Sustainable Footprint

What is ‘Agroforestry’?

Mixed agricultural systems combining trees with other crops used to ben very normal in landscapes inside Europe and outside. Fruit orchards with the young cattle grazing under the trees, rows of trees and hedges between the fields – in former times very normal - have disappeared mostly, even if you can find some still decorating the landscape. Combining agriculture with forestry, agroforestry, seems to be very oldfashioned, but research has shown that it is more productive than separat agriculture and forestry, up to 50%. You avoid the negative effects of monocultures.
In Europa we know two types of agroforestry: in northern Europe and the Mediterranian area. In the last region there is not only more agroforestry, but also more diversity in the systems, simply because more plant and tree species can grow there. Mixed systems can give the European countryside (and elsewhere) a chance to develop a more sustainable food production and more biodiversity. At the same time landscapes can be preserved that are not only beautiful, but also have a cultural historical value.
Tradional agroforestry in a modern form can preserve the good sides of mixed agriculture.

Tree products
Trees have economical value in 3 senses: they produce fruits, fodder and wood (for fuel, construction and litter). They give shadow and prevent erosion

Trees and water
Trees catch rain and improve condensationof water from mist or dew. When they are planted as windscreen, they slow down the movements of the air, and evaporation.

Afroforestry: poplars and cows

The roots of trees go deeper than those of smaller plants; they pump water from deeper layers and makei t available to more superficial root systems. In colder climates they can prevent freezing of the deep msoil

Trees and nutrients
Competition between trees and crops can happen, but the roots of trees can also bring nutrients from deeper layers up, where the crops can use them. They can prevent washing out of nutrients. Throug falling leaves and roots the nutrients are recycled, raising the ecological efficiency, making the system more sustainable. Trees can atract animals by offering them hiding and nesting possibilities; this also brings in more nutrients.

Farming with trees
Te most important aspect of agroforestry is that there can be several harvests before the trees are big, the land produces while the trees are small.
It is important to make a good plan and combine the right species.
Mixed systems can produce more than monocultures because the trees can use resources that otherwise would not be available.

Advantages, – ecological and economical
Monocultures, are ecologically often seen as ‘deserts’ withonly one species, like spruceplantations or cornfields. Compared with these agroforestry offers much more biodiversity. Already hedgerows or trees as windscreens offer possibilities for birds, small mammals and insects. Also human beings are attracted by landscapes with more structure, making it valuable for recreation

Mixed systems use light, water and nutrients more efficiently. For instance: walnut trees take much light away in summer, but wintergrain growing under them has its growing season in spring, when the trees give little shadow. Often people think shadow is ban for the crops, but this is not always true. Trees protect against too much evaporation and serve as wind screen. Temperatures of air and soil under trees are higher, and bees can do their work better.

Biodiversity
Higher biodiversity also means more predators for aphids and other pests. It is also more difficult for pests to spread when trees grow between the crops. Potatoes will have more problems with fungi under trees, so it is important to choose the right crop!
In small scale landschpes more natural ennemies of the pests (birds, ichneumons) will be able to survive.
Water- and wind erosion is less under trees
In general we can expect that prices of hardwood will rise in the future, because of growing need and shrinking production (disappearing tropical forests). And the need for biofuel will grow too. Trees can produce many things, not only wood, but flowers – and honey from them, fruits, medicins. Moreover they give services to the society that can not be counted in money like protection, from hard winds, from erosion, fixing atmosferic nitrogen, producing biomassa, restore polluted soils etc.

Higher production
The production of these mixed systems is often higher than in separate monocultures. 1 hectare agroforestry can produce as much as 0,8 ha cornplus 0,5 ha forest, 1,3 LER (=Land Equivalent Ratio), this is the unit of production in monocultures. Example: radishes in a pear orchard produced 1.65 LER economically and even 2.0 in biomass.

Fruitproducers in Ontario (Canada) are used to growvegetables under their fruittrees when planting a new orchard. They can sell products whiloe the trees are growing, and even the fruit production increases because the trees are forced to make deeper roots, and can stand droughts and frost better for this reason
Cattle under trees has less problems with cold or heat.
Agroforestry farms are more attractive for tourists etc
There are many good reasons to develop agroforestry. One big problem is the system of subsidies: farmes can get subsidies for forestry or for agriculture, but not for the combination
Europe should change – or stop the system of subsidies. Than agroforestry would certainly grow!

Agroforestry in Burkina Faso : Sorghum under the trees: Faidherbia albida and Borassus akeassii

Agroforestry can help saving the rainforests
Also in the tropics agroforestry gives many possibilities, plantation of coffee with big shadowy trees are already normal.
But much more is possible. Farmers can have the possibility to have crops ready for the market through the year like partly forest, combined with organically grown frui trees, rubbertrees, beans, maniok (cassave) and sugarcane in one farm in Amazonia. In this way some of the characteristics of the forest can be preserved: intensive production, and protection against erosion and drought

Sources:
www.wervel.be/agroforestry and others
.

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Sustainable Footprint

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