A Contemporary Mass Extinction: Deforestation of Tropical Rain Forests and Faunal Effects

Abstract

In order to assay the magnitude of potential extinctions resulting from the current deforestation of tropical rain forests, I compared the changes in mammalian faunas in Amazonia, Central and Western Africa, SoutheastAsia, and Madagascar to background extinction rates and mass extinctions at other times in the Cenozoic. Within 165 years human-mediated extinctions will have befallen 45% of the genera and 54% of the families within tropical forests. These taxa are mainly members of endemic and relict faunas. This contemporary event is comparable to other Cenozoic extinctions, with extinction rates much greater than the background extinction rates affecting earlier Cenozoic mammals. These comparisons are based on the following assumptions: within-habitat extinction rates are comparable to mean extinction rates from multiple-habitat ecosystems; and all threatened genera go extinct and are preserved. However, constraints on my assumptions will reduce the perceived magnitude when viewed historically. The distinctness of this extinction is questioned with reference to the Pleistocene events.