Feeding blocks can influence the grazing behaviour of sheep by encouraging them to concentrate their grazing activities within restricted areas of moorland; however, if they are placed on vulnerable areas (e.g. heather-grass interfaces), such concentration can cause considerable damage to underlying vegetation due to over-grazing and trampling. This study will use feeding blocks to draw sheep away from areas where Calluna is vulnerable, thus increasing establishment of Calluna in sensitive areas such as heather-grass interfaces. Impact of feeding block placement on composition and rates of vegetation change in areas where Calluna is lacking (e.g. in Nardus-dominated areas), rank or over-mature will also be studied.
The project is composed of 6 specific objectives, these are listed below together with a summary of how they will be achieved:
1. Effectiveness of feeding blocks in drawing sheep away from, and reducing grazing pressure on, vulnerable areas is assessed from grazing patterns, as well as from grazing levels and rate of Calluna/Nardus replacement at heather-grass interfaces, for each paddock pre- and post-treatment;
2. Effect of feeding block density on vegetation structure and rate of species replacement around each block is determined by comparison of the magnitude of changes observed on each of the treatment areas;
3. Effect of season (spring/autumn), during which feeding blocks are installed, on vegetation structure around each feeding block; to be evaluated by comparison of the magnitude of structural change measured following March/April and Sept/Oct treatment periods. Seasonal effects of feeding block installation on plant species change will also be determined by comparison of species replacement, with reference to 4 vegetation types, Calluna-dominated, Calluna/Nardus interface, Nardus-dominated (no feeding blocks present) and Nardus-dominated (feeding blocks present);
4. Effect of feeding block treatments on large-scale grazing patterns will be evaluated by comparison of pre- and post-treatment grazing assessments taken across the whole paddock. Influence of feeding block treatments on large-scale species balance across the whole paddock will also be derived from information on rate of species replacement to the whole paddock;
5. The relationship between grazing level, heather growth and change in Calluna/Nardus cover will be explored using linear and non-linear regression analysis; this uses grazing level as the independent variable and rate of species change as the dependent variable, with fixed factors being treatment and initial species dominance (where appropriate);
6. Economic/practical considerations surrounding use of the most successful treatment density of feeding blocks to manipulate grazing levels are examined in relation to cost of the blocks, labour required and rate of vegetation change observed.