http://conservationevidence.com/individual-study/5501
Groome G.M. & Shaw P. (2015) Vegetation response to the reintroduction of cattle grazing on an English lowland valley mire and wet heath. Conservation Evidence, 12, 33-39
Abstract.
We report the results of a nine year study of the effects of restoring low-intensity cattle grazing on the post-fire recovery of vegetation on the lowland valley mire and wet heath of Folly Bog, Surrey, UK. Four distinct vegetation communities were studied, with repeated recording of quadrats (n = 652) inside and outside grazing exclosures.
Species richness increased across the valley mire, largely as a result of grazing-induced decreases in purple moor-grass Molinia caerulea and litter and increases in bare ground. Uncompetitive liverworts and waterlogging tolerant graminoids were particularly favoured. Purple moor-grass and litter removal also encouraged the spread of bog-mosses Sphagnum spp., although trampling in the wettest vegetation resulted in locally severe damage to the moss layer. On the firmer substrates of the wet heath, there were no such deleterious trampling impacts. Here, both bog-moss cover and species richness increased significantly, largely due to suppression of shade-producing heather Calluna vulgaris and litter, and the maintenance of bare ground.
Our results reveal that the resumption of low intensity cattle grazing had many positive conservation benefits. However, site managers need to consider grazing on a site-by-site basis and retain flexibility to change stocking times and levels as conditions dictate. Other forms of management to supplement grazing will most likely continue to be required.
[The Exmoor ponies of the Sussex Pony Grazing & Conservation Trust are starting to gain similar results on a large heathland site in the Ashdown Forest area.]