How are we going to tackle agriculture’s enormous contribution to the climate and biodiversity crises? One of the few things everyone agrees on is that it won’t be easy, and part of the reason for this is the huge amount of disagreement around the viability and sustainability of many of the proposed solutions. Moving to faster-growing breeds of livestock, for example, could risk delivering carbon gains at the expense of biodiversity and animal welfare. There are, however, some measures with more universal support, and one of the most potentially significant of these is agroforestry.
Traditionally defined as the growing of commercially productive trees and agricultural crops on the same piece of land, agroforestry is, despite its new-found fame, a very old practice – though one which has sadly been almost entirely lost from our landscape. In contrast to the prevailing mindset around trees and food production, which largely sees these two land uses as mutually exclusive, agroforestry systems are designed in a way that provides benefits to both enterprises, while also generating a range of environmental gains such as improved soil health, reduced runoff, increased biodiversity – and of course, carbon sequestration.
It’s no wonder, then, that agroforestry has received widespread support from many different quarters over recent years. But with a range of different possible approaches and few on-the-ground practitioners, what might its implementation at scale actually look like? Thanks to the pioneering work of the likes of Stephen Briggs and his alley cropping system of apples and cereals, we have proven models that show how agroforestry can work on cropland. But with the exception of some research trials carried out in the 1980s, there has, as far as I’m aware, been very little research done into how agroforestry might be best implemented in grassland areas. The approach these trials took – which was to plant evenly spaced trees at very low densities, with each plant individually protected from browsing – was designed for a study into the effects of canopy cover on grass growth, and so was never meant to be used as a model for production. In the absence of alternatives, however, it has become the template for silvopasture (which mixes trees and livestock) in grant schemes and modelling exercises – despite it being an approach that doesn’t provide quality timber, and which is prohibitively expensive when implemented over an area of any real size. Might there, then, be better models for agroforestry in grassland areas?
Back in 2009, we decided to have a go at a different approach at the Mains of Fincastle, our 540 hectare hill farm with beef and sheep in Highland Perthshire. The aim was to create areas of ‘wood pasture’ capable of producing quality timber alongside continued grass growth for our stock. To achieve this, a mixture of hardwood trees were planted at 1600 stems per hectare (three times the density of the research trial mentioned above) with the design a rowed pattern with wide alleys left empty to provide a 60% canopy cover across the whole site.
The two new plots, totalling seven hectares, were also fenced off from sheep for five years and cattle for nine years, to allow the trees to grow to a point where they were safe from stock – a much cheaper approach to tree protection at the scale we were working at, because the fencing costs were well below those that would have been required for individual guards.
Twelve years have now passed, so how is it going? Well, you can see what one of the plots looks like in the picture at the top of this piece. It’s still very early days, but in many ways, it’s been a great success. Our stock have benefited from the shade and shelter provided by the trees, and the cattle in particular love browsing the leaves – unsurprising, given they were originally a woodland animal. Probably the biggest positive for the stock, however, has been the boost to our early season grass growth, made possible by the micro-climate that has developed amongst the plantings. With spring the time of year that we are most short of feed, this has proven a real benefit for the management of our stock, and one which more than outweighs the reduction in summer grazing caused by the shading of the tree leaves and the resulting suppression of grass growth.
It’s still too early to tell what sort of timber these plots will produce, but the trees are growing well so far, so we remain hopeful that our planting design will be successful on that front. This applies to the impacts on biodiversity too: while some species of woodland bird have already appeared, the incredible diversity of mature wood pasture systems found across Europe suggest that the biggest wildlife gains are probably still to come.
But perhaps the most interesting outcome – and given the current obsession with carbon, certainly the most relevant – has been the impact of these plots on our farm’s emissions footprint. Unfortunately, the AgreCalc farm carbon calculator we use isn’t yet able to account for sequestration from pasture woodlands, but using assumptions and data from Forest Research, we have roughly calculated that these seven hectares of wood pasture are currently offsetting a little over a third of the emissions (as measured using GWP100) produced from our farm. This means that we would be able to cancel out all of our farm’s emissions by planting around 15% of the total farm area with wood pasture – something which we could definitely achieve without any real loss of agricultural production.
There are, of course, different ways we could have designed these plots, but from what we’ve seen so far, we’re comfortable that the approach we’ve taken works for us. So how might it work on other farms? It’s a model with much greater canopy cover than the likes of Stephen Briggs’ alley cropping system, so it wouldn’t really be suitable for land that is used for cropping, be that for arable or hay and silage. But on farms like ours where there are extensive areas of lightly stocked rough grazings, excluding stock from some of this land for five to ten years while the trees establish safely would in most cases be quite easily accommodated without any loss of agricultural production, providing there was a more efficient rotational grazing system in place.
Whatever the model used, the widespread uptake of agroforestry in our uplands represents a massive opportunity. Above all else, it offers a means of increasing tree cover that doesn’t necessitate the total cessation of agricultural production, and so avoids the loss of all the social, economic and biodiversity benefits that farming brings to our upland areas. There is, however, much more work to do before upland agroforestry can be realised at scale. Some of this will involve the development and study of systems more suitable for upland areas – important if we are to carry out more accurate modelling of carbon sequestration, and to get a better understanding of potential management costs and earnings. Having a good template will also be critical to designing good grant schemes, the current lack of which represents one of the main barriers to uptake.
Agroforestry is by no means a panacea, and it won’t replace the need for new woodlands, be they native or commercial. But providing beleaguered hill farmers with a viable means of getting towards net zero, and in a way that could improve both the financial and environmental performance of their business, is something we surely have to support if we genuinely care about the future of our upland areas.
After capturing the family’s agroforestry work on camera, Robert’s brother, Patrick Barbour won the search for Scotland’s climate friendly farming champion – a competition organised by NFU Scotland’s Next Generation group and supported by Royal Bank of Scotland. It encouraged Scotland’s farmers and crofters to record on video the many steps they are taking to reduce emissions and deliver wider environmental benefits. You can watch the video here:
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