Agroforestry

“Agroforestry is the practice of deliberately integrating woody vegetation (trees or shrubs) with crop and/or animal systems to benefit from the resulting ecological and economic interactions.”25

Agroforestry combines elements of agriculture (agro) and trees (forestry) in sustainable production systems combining the production of a wide range of products including food, fuel, fodder and forage, fibre, timber, gums and resins, medicinal products, recreation and ecological services (Dupraz and Liagre, 2008). Agroforestry has been identified as a ‘win- win’ multi-functional land use approach that balances the production of commodities with non-commodity outputs such as environmental protection and cultural and landscape amenities (McIntyre et al., 2009). Key characteristics that distinguish agroforestry systems from agriculture and plantation forests include greater structural and functional complexity, an emphasis on multipurpose trees, and the production of multiple outputs balanced with protection of the resource base (Nair, 1991).

Agroforestry systems have traditionally been important elements of temperate regions around the world, evolving from systems of shifting cultivation towards more settled systems

25

involving agriculture, woodland grazing and silvopasture, with fertility transfer from woodlands to cultivated land via manure (Maydell, 1995; Eichhorn et al., 2006). European examples include:

i) Agroforestry systems of high nature and cultural value such as Dehesas in Spain, and wood pastures and parklands across Europe. Such systems also include hedgerow systems in northwest France and the UK;

ii) The intercropping and grazing of high value tree systems such as grazed orchards or the intercropping of olive orchards;

iii) agroforestry for arable systems such as alley cropping systems;

iv) agroforestry for livestock systems such as woodland eggs and poultry or the combination of trees with pigs, cattle, or sheep.

Traditional agroforestry systems in the UK include: wood-pasture, such as the New Forest, which features some of the oldest and widest trees in Europe, providing valuable resources for a wide range of associated biodiversity, as well as having historical and cultural value (Isted, 2005); parklands, which were developed in 18th century Britain for aesthetic reasons, but the economic value of their open grown timber for ship building was subsequently recognised (Sheldrick and Auclair, 2000); and multi-functional hedgerows.

Modern commercial agroforestry systems such as silvoarable and silvopastoral systems integrating trees into agricultural systems are in their infancy in the UK, but becoming increasingly widespread across a number of European countries where policy support is available for establishing new systems (e.g. an estimated 3000 ha per year established in France). However, agroforestry research sites have a longer history within the UK, with networks of silvopastoral and silvoarable trial sites established in the late 1980s/early 1990s. Originally established to investigate agroforestry as a means of taking land out of production or reducing productivity during a period of food surpluses (Hoppe et al., 1996), it was soon apparent that agricultural production could be maintained despite the introduction of trees so funding for agroforestry research was gradually reduced (Sibbald, 2006).

Perhaps the most commercially successful example of agroforestry in the UK is the production of ‘Woodland Eggs’26. Organic and non-organic free range eggs and chickens are produced from approved ‘woodland farms’ where chickens have access to woodland. Through a partnership between Sainsbury’s and the Woodland Trust, there are now almost 200 farms involved and, since 2004, over 300,000 trees have been planted. Farmers must comply with strict guidelines to receive a bonus payment of 2p for every dozen eggs; the Woodland Trust also receives a donation of 1p per dozen eggs and 2p per chicken sold. Recognising the animal welfare benefits of increasing tree cover, in 2007 and early 2008, all laying hen producers within the McDonald’s Restaurants UK supply base (286 producers) were required to plant, if not present already, 5% of the total range area in trees (Bright et al., 2011; Bright and Joret, 2012). The Pontbren Project, a farmer-led initiative that used woodland management and tree planting to improve the efficiency of upland livestock farming within one of the wettest areas of the UK, has been a highly successful example of the multiple benefits of integrating trees and woods into farm management (Woodland Trust, 2013). A group of ten farmers managing a total of 1000 ha within the Pontbren catchment near Welshpool came together in 2001 to make their businesses more sustainable by planting more than 10 miles of hedges and 120,000 trees and shrubs to provide shelter for livestock. It soon became apparent that tree planting not only benefitted the farm business and wildlife habitats but also reduced water run-off during heavy rain, and the project became the focus of scientific research into the effects of land use in catchments prone to flooding (Jackson et al., 2008).

26

There are a number of unique agroforestry systems that have been established by UK farmers over the last 15-20 years, each system designed to meet specific needs and challenges.

Wakelyns Agroforestry, run by Martin and Ann Wolfe, is a diverse organic agroforestry system in eastern England which incorporates four silvoarable systems; short rotation coppiced (SRC) willow, SRC hazel, mixed top fruit and nut trees, and mixed hardwood trees with 10-12 m-wide crop alleys between tree rows. The reasons behind establishing such a diverse system were manifold: to reduce pest and disease pressure by increasing the distance between individuals of the same species; to increase biodiversity including beneficials such as pollinators and natural enemies; to provide resilience to a changing climate; and to diversify production and reduce the risks associated with farming single commodities.

Arable agroforestry at Wakelyns, Suffolk (Photos: ORC (L), Permaculture Association (R))

Whitehall Farm is a 120 ha arable farm on Grade 1 fen soil near Peterborough, Cambs, managed by tenant farmers Stephen and Lynn Briggs. Previously managed as an intensive arable system, the eastern half of the farm entered into organic conversion in 2008, while the rest entered conversion in August 2009. The western 60 ha was developed into an apple orchard/crops agroforestry system in October 2009 with 4,500 apple trees, consisting of 16 varieties (10 commercial and 6 traditional) planted in rows (NE/SW orientation) 27m apart, with 3m spacing of trees within rows. The understorey was sown before tree planting with a 3m band of nectar flower mixtures, wild bird seed mixtures and legumes. The 24 m remaining between rows is cropped on an organic rotation that includes cereals, field vegetables and fertility-building leys. The drivers behind planting agroforestry include Stephen and Lynn’s desire to increase the enterprise diversity away from just cereals, to reduce soil erosion and to increase biodiversity.

