For thousands of years, and continuing today, native peoples of the Amazon basin have practiced traditional shifting cultivation, which combines farming with forested habitats. Shifting cultivation, sometimes called swidden or slash and burn, is commonly found throughout the Amazon and other tropical regions worldwide. Shifting cultivation systems are designed to adapt to the soil and climatic characteristics of the Amazon basin- low soil fertility, high precipitation, and fast leaching of nutrients.
To begin the process, small clearings are cut in the rainforest and slash material is left to decompose or is burned to release nutrients into the soil. In some cases, soil fertility is augmented by fertilizers such as the terra preta of organic material, fish bones, and biochar. A mix of palms such as acai (Euturpe oleaceae) or Bactris guisapeas or pioneer fruit trees such as avocado, guava, or guaba (Inga spp.) are planted, and annual crops such as cassava, plantains, corn, sweet potatoes are cultivated in the first few years. Because of the nutrient limitations, cultivation of these annual crops is often limited to just a few cycles. After this, the farm plot will be allowed to succeed into a perennial crop or “forest garden” type of landscape, with shade tolerant perennial crops such as coffee, cacao, and other fruit trees, or long lived useful species such as rubber and Brazil nut can be harvested for many years to come. In many cases, farmers will return to these forest gardens after several decades to clear and cultivate again.
For native peoples that practice shifting cultivation, hunting contributes protein and is an important cultural activity. Overall, hunting pressure in the Amazon basin is much less than in African rainforests, as human populations are much lower and animal species are smaller. However, many species of ground bird such as the curassow, wooly monkey, howler, and spider monkeys, peccaries, and tapirs are often overhunted. Many forest species are sold in local markets, and wildlife populations are exacerbated by increased roads and mining activity. Pet species such as macaws and other parrots are also threatened by over-collection.
Other researchers contend that intensive indigenous land use may have been more restricted to rivers and that interior forest areas were lightly impacted.
Nevertheless, with small human populations and large forested landscapes, shifting cultivation is a sustainable forest use that has persisted for thousands of years. Cleared plots are small and agricultural activity is limited to a few years, so abandoned plots quickly revert to forest as soil disturbance is minimal and seed sources are nearby, even after burning. Early pioneer trees throughout the Amazon basin are species of Vismia, Cecropia, and the Melastomataceae family. Many light demanding timber species such as mahogany and Spanish cedar also use light from clearings in shifting cultivation. Scientists also find rich animal diversity in areas under indigenous shifting cultivation; a study by Yale F&ES graduate German Andrade in the Colombian Amazon found bird diversity richness similar between primary forest and secondary forest from shifting cultivation; bird species composition was similar after the secondary forest reached 10-20 years after abandonmen.
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