n a fragmented state in nature, with subpopulations scattered around an area," Vandermeer said. Disease or predators may wipe out a particular subpopulation, but migrants from nearby subpopulations come in and establish a new subpopulation. "We now think that most high diversity situations operate this way, with a continual process of local extinction and re-migration. When you couple that ecological theory with the observation of highly fragmented forests in the Atlantic coast rainforest, the real question is not how much forest is left, but what's between those patches that are left, and will it support the necessary migrations from patch to patch as local extinctions occur, which they inevitably do?"

If forest patches are separated by barren pastures or fields of single crops, such as soybeans, then monkeys, birds, and other forest animals probably won't travel through them to repopulate areas where extinction has occurred. But that's not the case if the intervening areas are traditional "agroforests"---farms where fruit and timber trees share space with other crops, Vandermeer said. "That's the kind of agriculture that's friendly to biodiversity, and that's the kind of agriculture that peasant farmers actually do."

Vandermeer and Perfecto, a professor of natural resources and environment, visited agroforests in the Pontal de Paranapanema region of Brazil, where landless peasants organized by Catholic priests established homesteads in the 1950s and 1960s. There, the researchers saw evidence that the farms do indeed serve as thoroughfares for migrating animals. "These farmers actually have monkeys that come through their farms," Vandermeer said.

The U-M scientists and their collaborator Jefferson Ferreira Lima of Brazil's Instituto de Pesquisas Ecologicas also spoke with members of the Landless Workers' Movement (Movimento dos Trabalhadores Rurais Sem Terra, or MST), which is a member of the international peasant organization Via Cam
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Contact: Nancy Ross-Flanigan
rossflan@umich.edu
734-647-1853
University of Michigan
8-Aug-2006

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