Individual study: A literature review of the effects of sheep and cattle grazing in plantation forests
Adams S.N. (1975) Sheep and cattle grazing in forests: a review. Journal of Applied Ecology, 12, 143-152
In Britain, there is no experimental evidence and little general information concerning the effects of livestock grazing in woodlands and forest. Plantation forest establishment in upland Britain often involvs fencing to exclude livestock, to protect young planted trees. Likewise in semi-natural wooded areas of the UK, livestock are generally excluded. In some other temperate regions of the world however, grazing and forestry are successfully integrated and help maintain a herb-rich ground flora. In order to guide management in the UK, a literature review was undertaken to draw together experience of management findings elsewhere.
A global literature review was undertaken to assess the effects, both detrimental and beneficial, of sheep and cattle grazing in forests. The review focuses on forestry and plantation woodland, but the findings have some relevance to woodlands and forests in general.
Livestock were invariably found to inflict some damage to trees, sheep generally by browsing and cattle additionally by trampling. However, such damage is minimized by excluding stock until trees (in plantation situations) are above browse height. Tree species differ in susceptibility to damage. Non-native, Sitka spruce Picea sitchensis, the main plantation species in upland Britain, appears unpalatable to sheep and cattle. There are a few reports of chemical impoverishment of forest soils by grazing in unfertilized forests. There are reports of physical damage to forest soils (several papers reporting this refer to cattle).
Several papers report examples of successful use of livestock in forest management in terms of controlling woody understorey vegetation, with benefits to tree growth and in some cases, ground flora. In Britain, stock could potentially play a similar role in helping to eliminate competing vegetation.
The literature is unanimous in that for grazing to be successful it must be applied at a suitable livestock density, and duration of grazing and grazing season be appropriate to the situation.
Note: The compilation and addition of this summary was funded by the Journal of Applied Ecology (BES). If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://links.jstor.org/sici?sici=0021-8901%28197504%2912%3A1%3C143%3ASACGIF%3E2.0.CO%3B2-L