Shillingford Organics is situated on a 140 ha farm just three miles from the centre of Exeter, owned and managed by Martyn Bragg. 18 ha are dedicated to growing organic vegetables, mostly for an organic vegetable box scheme where subscribers buy a box of mixed vegetables, herbs, salad leaves, edible flowers and some fruit once per week. Recently tree strips with apple trees have been introduced into the vegetable plots with the aims of increasing biodiversity, sheltering early vegetable crops, increasing the variety of crops to sell, and to provide interest for customers visiting the farm.

Grain legumes, crimson clover with trees at Shillingford Organics(Photos: J Smith/ORC)

Martin Crawford started establishing a forest garden on a 0.85 ha field at Dartington Estate

in South Devon in 1994. The forest garden is now an excellent demonstration of a self- sustaining system with a highly diverse

range of species which produce fruits, nuts, fungi, edible leaves, medicinal products, timber and other woody products. The system is robust to pests and diseases and resilient to the climatic extremes experienced over the last few years. Martin has written widely on his experiences, in particular Crawford (2010).

Martin Crawford demonstrates his forest garden at Dartington (Photo: J Smith/ORC)

Andrew and Hilary Mylius run Brackmont Farm and Forestry at the St Fort Estate in Fife. This mixed arable/grassland/woodland estate of 600 ha has pedigree sucklers, one herd of 85 pedigree Aberdeen Angus and one herd of pedigree Lincoln Reds. Trees were first planted on the estate in 1972 with the aim of providing shelter for the cattle and the farmhouse, and to reduce soil erosion. Further tree planting followed in 1994 to provide more shelter as amenity plantations for landscape and shooting. These woodland patches have areas of highly productive pasture, and so the cows and calves are moved in and out as the weather dictates, to take advantage of the grass growth and shelter from the trees. The ambience and sporting use of the

estate has improved, and the suckler herd has been expanded without new sheds being required. The Scots pines are expected to yield saw logs in the future.

Livestock sheltering under pasture agroforestry, Brackmont Farm (Photo: J Smith/ORC)

There is increasing evidence on the potential benefits of agroforestry in temperate developed countries (Jose, 2009; Smith et al., 2012; 2013a; see also Chapter 4). In particular, such systems have the potential to increase total biomass production, as measured by Land Equivalent Ratio (LER; see section 4.2), whereby the yield from growing crops in combination is greater than if the two crops were grown separately. Trees typically have longer growing seasons than annual crops and can capture more solar energy and nutrients during the year as a result.

The impact of agroforestry on the environment occurs at a range of spatial and temporal scales; externalities from farming systems impact the environment and society at regional or national scales. Agroforestry systems are multifunctional but most research focuses on a single function. One of the few studies to consolidate the multiple services from a single agroforestry system reports on ten years of research on agroforestry strips of hybrid plane (Platanus hybrida) and the shrub Viburnum opulus in north-east Italy (Borin et al., 2009). The young tree strips reduced total runoff by 33%, N losses by 44% and P losses by 50% compared to non-buffer controls, while a mature buffer reduced both NO3-N and dissolved

phosphorus by almost 100%. Herbicide abatement was between 60 and 90% depending on the chemical and time since application, and it was calculated that the buffer strips sequestered up to 80 t C ha-1 yr-1. The tree strips caused negligible disturbance to maize, soybean and sugarbeet yields, and contributed to increasing the aesthetic value of the landscape based on a visual aesthetic index formulated from people’s preferences during interviews (Borin et al., 2009).

Field experiments have by necessity been restricted to studying the point-scale or farm-scale effects of incorporating trees and crops/livestock; modelling approaches have provided a means of extrapolating how these fine-scale processes impact on a landscape-, regional- and global-scale. Palma et al. (2007b) showed through computer simulations that silvoarable agroforestry in Europe could reduce soil erosion by up to 65%, reduce nitrogen leaching by up to 28%, sequester between 5 to 179 t C ha-1 and increase landscape biodiversity by an average factor of 2.6.

Porter et al. (2009) calculated the values of market and non-market ecosystem services of a novel combined food and energy agroforestry system in Taastrup, Denmark. Belts of fast- growing trees (hazel, willow and alder) for bioenergy production are planted perpendicular to fields of cereal and pasture crops, and the system is managed organically with no inputs of pesticides or inorganic N. Field-based estimates of ecosystem services including pest control, nitrogen regulation, soil formation, food and forage production, biomass production, soil carbon accumulation, hydrological flow into ground water reserves, landscape aesthetics and pollination by wild pollinators produced a total value of US$1074 ha-1 of which 46% is from market ecosystem services (production of food, forage and biomass crops) and the rest from non-market ecosystem services. Porter et al. (2009) then extrapolated these values to the European scale and calculated that the value of non-market ecosystem services from the system could exceed the value of European farm subsidy payments in 2009.

Despite these benefits, both farmers and policy-makers have reservations about the potential for agroforestry systems. As part of the EU-funded AGFORWARD project22, 40 stakeholder groups27 have been established across Europe, and farmers were asked to identify the key positive and negative issues associated with the system. While they supported many of the benefits identified here, they also highlighted concerns about complexity (and the impact of this on management), labour and machinery costs.

27