Agroforestry - growing trees on farms - is nothing new, in fact its decidedly ancient. The patchwork of copses, briars, standards and hedgerow trees we see across the countryside today are testament to the fact that our farmed landscape was actually carved out of the woods in the first place. Despite this, the estimated 14,000 miles of hedgerows and thousands of farmland trees we’ve seen scrubbed up within the space of a silvicultural-fortnight suggest that our tolerance for mixing trees with farming is not what it once was.
Of course, parkland trees weren’t always just romantic backdrops for period dramas, and there are practical reasons too why hedgerows contain a diversity of species. And although grazing sheep in orchards may be one of the only tenuous examples still widely practiced - there are still those who champion the role of the tree in the farming landscape.
Agroforestry has seen something of a two-pronged renaissance over the past decade or so. The first of these was arguably inspired by the late Robert Hart, a passionate agroecologist who dedicated his later life to creating the UK’s first temperate forest garden at his home in Shropshire. While Robert regarded his plot very much as an experiment, there’s no denying that his work has been largely responsible for sparking today’s forest gardening movement, embraced by permaculturists up and down the land.
The second prong of Agroforestry’s revival has been led by a handful of the UK’s leading forestry colleges and universities, most notably Bangor and Aberdeen. Initially inspired as a solution to the bottom falling out of the homegrown timber industry – planting trees on farms has since been promoted as an economic incentive for struggling farmers as well as a land management tool for anything from flood prevention to bioremediation.
Despite a good deal of enthusiasm however, there are still only a handful of farms deliberately practicing agroforestry in the UK while forest gardening remains the preserve of urban allotmenteers and small scale experimental gardeners.
So if it really lives up to all the talk – why haven’t we seen a full-scale agroforestry revolution in the UK?
Agroforestry comes in two broad categories; silvo-pastoral - trees and pasture, and silvo-arable - trees and crops. To many people it may seem contradictory to plant trees on the same plot of land as you’re raising crops or animals, but believe it or not there is undeniably somethig to be gained from this symbiosis. And while this is arguably displayed every time a hedgerow tree shelters a calf, or drops its leaves on a patch of spring wheat, a handful of dedicated individuals have made it their business to demonstrate agroforestry’s full farm-scale potential.
Seeing the Sheep for the Trees
Henfaes research farm, clinging to the bleak north coast of Wales, is the UK’s longest running silvo-pastoral research station. Since 1992 the 14 hectare site has hosted a flock of Welsh mountain ewes grazing in and amongst several blocs of sycamore and alder trees planted in various patterns and at various spacings. The idea of the experiment is to measure the effects on the productivity of both the sheep and the trees compared to a control next door where trees and sheep are kept entirely separate.
The site is owned by the School for the Environment and Natural Sciences at nearby Bangor university where Ian Harris is the research farm manager. 'What we’re demonstrating here at Henfaes are the multiple benefits that can be achieved with a silvo-pastoral system' Ian tells me. There are of course the obvious benefits to the sheep who are sheltered in the winter and shaded in the summer, and also to the trees which inevitably benefit from nutrient cycling by the sheep and grazing which controls competitive seedlings. But Ian and his team have discovered some surprising, and less obvious benefits.
Both soil structure and fertility have been improved by the tree roots themselves and their associated micorrhizae, but also by the cycling of leaf matter which brings in earthworms, microbes and biota. The alder blocs demonstrate that nitrogen can be fixed naturally in the soil using agroforestry while the indirect benefits we’ve demonstrated include improved groundwater infiltration and increased biodiversity as the trees bring with them their own micro-habitats and food chains.”
The model Ian is describing has been practiced for centuries in temperate orchards around the world where farmers have made the most of a rich crop of spring grass before the trees come into leaf. Although the results of the experiment show no measureable increse in the growth rate of the ewes under the agroforestry planting there is, importantly, no measureable difference either suggesting that the presence of the trees is at least not detrimental to the herd.
In addition to the environmental benefits Ian describes he also suggests why this system could appeal to established livestock farmers, particularly in the west of the UK. 'From the farmer’s point of view he’s improving the productivity of his land, improving the health of his soil and, looking at the longer term, generating additional income from the tree thinnings. Importantly we’re demonstrating all of this on an exceptionally exposed site. We’d like to think that another farmer trying this on a more sheltered site elsewhere in the UK would see a marked improvement on what we’ve achieved.'
A couple of hundred miles south east from Henfaes is Wakelyns agroforestry research farm in Suffolk. Wakelyns is arguably the silvo-arable partner to Henfaes where Professor Martin Wolfe has established six separate alley cropping treatments across 23 hectares. The experiment was set up in 1994 to demonstrate; 'how immensely productive natural systems can be. using no inputs other than sun, air, soil and water.'
