The relative importance of grazing stock type and grazing intensity for conservation of mesotrophic 'old meadow' pasture

Reduce grazing intensity on grassland (including seasonal removal of livestock)

A 2008 systematic review (Stewart & Pullin 2008) identified several studies that suggest that intermediate grazing levels on neutral grassland (MG5 crested dog’s-tail Cynosurus cristata-lesser knapweed Centaurea nigra grassland under the UK National Vegetation Classification) benefit plants, invertebrates or birds, but noted that trade-offs probably exist between the grazing requirements of different taxa. Four studies suggested that intermediate grazing levels are most appropriate for plant conservation objectives. Where grazing levels are very low, or grazing is abandoned, ecological succession leads to a reduction in the number of plant species. High grazing intensity also reduces plant species richness, because a limited number of competitive species become dominant. Six studies found invertebrate abundance or species richness to be greatest at intermediate grazing (or cutting) intensity. Similarly, it is assumed that bird diversity peaks at intermediate grazing levels because of reliance on invertebrates as a food source (three studies), or because intensive grazing increases the risk of nest predation/trampling for ground-nesting birds (three studies). However, one study found that insect diversity was greatest on ungrazed sites, and another found no relationship between plant species richness at the local scale and bird diversity. The authors conclude that trade-offs may exist between the grazing requirements of different taxa, and that the limited evidence base necessitates a flexible, site-based approach. Forty-two studies were included in the review.