|Indigenous Agroforestry in Latin America: a Blueprint for Sustainable Agriculture? (NRI, 1994, 24 p.)|
Amerindians have practiced their traditional forms of agroforestry for millennia without apparent detriment to the rainforest. These systems are generally referred to as swidden agriculture, or sometimes as slash and burn or bush fallow farming (Warner, 1991). A parcel of forest (swidden plot) is cut and the area burned to release nutrients. A mixture of short-term and annual crops, often followed by perennials, are grown until soil fertility becomes inadequate to maintain production and/or competition from successional plant species becomes too great. The farmer then prepares a new site while the old field returns to fallow. During the fallow period large quantities of nutrients are stored in the plant biomass and are released during the burning of the fallow vegetation or secondary forest when the land is cleared for the new cropping cycle.
A random generation of tree species during the fallow period may not be as common as was once thought. The indigenous inhabitants of the Amazon Basin deliberately retain economically useful species during the clearing of swidden plots. These species are protected from fire and contribute not only directly to subsistence but also shape the species content of the following succession.
Pollarding may take place to leave trunks for cultivated climbing plants and coppicing is also carried out. In many cases seeds of useful trees are planted. These include both wild and semi-domesticated plants, which contribute to a more rapid and species-rich regeneration of the forest during the fallow period.
When the annual or semi-perennial crops have ceased production during the second or third year, management of the swidden plot is reduced to occasional weeding around useful trees. However, the plot may produce valuable products for up to 25-30 years. After this time the field may be cut and burnt once more or be out-competed by high forest.
There are several common elements associated with these indigenous agroforestry systems in Latin America (Alcorn, 1990). Firstly, fallows are seen as a useful phase in the productive process and not only as a solution to declining fertility, weed and pest problems. Farmers incorporate native species into their managed fallows; species which often occur naturally in primary or secondary forest and chosen for their multiple uses.
Secondly, farmers take the best advantage of natural environmental variation. They recognize numerous ecological zones, soil types and topographical units which they use for different species according to the needs of each.
Thirdly, farmers control pests and avoid risk by enhancing diversity; a variety of native and exotic tree and crop species are introduced into the field.
This diversity also enables households to meet subsistence needs, and it encourages experimentation and change within the system as positive crop associations develop spontaneously within communities. Thus traditional farming strategies are not only flexible, responding to changing household circumstances, they are also dynamic, with new species being introduced to the system along with the possibility of increasing production for the market.
Finally, forest is only cleared in discrete parcels allowing the natural (or species-enhanced) forest to eventually regrow. Here we have the basis of a sustainable system, not a destructive one.
The literature contains many descriptions of indigenous swidden agriculture in the Amazon Basin. In the next section four case studies are used to highlight their common features.