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Vegetation change and Calluna-Nardus interaction in relation to spatial variation in grazing pressure on moor(old BD0115 - BD1211

This study will investigate the long-term effects of Cambrian Mountains ESA grazing programmes (and other reduced stocking rate procedures) on vegetation change; impact of spatial variation in grazing pressure on vegetation change is also considered. A spatial model of vegetation change is under development in order to examine the importance of variation in sheep grazing patterns in relation to rate of vegetation change within degraded moorland plant communities. The study will focus on interactions between the 2 dwarf shrub species that predominate in the area (Calluna vulgaris and Vaccinium myrtillus) and a strongly competitive grass species (Nardus stricta).

The project is composed of 7 specific objectives which are listed below together with a summary of how they will be achieved:
1. Quantification of effects of ESA grazing prescriptions on degraded heather and grass-dominated moorland plants. Rate and direction of plant community change are investigated by routine vegetation sampling of plots on a 2-yearly basis, which ensure that long-term (i.e. 10 year) effects of ESA programmes may be observed;
2. Evaluation of the seedbank on grass-dominated, previously over-grazed moorland areas, to determine the viability of re-establishing Calluna moorland – this technique would avoid seed application. Soil samples are taken from permanent quadrats and the seeds collected are germinated under controlled conditions before the seedlings produced are identified;
3. Development of field trials to assess effects of sheep grazing pressure on different grass species, especially Nardus. Approaches may include quantification of number of blades grazed, biomass/length of blade lost, annual growth increment within grazed and ungrazed blades and assessment of structural characters;
4. Examination of the spatial pattern of grazing in relation to vegetation composition on grass-dominated and heather-grass moorland. Information on balance of key species (e.g. Calluna, Vaccinium and Nardus) across the same areas will also be collected, while sampling will measure seasonal and annual variation in spatial pattern of grazing pressure;
5. Examination of the relationship between rates of vegetation change (particularly in relating to balance of Calluna, Vaccinium and Nardus) and grazing pressure at the quadrat scale;
6. Assessment of spatial variation in vegetation occurrence using a cellular automata model, which is based on species replacement data obtained from permanent quadrats. The information is used to establish replacement “rules” for species transition within degraded moorland plant communities under known levels of grazing pressure. The model will be applied to assess impact of variation in grazing pressure on vegetation and will be tested against field data;
7. Identification of appropriate grazing scenarios to enhance vegetation recovery and Calluna regeneration on degraded moorland.
Project Documents
• Final Report : Assessment of vegetation change and Calluna/Nardus interactions in relation to spatial variation in grazing pressure on upland moor.   (1238k)
Time-Scale and Cost
From: 1998

To: 2002

Cost: £283,176
Contractor / Funded Organisations
Agricultural Land              
Environmental Protection              
Fields of Study
Environmental Stewardship