Silvopastoralism

Animal agriculture contributes to climate change, land degradation, water pollution, and the loss of biodiversity. These problems are detailed by the UN report Livestock’s Long Shadow, which goes on to suggest how this impact can be mitigated. The report suggests silvopastoralism as a technique that can reduce both the climatic impacts and the land degradation caused by livestock.

What is silvopastoralism?
Silvopastoralism belongs to a group of practices known as agroforestry, which ranges from subsistence gardens in tropical rainforests to shelterbelts of trees that act as windbreaks. When silvopasture is practised, trees are grown in the same area where livestock are raised. Animals may graze in existing forests, or trees may be grown in pastoral land. The trees provide fences, fodder, shade or erosion control in the area where livestock are grazing (1).

How can silvopastoralism help the environment?
Silvopastoralism can help mitigate climate change, and protect soils from degradation. Trees act as carbon sinks by absorbing CO2 as they grow. For this reason plantations of timber are likely to become part of a carbon credit economy. Trees also contribute to environmental protection in grazing areas by protecting steep land from erosion. In addition biodiversity is greater in a silvopasture than in standard pastures.

How can silvopastoralism help farmers?
Silvopastoralism can reduce the environmental risks of a monoculture by protecting grazing land from heat and wind, but trees that are too dense can compete with grasses for light and moisture. The animals themselves can benefit from shade and shelter, and may use the trees for fodder during dry times. Poplar and willow trees are used in New Zealand to provide fodder as well as stabilising steep slopes (2).

Financially trees can be sold either as as lumber or as carbon credits. Analysis in Queensland Australia suggests silvopastoral eucalypt plantations where timber is sold as well as livestock can be more profitable than conventional grazing. However natural regrowth strips would only become financially worthwhile for farmers in semi-arid Queensland if there was a price on carbon (3).

In summary
Silvopastoralism can help reduce livestock’s shadow, but most sources express concern about the ease of implementing this system, and whether it is affordable or financially advantageous for farmers. Studies must make assumptions on the financial benefits of growing timber because of time limits (trees take many years to be saleable as timber) and uncertain prices (in Australia there is currently no price on carbon, but having one could make silvopasture more profitable than standard grazing). Despite these difficulties in analysis it seems clear that there are environmental benefits to silvopastoralism, and it can be made financially viable.

Both governments and markets have a role in deciding whether environmentally friendly farming practices are rewarding for farmers. What information would you want to have about how your food was produced before you would pay extra for an environmentally friendly product?

References
(1) Advances in Agroforestry, Volume 2, 2005
DOI: 10.1007/1-4020-2413-4
Valuing Agroforestry Systems: Methods and Applications
Alavalapati J.R.R. and Mercer D.E.
(2) Agroforest Syst (2009) 76:327–350
DOI 10.1007/s10457-008-9186-6
Silvopastoralism in New Zealand: review of effects of evergreen and deciduous trees on pasture dynamics
Benavides R., Douglas G.B. and Osoro K.
(3) Small-scale Forestry (2010) Online prepublication
DOI 10.1007/s11842-010-9126-y
The Bioeconomic Potential for Agroforestry in Australia’s Northern Grazing Systems
Donaghy P., Bray S. Gowen R., Rolfe J., Stephens M., Hoffmann M. and Stunzer A.
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