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Balancing Hill Sheep Production With Environmental Gain – The Acid Grassland Project
Published: Mon, 05 Sep 2005
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Research Note Full Title
Balancing hill sheep production with environmental gain – the Acid Grassland Project
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CAP reform is likely to result in changes in hill sheep numbers. It is hoped that these changes will lead to an increase in biodiversity. Recent work by SAC has shown that hill grasslands with high levels of Nardus stricta show little change in plant species composition even after a halving of the grazing pressure. Research points to sward structure as the driver influencing the number of invertebrate species and upland birds. Although changes in sward structure are more easily achieved than changes in species composition and may be the key to environmental gain, this approach may not be suitable for the sheep themselves. More tussocky grassland is considered less productive for sheep.
Objectives
- To create structurally diverse swards through modified grazing management at the full system scale in contrasting grasslands.
- To study impacts on the structure at the individual plant, patch and system scales, and to see how sward structure influences animal behaviour and performance, and through linked studies, influences invertebrate diversity and productivity.
- To produce guidelines for managing upland grasslands for both biodiversity and sheep production.
Approach
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Two Contrasting Study Sites:
- SAC Kirkton Farm in West Perthshire (two ~40ha systems) – intimate mixes of vegetation communities with indistinct Nardus tussocks
- Macaulay Institute’s Farm at Sourhope in the Borders (two ~60ha systems) – large discrete patches of different communities with very prominent Nardus tussocks
Grazing Management:
- Sheep grazed all-year-round
- Sheep grazed from June to October (‘summer-only’ grazing)
- No grazing (small exclosures)
Vegetation Types Being Studied:
- Nardus stricta - Galium saxatile ‘tussock’ grasslands (U5, U5c & U5b)
- Festuca ovina - Agrostis capillaris ‘smooth’ grasslands (U4)
Methods:
- Sward stick measurements and point quadrats used to determine structure and species composition.
- Digitised tussock maps used to study the size, number and distribution of Nardus tussocks
- GPS collars used to determine how different sward structures might lead to differences in foraging behaviour.
- Inter-related mapping and analysis using GIS at the system scale (see figure to right).