Mixing trees with crops is slightly more restricted than mixing trees and animals for the simple reason that the crops need to be harvested mechanically requiring relatively straight rows. Taking this into account, trees are planted in rows along a north-south axis with a cropping alley in between them, they are also pruned regularly to remove their lower branches. This improves the quality of the timber, allows the crops to be harvested conventionally and keeps shading to a minimum.
Martin Wolfe is refreshingly down-to-earth in describing the Wakelyns experiment: 'Put simply - agroforestry is creating a woodland edge habitat without a woodland' he explains. 'Woodland edge is perhaps the most diverse habitat we have in this country. What we’re doing is demonstrating a compromise between appropriate agricultural systems and this natural world approach.'
Wakelyns uses cereals (wheat, barley, oats and others), clover ley and potatoes in the crop rotation, alley-cropped between rows containing several different tree species. 'We’ve found that a diversity of species increases productivity and resilience' Martin tells me, 'A diversity of trees means a concentration of one nutrient or another in the top soil in which the cereals are growing. Under an organic rotation we use no inputs at all to achieve seven to eight tonnes of cereals per hectare. This is largely down to the impact of the clover ley phase in the rotation together with organic matter and nutrients provided by the trees, the shelter which increases the average temperature and the presence of mycorrhizae which recycle both organic matter and nutrients.'
Like Ian Harris, Martin Wolfe is quick to identify the ways in which his soil has benefitted from silvo-arable planting. 'First and foremost soil structure is maintained by the continuous growth of tree roots in the soil. This means that infiltration is improved in times of flooding and water retention is improved during times of drought.'
Martin has also demonstrated how the productivity of his trees has benefited from the silvo-arable set-up. 'Obviously the trees respond to being thinned and having the usual competition from their neighbours controlled. We were however encouraged to find that our trees are considerably more advanced for their age than Forestry Commission guidelines for girth at breast height.' The net result of the Wakelyns alley cropping experiment with willow, for example, demonstrates a land equivalent ratio of 1.4 for this locality. This means that 1.4 hectares of monoculture production of willow and crop would be needed elsewhere in East Anglia to produce the same quantity of output as gained from a single hectare of alley cropping at Wakelyns.
Both Ian Harris and Martin Wolfe acknowledge that the benefits they describe have only been achieved because of the careful management of competition within their respective agroforestry systems. According to Ian 'It has taken a number of years to discover the correct balance of pruning to ensure the canopy is not too dense or too sparse, and we are still learning. It is important for trials like Henfaes to continue as we can learn from these mistakes and build a better picture of what efficient agroforestry looks like in the UK.'
Aside from the general models described above agroforestry systems can, and have been adapted to meet specific environmental needs from windbreaks to contour plantings, forage crops and riparian (river) buffer strips. Since 1999 Bangor university has been involved in a catchment-scale experiment on the Pont Bryn valley in mid Wales evaluating the potential of farm woodlands to regulate flood peaks downstream.
While both Henfaes and Wakelyns between them demonstrate the very real potential for agroforestry systems to be integrated into commercial farming in the UK, it is arguably at the other end of the spectrum, forest gardening, where there is currently the most interest - and certainly the most momentum.
In line with the popularity of Permaculture, which has ballooned over the past decade or so on the back of the green-lifestyle bubble, 'Forest Gardening' is now heralded by many as the panacea to the global food crisis. It appears to be extremely cool to drop the phrase amongst activist and permaculture circles while a simple Google search brings up more than 30 UK-based courses on the subject, scores of magazine articles and more than 120 books.
Martin Crawford is the founder of the Agroforestry Research Trust based at Dartington in Devonshire and arguably the country’s leading expert on popular forest gardening. Over the past decade Martin has created two-acres of agro-ecological bounty in this small corner of England and has upwards of 1,000 visitors to his plot each year. He describes a forest garden as: 'A three-dimensional garden of useful plants; trees, shrubs and ground cover plants, all designed to maximise beneficial interaction and minimise competition. The idea of a forest garden is to mimic the structure of a natural forest – specific to each locality – replacing non-edible natives with practical alternatives. I don’t just include edible plants but medicinal plants, plants for dying and plants for fibre.'
It seems the main differences between agroforestry and forest gardening are in terms of diversity and scale. Martin Crawford has an estimated 500 species of trees, shrubs and ground plants across his two-acre site, compared to around 50 species across 23 hectares at Wakelyns. 'In reality this is largely because I want to show the extent of what is possible, but most forest gardens I have visited will have around 200 species growing happily side by side' says Crawford. 'Forest gardens are traditionally designed for subsistence production and as a result tend to be on a scale that can be managed with hand-tools.'
