Topic 3.1: Biodiversity

Tropical forests are home to most of the species of plants, animals, microbes, bacteria, and fungi on our planet.  Arguments can be made for the intrinsic rights-for-existence of each of these estimated 10 million species, but more persuasive arguments are based on the importance of many of these species for human well-being.  If we think about each species as containing an extensive library of genetic information that has been collected and refined over millions of years of evolution, then allowing even a single species to go extinct would represent the height of folly. Despite the importance of this genetic information to human welfare as sources of new drugs and as sources of gene sequences that can confer on our crops increased pest or stress resistance, we allow some 1,000 species per year to go extinct, and most of these extinctions occur in tropical forests.

The concept of “biodiversity” also includes consideration of ecosystem and landscape diversity. As is the case with diversity at the level of species and genes, tropical areas are extremely rich at these higher levels of organization. The loss of ecosystems such as the Atlantic rainforests of South America, the high elevation grasslands in Africa, the lowland dipterocarp forests of Southeast Asia, and montane forests throughout the tropics should be of as much or more concern than extinction of species. Certainly there is a great deal that we should learn about the functioning of these ecosystems before they disappear from the face of the Earth.

Foresters can contribute to the protection of biodiversity by designing silvicultural treatments to have minimal impacts on non-target species.  Providing protection for novel ecosystems (e.g., rock outcrops) and areas critical to the survival of numerous species (e.g., stream courses and other wetlands) are obvious ways to maximize biodiversity maintenance in managed forests.  Although forests managed for timber and non-timber forest products may not maintain as high a proportion of total diversity as large protected areas (that also require management!), they can be important reservoirs of diversity if they are managed with biodiversity in mind.