Agroforestry probably offers the best single answer to flood control – and a great deal else besides. It must become a priority.
If there was a one-word answer to all the world’s problems, it surely would be trees.
Trees are the climax vegetation: what grows if it’s not too dry (though many grow well in semi-desert) or too wet (though many live happily through flood and some live almost permanently with their roots submerged) or too cold (though the boreal forests of Canada and Siberia are bigger than Europe).
A Nordic myth says that trees hold the earth and the sky together, and so in a way they do: miraculously drawing the carbon that is their principal component from the air, and their water both from the ground and the air. For example, the giant Coastal Redwoods of northern California get about a third of their water from the fogs off the Pacific they get most of their nutrients from the soil (helped by their mycorrhizal companions), but also from the air, including the various nitrogenous pollutants known as collectively as NOx.
The official British attitude to trees these past centuries has been a mixture of aesthetics of an aristocratic kind and hard-headed utilitarianism.
The former took the form of Capability Brown-style landscapes, inspired in large part by Baroque and Romantic landscape painting (for nature followed art). The utilitarian approach has been inspired by our military, commercial, and imperial aspirations.
Our ancestors felled entire forests of oaks but also planted them to build timber-framed houses and the navy. Later, more trees were grown and felled to fuel the navy’s new steam ships, and when coal replaced wood as the fuel of choice, fast-growing conifers were raised on a heroic scale for pit-props. In the colonies, eucalypts and teak in particular fulfilled the same purpose.
It’s not all bad, Britain does have some fine trees and woods, but it’s high time for a change – not least of attitude.
We need to move beyond mere anthropocentricity: the idea that human beings are the only creature that really matter, and the rest is ‘natural resource’, towards a ‘biocentric’ or ‘gaiacentric’ morality and metaphysic, in which we see ourselves as part of the ecosystem, with all living creatures important in their own right.
On the utilitarian front we need in particular to rethink the relationship between trees and farming. The two have generally been seen to be at odds – pioneer farmers begin by clearing the forest. Yet as many have shown, trees and farming can operate to their mutual advantage.
Hedges, windbreaks, alleys, copses, woods, or even isolated trees provide shelter and fodder for livestock which for the most part are browsers as much as grazers, adding micronutrients that may be lacking in grass, especially in monocultural grass.
Trees provide microclimates for both animals and crops, even cereals, which may be heat-stressed in large open fields. The diverse ecosystem, replete with predators, helps to contain pests.
As a bonus, trees on farms have commercial value for on-the-spot fuel and fencing, fruits and nuts, dyes, perfumes and finally for timber, both for structure and for high-value veneers. ‘Land equivalent ratio’ is the essential measure. Trees plus crops should be worth more per unit area than either would be worth if grown as monocultures.
But perhaps the greatest practical reason for taking trees seriously is climate change.
Trees sequester carbon and are also the most powerful antidote to flood, which will become worse as the world warms up. It is better to stem the flow of surplus rain from the uplands than to ‘manage’ floods that could have been prevented, with heroic civil engineering.
A new report from well-informed local people on the Somerset Levels, Reimagining the Levels, Making the Connections, proposes that tree cover in the whole catchment should at least be doubled.
This will be challenging logistically and economically. Though trees at present cover only 6 per cent of the catchment, a doubling would take us only to the national average of 12 per cent.
But Britain as a whole is seriously denuded. Tree cover in France and Germany is around 30 per cent. As a matter of urgency Britain needs at least to double its tree cover over the whole country, with more in flood-prone areas. This must be planned by true experts, not by bureaucrats and accountants as has become the norm. We must not repeat the disastrous mistake of a few years ago when commercial conifers threatened to ruin the wondrous wetlands of Sutherland’s Flow Country.
There’s a lot to do on all fronts – conservation, ‘amenity’ – but the priority, right now, must surely be to encourage agroforestry.
Some countries have been practicing agroforestry for centuries, in many forms. Many more are now waking up to it. Defra isn’t because there is no short-term profit in it so it is not considered ‘realistic’. However next January’s Oxford Real Farming Conference aims to challenge those perceptions with a session on the benefits of agroforestry, as well as discussions on how to overcome the barriers to its successful practice.
Colin Tudge October 20 2016