In the UK, silvopastoral systems are typically those in which trees are planted at wide spacings into grazed pastures. Such systems could potentially reduce agricultural production in the long term, but if there is sufficient complementarity between the requirements of trees and grasses for light, water and nutrients the total production of grass and timber together may be higher than for trees and grass grown in equivalent areas of monoculture. Research in the UK in both the uplands and the lowlands has demonstrated that there is no reduction in agricultural production nine years after planting trees at 400 per hectare (5m x 5m square planting).
Silvopastoral systems have also been shown to increase numbers of species of ground insects and numbers of species of birds compared to conventionally grazed pastures. Increased environmental diversity can therefore be expected.
Our experience shows that sheep use the trees for shelter from wind. This could provide significant animal welfare benefits. However the fact that the sheep do spend time close to trees results in greater soil compaction close to trees with the greatest compaction when trees are planted at very low densities. We recommend that trees are planted at no less than 400 per hectare to ensure good establishment.
In order to protect the trees from the sheep during the establishment years, we recommend that, for broadleaved species, conventional rigid plastic tree shelters are used. For conifers it is better to use a much wider net guard to ensure good growth form.
For practical information on how to plan, set up and manage a silvopastoral agroforestry system, go to the Silvopastoral Agroforestry Toolbox Website.
Another form of silvopastoral agroforestry is woodland pasture, or forest grazing. Some people do not regard this as a form of agroforestry as such, as it is in effect the use of woods/forests for agricultural grazing. Wood pasture is a very old land use in the UK and Ireland, as witnessed by the fact that Commoners of the New Forest still have the right of common pasture for their livestock in the New Forest. Wood pasture and parkland is a priority habitat within the UK Biodiversity Action Plan.