus and V.uliginosum patches regressed. Small patches of velvet bent-grass Agrostis canina and purple small-reed Calamagrostis canescens increased in size, whilst C.vulgaris formed a few small isolated patches; large white-moss Leucobryum glaucum almost completely disappeared after burning. In consequence by 1980, a more open mosaic than before the burning had developed.

Mown areas: The mown areas with litter left or removed, developed in much the same way as the burnt area, however, expansion of grasses was less.

Conclusions: In this study, mowing and burning led to a regression of the desired ericaceous shrub species which are characteristic of these heathlands, with replacement by common grasses such as D.flexuosa and M.caerulea. Burn-beating produced far better long term results in terms of acheiving target plant communities and also made the heathland more resilient to invasion by trees thorough removal of the nutrient-rich humus.

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