Although he agrees that the popularity of permaculture has played a role in the recent upsurge in forest gardening, Crawford believes it also has a boarder appeal. 'People are starting to look for alternatives to mainstream agriculture. Yes there is certainly a crossover with permaculture but people are also starting to grow their own veg, allotments are taking off again and there is an interest in sustainability and resilience that is fulfilled by forest gardening. Interest is also growing from the mainstream gardening press and TV programmes.'
He strongly disagrees however that forest gardening is purely an urban phenomenon – 'It’s true that urban groups may find it easier to get funding for community growing projects and getting publicity, but in my experience there are just as many people creating forest gardens in rural areas. The courses I run see a complete cross section of people from urban students to rural youngsters and also retired couples.'
And while he is certainly enthusiastic about what he has achieved at Dartington he is also realistic about its limitations. 'Forest gardening can make a contribution to the future of food production but certainly can’t supply all of our needs. Carbohydrates for instance usually require a lot more sun than can be provided in a forest garden. Realistically forest gardening in this country is only ever going to provide for three to four people per acre - but its worth remembering that its not only food but also medicines and fibres.'
Taking it Mainstream?
It seems then that the practical evidence is there to convince us that agroforestry has indeed got something to offer both commercial farmers and smallholders alike. The challenge now seems to be more theoretical, in how to encourage a traditionally sceptical farming community that planting trees across their farmland is actually a good idea.
According to Ian Harris a lot of the problem is in the terminology. 'Rather than “Agroforestry” we are now moving towards talking about “farm woodlands” which could make the idea more accessible to farmers on the ground.' He also points out the very real concern that many farmers have with making such a long-term investment – 'Its also a perceived problem of tying-up farmland into one type of management for a number of years when our farmers tend to like to keep their options open to respond to the market.'
It could also be argued however that a lack of enthusiasm is a symptom of our disconnection from a holistic approach to land management. Martin Crawford believes that Agroforestry is not that easy for farmers to access because they’re not that comfortable with trees. 'For a long time now both agriculture and forestry have become so separated that the majority of our farmers don’t have the skills to manage woodlands and the idea of planting trees amongst their crops or livestock seems bizarre.'
There is however a precedent. In the 1950’s the British matchstick company Bryant & May Ltd paid livestock farmers in East Anglia to plant poplar trees at wide spacings in their pastures to provide high quality matchwood. The initiative was taken-up enthusiastically and lasted for around 25 years until it became cheaper to buy imported slow-grown poplar from eastern Europe and the payments stopped. This suggests that farmers could well be persuaded to try some form of agroforestry, but only if the money is right.
And the money could very soon be right. In 2011 the Foresight report on 'The Future of Food & Farming' highlighted the role of agroforestry in achieving multiple benefits in the farming systems of the future. Under the heading 'Reducing GHG emissions from the global food system' the report highlights agroforestry’s potential for 'long-term carbon capture on farmland” as well as “reducing soil erosion, producing renewable fuels and the storage of carbonised wood (biochar)'. As the age of the carbon-economy dawns it is easy to see how agroforestry could very soon be subsidised out of obscurity.
Reluctantly, Martin Crawford agrees that agroforesry is only really going to take off when farmers are specifically paid to do it. 'EU CAP funding at the moment does not incentivise planting trees on farms. However the most recent round of CAP reforms are set to encourage more mixed farming and direct environmental benefits. A few years down the line its not unfeasible to see it paying for agroforestry plantings. Although I certainly prefer change taking place from the bottom-up, it may be that in reality this change must be encouraged from the top-down.'
Martin Wolfe agrees, however, he cautions against the very real possibility that the roots of the science could well be lost in the process. 'We need to be careful that we don’t simply pay farmers to grow monocultures of cereals underneath cloned lines of trees in an effort to chase a payment for a certain model of farming. We don’t gain anything from chemical farming whether its done underneath trees or not. There needs to be a clear distinction which encourages a holistic approach that makes the most of the benefits of biodiversity and symbiosis.'
That there appears to be a reluctance among the farming community to adopt an agroforestry set-up, despite the demonstrations outlined above, shouldn’t come as a surprise. British agriculture has suffered enough misguided interventions over the past half-century that, sensibly, farmers tend to be suspicious of anything new. As Martin Wolfe points out however, the fact that agroforestry isn’t 'new' could well turn out to be its greatest asset: 'Until relatively recently most food production was some form of Agroforestry, woodpasture systems are traditional to the UK, people have forgotten this. Rather than introducing something new therefore, we need to modernise what was done everywhere else in the past. If done in this way agroforestry could very well be a stepping stone on the way from monoculture to agricultural diversity.'
Ed Hamer is a young farmer and co-editor of The Land magazine where a version of this article first appeared
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