Anthropogenic forests in the Amazon

The Walden Effect: Farming, simple living, permaculture, and invention.

Anthropogenic forests in the Amazon

The Amazonian forest is considered by many environmentalists to be the Holy Grail of untouched biodiversity. Or it was, until recently when scientists started uncovering evidence that anywhere from 8% to 100% of the Amazon forest is anthropogenic.

Slash and burn agriculture is currently the norm in the Amazon basin, and for a long time scientists assumed that slash and burn was the ancient method of managing the forest. In this technique, farmers hack a small opening out of the forest, burn the fallen trees, then plant crops in the resultant rich bed of ash. After a few years, trees begin to grow up in the gap, and farmers move on to cultivate a new area. Although slash and burn is harmful to the air, the method is vastly superior to trying to till the poor soil, which would ruin the land in less than a decade. Instead, slash and burn seems to be marginally sustainable.

The slash and burn technique, though, is clearly dependent on the European introduction of metal axes. Using the Amazonians' indigenous stone axes, scientists estimate it would have taken about three weeks to chop down a single tree. Creating a forest gap in this scenario must have been a long term undertaking with long term rewards.

Scientists are now beginning to understand that slash and burn was merely a method that Indians resorted to after disease devastated their populations. Previously, the Amazonians did hack gaps out of the forest canopy, but into each gap they planted small food crops like manioc between carefully selected tree species. The trees were the real crop, with the manioc being a secondary addition to their diet. Over one hundred carefully bred tree species now dot the Amazonian forest with their edible fruit. In essence, the Amazonians were creating a forest garden.