This system is sensitive for any disturbance. The rain forest is part of the Amazone rain forest with some 1000 different kind of trees. About 8000 years ago men as hunters, food collectors did contribute to this eco system. Later on men began with some primitive agriculture. The garden plots began about 3000 years ago and now some tree varieties which needed light to mature had a chance.
Examples are the kankantri and kopi.
Trees with edible fruits also appeared at more places. The secondary forest can be distinguished from the primary forest especially from the air. Bamboo bushes are an example where men once started a garden plot. Other examples where men changed the primary forest are the Cordon pad also because of excavations along the path. Gold prospectors also changed the forest.