|Indigenous Agroforestry in Latin America: a Blueprint for Sustainable Agriculture? (NRI, 1994, 24 p.)|
The core beneficial elements of both the indigenous and market-orientated systems can be set out under the following headings: sustainability, productivity, biodiversity, soil conservation, flexibility, population density and use of native species.
These case studies show that agroforestry systems used by the indigenous people are both productive and potentially sustainable; forest is only cleared in discreet parcels and can easily regrow. Production is sustained by use of species-enhanced long-term fallows and biomass recycling. The systems even contribute to biodiversity and soil conservation. In their flexible use of locally adapted, as well as exotic species, they can respond to new conditions and in doing so can support high population densities. It is now clear that Amerindians make good use of the natural resources available to them, both in terms of production for subsistence, and sustainability. They have a sophisticated understanding of their environment, its micro-variations, and its potential for crops (Clay, 1988; Hecht, 1989).
Hecht (1990) has compared three types of land use system in the eastern Amazon. Short cycle new colonist slash and burn systems and pasture/ ranches were contrasted with the Kayapo indigenous system (see Case 2). Kayapo yields (edible harvest) over a period of five years were roughly 200% higher than new colonist systems and 175 times that of livestock production systems. New colonist agriculture rarely continues beyond five years as the soil is exhausted of nutrients for annual cropping. Therefore a comparison between Kayapo and new colonist agriculture over a ten year period is not possible. However, Kayapo and livestock comparisons reveal that animal production is a mere 700 kg of beef compared with 84 t of crops from the indigenous system. Not only is the indigenous system more productive than modern forms of agriculture but it is also less environmentally damaging and more sustainable.
Balee (1989) and others have argued that Amerindians have manipulated natural resources so much, by the interchange of useful plant species between ethnic groups, that they have transformed much of Amazonia, and thereby increased biological diversity throughout the region. Balee estimates that 12% of non-flooding forest is of cultural origin and that useful species such as the Brazil nut are much more abundant than they would have been without the intervention of indigenous cultures. Long-fallow swidden cultivation recreates the diversity, complexity and use of biomass for nutrients that existed in natural forest (Warner, 1991). Swidden cultivators actively recreate the forest in their fields, selectively protecting useful species, so as to preserve long-term stability and production. Thus the local biology is disturbed as little as possible and its periodic re-establishment ensures useful future production of plant materials and game. Diversity exists in varieties, crops and the number and type of swiddens cultivated, which reduces risk, maximizes options and guarantees household subsistence.
Not only do indigenous societies possess technical knowledge concerning the suitability of soil types for cropping but it is argued that their soil management is superior to new colonist and large-scale livestock production (Hecht, 1989; Unruh, 1988; 1990). There is less destruction of the nutrient cycling root mat in the swidden cycle, as coppicing and the selective protection of valuable species is practiced. Therefore, the root mat quickly re-establishes itself during the fallow cycle. Useful standing trees in new swiddens protect the soil from the effects of excessive insolation and precipitation and also protect naturally occurring seeds from the initial burn, thereby encouraging a faster regeneration.
Traditional swidden systems are not static; new varieties of plants are incorporated as they become available. For example, valuable timber tree species have been introduced to forest fallows by the Bora of Peru (Denevan et al., 1984). Maize, plantains and rice are relatively recent introductions (Warner, 1991), although cassava remains the staple in the Amazon region. These new introductions have expanded the diversity of the system and may have improved food security and resulted in higher productivity (Alcorn, 1990).
Although swidden cultivation is generally practiced in areas of low population density (with the exception of the Huastec of Mexico), this is not necessarily a reflection of the carrying capacity of the land. The indigenous populations were decimated by Old World diseases from the 15th century onwards, and scattered populations were brought together by Christian missionaries.
Adapted indigenous systems in the Peruvian Amazon appear to be able to provide for household subsistence and sale to market from areas of 1.5-2.5 ha (Hiroaka, 1989); with a 10 year fallow a maximum of 25 ha is sufficient for one family. Few of the studies of indigenous swidden cultivation have measured, calculated or estimated the area required for household subsistence under this form of management. It appears that these systems require less land than colonist agriculture (50 ha in Bolivia, 50-100 ha in Brazil) mainly because fallows are enhanced and managed with useful species over as much as 30 years, which reduces dependence on annual crops for subsistence and sale.
USE OF NATIVE SPECIES
The encouragement and planting of native and semidomesticated species amongst annual and semi-perennial crops discourages the establishment of noxious weeds and grasses (e.g. Imperata spp.), whilst improving the colonization of early successional species. Crops domesticated by indigenous groups use locally available nutrients more effectively than imported cultivars (Clay, 1988). Managed fallows have a litter-fall higher in nutrients than unmanaged fallows (Unruh, 1988). Fallow management also increases the chances of distribution of seed by frugivores which may result in the presence of more economically useful plants. Not only is soil less likely to degrade under these practices but swidden fallows produce a forest with more useful species present than undisturbed forest. Many of these useful fruit producing species in turn attract game which are harvested by indigenous communities.