Human Impact on Biodiversity: Consequences for Ecosystems and Humans in Latin America and Africa

A Lecture by Rodolfo Dirzo
Tuesday, May 15, 2012 - 12:15pm

Bechtel International Center, Assembly Room

Rodolfo Dirzo, CLAS Director and Bing Professor in Environmental Sciences, Stanford University

Two common features of Africa and Latin America are their exuberant biodiversity and the dramatic negative impact of human activities on the two regions’ ecosystems. With the exception of the arid lands of the two continents, their more equatorial (tropical) and temperate ecosystems hold a significant proportion of the world’s biological diversity. At the same time, habitat destruction, as revealed by satellite imagery and calculation of the corresponding deforestation rates, is in some regions of the two regions among the highest worldwide. Beyond deforestation, recent research has uncovered the fact that human impact on wildlife, a phenomenon that, by analogy, I call “defaunation,” although not readily visible, is also of dramatic magnitude, in some cases leading to a syndrome of “empty forests” or “empty savannahs” in many parts of both continents. In this talk I will try to i) illustrate the nature and magnitude of defaunation, and ii) ask the question: what are the possible consequences of such defaunation? I explore this question from an ecological perspective –disruption of some ecosystem processes– and then consider the possible ramifications of these ecological disruptions in terms of risks to human health. While I have researched the former – ecological consequences– largely in Latin America, our recent work, exploring risks to human health, is being conducted largely in East Africa. I will share pictures and some data that, albeit preliminary, strongly suggest that animals are much more than a splendid decoration of Neotropical forests and African savannahs.


adorialaatstanford [dot] edu