Environmentally-displaced peoples and the cascade effect: lessons from Tanzania.

Abstract

This paper investigates the links between migration and ecological change by focusing on environmentally-displaced populations. The discussion is based on a case study from the Usangu Plains, Tanzania, a receiving area for displaced herders and cultivators from elsewhere in Tanzania. I focus on two of these groups—the Nyakyusa and the Sukuma—in analyzing the ecological causes and consequences of rural–rural migration. The spread of cash crop production, leading to degradation and resource scarcity, was a key factor underlying displacement from both locations. I emphasize social and cultural variables influencing resource use and management in assessing the ecological impact of migration on the Usangu Plains. Migration is not always ecologically destructive; this paper indicates some of the conditions under which it can have this outcome. In this case study, environmental displacement caused environmental problems to be transferred elsewhere, to be translated into new forms, and to increase in complexity, a phenomenon I call the “cascade effect.”