We are now facing widespread heatwaves, collapsing glaciers and storms of rarely observed intensity and frequency. All these phenomena are more or less direct consequences of climate change, which is itself caused by an over-accumulation of GHGs (greenhouse gases) in the atmosphere. To reduce this and capture these gases, trees, thanks to their photosynthesis, represent an effective strategy for capturing CO2, one of the main greenhouse gases.
However, despite these challenges, between 13 and 15 million hectares of forest are still disappearing every year. 80% of this deforestation is directly attributable to agriculture; this is due to an ever-increasing need for agricultural land, driven by a growing population, which is expected to reach at least 9.5 billion by 2050. So how can we continue to feed ourselves without damaging our forests? Let's see how agroforestry can help.
What are the principles of agroforestry?
This is a method of agricultural production that combines tree plantations with other crops on the same plot.
The objective of this combination is to allow the species to help each other and to take advantage of their respective strengths. A system of differentiated "layers", called strata, allows species to help each other both above and below ground. Trees, spaced further apart, have more room to develop their branches and roots. Crops benefit from better recycling of nutrients thanks to the intense activity of mycorrhizae (a symbiotic association between a fungus and plant roots that allows them to absorb more water), as well as from the protection against wind, heavy rain and hail provided by the trees.
Agroforestry systems also play an important role in preventing erosion and improving soil fertility through leaf fall, which allows nitrogen fixation and deposits minerals from deeper soil layers on the surface. This combination of trees and agriculture optimises natural resources, captures CO2 and increases the overall productivity of the land.
What are the different types of agroforestry?
Agroforestry is based on universal principles; however, each farmer invents, experiments and adapts to develop optimal practices to meet his or her constraints and production objectives. Agroforestry models therefore differ according to the environment. For example, in a plantation in Latin America, trees such as cocoa, which is adapted to humid soils, will be found, whereas fig trees are more common in Mediterranean regions.
Agroforestry systems are varied and there are several types of crop associations. These include intercropping with fruit orchards (an example of combined agroforestry), plots surrounded by trees or hedges as boundaries, called bocages (an example of separate agroforestry), but also sylvopastoralism, a form of sustainable agriculture that reconciles forestry and pastoral objectives. In the latter example, the animals benefit from the shade created by the trees and the quality of the pasture, and at the same time, the soil is fertilised via the animals' offal, which generates virtuous exchanges. In addition, the various commodities produced by the agroforestry system constitute a source of income for the farmer.
What are the benefits for the farmer?
Farmers who use agroforestry systems can create complementary plant associations that are better able to protect each other and thus drastically reduce the need for fertilisers and especially pesticides. Indeed, as soon as it is planted, the tree naturally sinks its roots deeper than the crops around it. By doing so, it increases the exploitation of the soil in depth and favours the capillary rise of deep water. This allows rainfall to infiltrate the soil more easily and then recharge the water table. This makes the trees more resistant to drought and heat.
Crop productivity is increased, the use of inputs is reduced, resources are optimised and the soil is regenerated, all of which are advantages for the farmer who turns to agroforestry.
What are the environmental impacts?
Agroforestry is one of the panels of techniques available to agroecology to transform a more sustainable sustainable agriculture. Trees, in an agroforestry system, create, thanks to the optimization of photosynthesis, a carbon sink, both in their wood but also in the soil which is enriched in depth in organic in the soil, which is enriched in depth with organic matter. Other impacts to fight against erosion and salinization of soils as well as the risk of flooding.
Agroforestry also creates a strong plant and animal diversity. We can note an important faunal diversity with the arrival of pollinating insects in the crops or small mammals small mammals, crop auxiliaries and birdlife. Agroforestry plantations agroforestry plantations can thus become "biodiversity shelters" for living organisms, which in turn allow for better agricultural productivity. The agroforestry plantations can thus become "biodiversity shelters", allowing a better agricultural productivity.