All the vegetation in the patch chosen is slashed and burnt. After this the area is cultivated for one or a few years and then abandoned for another forested patch.
The ash from the burned vegetation helps fertilize the soil.
Slash and burn requires a large region, as the recovery of forest may take decades. One of the side effects is erosion. Slash and burn has been used in different regions from the coniferous forests of Northern Europe to the tropical rainforests of Indochina and the Amazon Rainforest.
Slash and burn agriculture is sometimes denounced as ecologically destructive, but it is not so when practiced by small populations in large forests, where fields have sufficent time to recover before again being slashed, burned, and cultivated. Problems with ecological unsustainability can arise with significant increases of population, leading to increased pressure on the land and failure to let fields lie fallow for enough time, as has been seen in the late 20th century in parts of the rainforests of Mexico and Brazil.
See also: Milpa