The myth of the primeval forest
The Amazon of popular imagination is probably one that is constructed by media: a flat landscape engulfed in lush greenery, tall trees entwined with climbers and creepers, fertile soils, all drained by the mighty Amazon River. This visual imagery is often accompanied with a narrative of these being primeval forests that temporally evolved in isolation from humans. Through this narrative, the nature-human dichotomy is established; one where the latter is viewed as a late interloper and harbinger of destruction. But this account overlooks the role that Indigenous populations and their practices have played in creating the biodiverse and fertile Amazon we see today.
Studies on the anthropogenic history of the rainforest say that the first Indigenous populations arrived in the region nearly 10 000 years ago. While the rainforest existed at the time of their settling, much of the species’ biodiversity and carbon sequestration abilities were enhanced as a result of their interventions. While many believe they are observing ‘natural’ forests in the Amazon, the landscape is invariably studded with evidence of human agency. Vast tracts of existing forests reflect human intercessions in plant domestication. Anthropologist Darrell Posey documented substantial amounts of forest manipulation by the Kayapó Indians with the planting of useful trees like the Piqui, Brazil nut, Maripa palm, and cacao. Fruits and nuts were consumed by them while opening new niches for native wildlife. Thus, they sustained the forest while sustaining themselves.
The paradox of infertile soils
The luxuriance of tropical forests can deceive one to think that the soil is fertile. On the contrary, they exist on soils that are, by temperate zone standards, mostly poor. The combined effect of warm temperatures and vast amounts of rainfall depletes nutrients like nitrogen, potassium, and phosphorous from the soil, making it deficient. Its acidic nature means ions of hydrogen, hydrous oxides, and aluminum occupy the pores in the soil . As a result, external fertiliser application is rendered useless because the soil cannot retain them. The richness we associate with these forests is actually bound up in the living organisms of the ecosystem – layers of leaf litter, plants, animals, and microorganisms – whose nutrients are efficiently recycled. The land management practices employed over centuries by the Indigenous communities aided in the establishment of the complex symbiotic relationship that allows for this.
Fire is no stranger to the Amazon forests. You can nearly always find evidence of charcoal if you dig a few feet into the soil, especially in the uplands. The use of burning by Indians for agricultural and forest management strategies is well-documented in anthropological literature and is evidenced by the Amazonian Dark Earths or Terra Preta. These anthropogenic black soils are associated with long-enduring Indian settlement sites. It is a by-product of charring biomass which when deposited with compost, manure, pottery, and dead biomatter formed a carbon-rich substrate which enhances these highly weathered soils.
Fire is integral to managing humid tropical forests for human purposes like agriculture; it not only adds carbon to the soil but also helps control pests and suppress weeds. So, the issue is not the use of fire itself, but how it is used.
Ecological succession in forests
Human or natural disturbances in forest areas can lead to the destruction of its vegetation. If this happens, the process of land recovery that begins is called ecological succession. Succession occurs in a predictable manner. The first generation of plants are species of herbs and grasses that are shade-intolerant and fast-growing trees. They colonise the open ground and contribute to the initial vegetation. As they grow, the conditions within the habitat change. The trees become shadier and the nutrients available in the ecosystem change. Many of the first-generation plants are unable to survive and die. As succession proceeds, the site becomes larger, home to numerous animal species which act as pollinators and establishes secondary plant species with a longer life. As the forest becomes larger and the biomass increases, the initiation of symbiotic relationships involving various microorganisms allows for nutrients that were released by the destruction of the forest to be recaptured and recycled. In this manner, the once denuded land gives way to a forest with successional vegetation of different ages and harbours a variety of fauna.
There is inherent vulnerability in the use of fire to overcome the forest’s fertility constraints. The destruction impairs the means of nutrient cycling and there is a risk of the fertility elements being flushed away if the mechanisms of succession are thwarted. If new plants efficient in taking up the nutrients are not in place, what remains is not just a degraded ecosystem, but also one which no longer can recover biologically.
Contrary to the destructive burning practices employed by the colonists of the Amazon today, the way the native tribes used it stimulated forest succession. Fire was coupled with activities that compensate for the destruction. This in turn enhanced diversity and nutrient recapture, thus regenerating forests.
Indigenous fire practices of the Kayapó Indians
In April/May, the dry season begins in the Amazon. This is when forests are cut and logs are left to dry until August/September, when the fires are set. Kayapó shamans who oversee the process of burning are skilled in fire management. Fire being integral to Indigenous cosmology, their traditional knowledge covers a complex taxonomy of fire: when to use it, how to attain a desired degree of heat, how to master it, and how it can be used to produce a desired quality of ash, the uses of which are not only agricultural, but also medicinal and ritual. Prior to burning, the plot is planted with varieties of sweet potato, manioc, and yam. These begin to sprout as soon as the fires have cooled down, thus initiating agricultural succession. This is followed by short-cycle crops like corn, beans, and squash along with longer-cycle crops like perennials which will be ready to harvest anywhere between six months and two years. This selection of short-cycle, light-tolerant species that give way to woody fruits ensure that the principles of succession are maintained. In the secondary successional stages, shrubs and trees which provide fruits of interest to wildlife are planted, making it an animal garden. There are other fires that are set within subplots and ashes redistributed to create hot spots of fertility. Untangling the complex science behind that will require another article in itself. But it is clear that through the combination of their actions of weeding out some plants, protecting others, selecting particularly valuable trees and shrubs, transplanting, pruning, and fertilising with bones, ashes, and mulch, they enhance the regeneration process and create plots with a large diversity of wildlife and game. Even when the tribes move to a new piece of land, the one they leave behind is anything but abandoned.
The way the Kayapó Indians manipulate the fallows can be interpreted within the terms of “First World” science. They are accomplished environmental scientists who have made immense contributions in shaping the landscape of the Amazon and continue to be active in protecting and defending their natural world. Relinquishing power to Indigenous communities and decentralising the management of the Amazon are crucial to calming the chaos that rages today in the largest rainforest on Earth.
Navya Miriam Itty, 26, Master’s in Environmental Sciences, is grateful for inspiring scholars like Susanna Hecht, whose seminal book – The Fate of the Forests – this article is mostly based on and heavily references.