- What is the Intermediate Disturbance Hypothesis and how does it relate to management practices?

The IDH shows us that diversity is maximized in areas with intermediate disturbance. By “disturbance” we mean any phenomenon that causes change in the environment like, for example, a heavy storm, a lightning strike that starts a fire, or a large tree that falls, opening a clearing in the underbrush. If the disturbance is very large, intense or frequent, the damage to biodiversity will of course have the same proportions. On the other hand, if there are no disturbances (as in the case of complete preservation), there will also be little diversity.

Intermediate disturbances are fundamental for letting light in and renovating the forest. They allow species to coexist that have different needs for the resources. This doesn’t happen in extreme cases with much or very little disturbance. When a tree falls and opens a clearing, for example, species that need more heat and light tend to be favored, as well as their coexistence with other species. It is in assuming the existence of these changes and their importance to diversity that management is established. The role of research and scientific knowledge is to perceive the nuances of this dynamic and the ways in which human intervention can get forest products, including wood, at a rate of disturbance that is in accordance with what would happen naturally and in a way that favors ecosystems instead of harming them.

The disturbances caused by the indigenous peoples, mainly through itinerant agriculture, were important in creating varied landscapes that resulted in the abundant diversity we know today. Indigenous management of the soil resulted in extraordinary improvements in its quality as can still be seen today in anthropogenic soil in Amazonia. The extremely fertile so-called “black Indian soil,” for example, is a legacy of ancient indigenous peoples who used their knowledge to enrich the soil over the millennia.

- What do you think of strategies and policies that ignore the importance of traditional populations’ knowledge as part of biodiversity conservation?

They are derived from minds that never lived inside Amazonia or that are unfamiliar with its ecological history, its workings and the essential nature of the forest. Today’s natives, who have been in the forest for a long time, hold knowledge about the best uses for each species, about which fruits are or are not edible and what is the best season for their harvest, the best woods for each use. And they know all this in great detail.