In combating the dual crises of ecological collapse and catastrophic global heating agroforestry may present a promising and so far under-utilised tool. In the context of the Chew Valley agroforestry is of particular interest and may offer a “win-win”. The win of increased biodiversity, longterm carbon sequestration and continued or even increased food production.
Agroforestry incorporates trees and other woody perennials within agricultural systems with potentially mutualistic and beneficial interactions between tree and agricultural components. It can offer many economic, environmental and social benefits.
Silvoarable Agroforestry – is the integration of trees and/or other woody perennials within arable farming systems
Silvopasture Agroforestry – is the integration of trees and/or other woody perennials with livestock farming
Although agroforestry is not a well known or widely discussed in the UK it is beginning to receive increased attention in the media and more practical implementation by farmers across the country. Although agroforestry was only properly established as a science in the 1970s, the practice itself is thousands of years old and occurs all over the world in many different forms. From tropical homegardens, to tea and coffee plantations with overstory trees, to the Montados of Portugal utilising cork oak savanahs with grazing pigs, to the walnut and cereal alley-cropping practices in France and Short-Rotation Coppice systems in Germany, agroforestry is a wide-spread and established group of practices, although with yet a much greater potential for expansion.
Agriculture is a leading driver of habitat loss and greenhouse gas emissions globally. All types of agriculture covers approximately 70% of the land in England and historically the sector has been a major factor in land use change, including the conversion of natural forests to either pasture or arable use. Part of the barrier to wider implementation of agroforestry in the UK is the mindset that trees and agriculture are not friends and should not take place on the same piece of land. The government institutions and funding schemes reinforce this mindset and as such woodland remains the domain of foresters and agriculture that of farmers. But trees and agriculture may not be the mutually exclusive competitors they are often considered. Trees on farms, when effectively designed and managed can provide a dirth of environmental, economic and social benefits including: Improved biodiversity and habitat, wildlife coridors joining up otherwise individual parcels of land, reduced soil erosion, increased food security, carbon sequestration, increased nutrient cyling, flood mitigation, increased animal welfare, greater on farm productiveity, income and resilience, as well as cultural, social and ecosystem service factors (e.g. oxygen to breath, water and air filtraion, wood-fuel and building materials).
Common forms of temperate agroforestry practices that are appropriate for the British climate and farming context included; a) alley-cropping, the planting of rows of trees (food producing trees or trees for timber) and cultivating annual crops in the ‘alley-ways’ between the tree rows, b) silvopastoral practices, where livestock are grazed underneath a tree canopy c) hedgerows, ripparian buffers and shelter strips, where trees are utilised to offer an on-farm function such as boundary deliniation, wind aliviation, filtration of overland flow, micro-climate creation or woodfuel etc.
Agroforestry offers an opportunity to greatly increase tree cover by planting trees on agricultural land, without taking the land out of production and so provies an alternative/complimentary solution to our ‘oportunity woodland’ methodology, in answering the question of ‘where are the trees going to go?”.
As trees could be planted on arable and pasture land, agroforestry offers an integrated system with a wide range of benefits. If it was embraced by UK farmers what does this do to our Chew Valley woodland opportunity map? The entire map, minus human-habitaion and and infrastructure becomes an opportunity for increasing tree cover and as such for:
- Increasing biodiversity, habitat and ecological resilience
- Mitigating and adapting to to climate change, by sequestering carbon in above ground tree biomass and the below ground soil carbon pool and the possibility to provide low input, perennial food crops
- Diversifying farmer incomes while reducing soil erosion, increasing yield and mitigating flood risk
The accompanying maps contain a Woodland Statistics box for each parish that includes an estimate of the area of existing and potential woodland and the areas of arable and grassland in the parish.