Coastal grazing marsh - effect of increasing stock levels

As stock levels increase and the grazing period extended, the structure of the vegetation is reduced. Plant species diversity and the associated invertebrate fauna is correspondingly reduced also. The less structurally diverse sward has fewer sites suitable for ground-nesting birds and hence their numbers and decrease. Other factors also come into play:

• The increase in stock levels is often accompanied by lowering water tables by drainage, which has an influence, notably on wintering birds, though it can also contribute to the reduction in breeding success;
• The use of artificial fertiliser will increase early season grass growth, but at the expense of breeding waders that prefer short swards, botanical and invertebrate interests;
• Increased stock densities also lead to a reduction in species diversity and an increase in the destruction of the nests of breeding birds.