The wholesale conversion of tropical ecosystems today was foreshadowed a century ago on the vast grasslands of North America. The nearly 300 million hectares of tallgrass prairies that once blanketed the midwestern United States have now been reduced by farming, grazing, and the invasion of exotic plants to less than one tenth of 1 percent of their original expanse. This tiny remnant provided fertile ground for the first deliberate experiments in ecological restoration.
Wildlife ecologist Aldo Leopold conceived of prairie restoration in 1934. Leopold, then director of the University of Wisconsin Arboretum, sought to recreate the native plant communities that original settlers had encountered in Wisconsin. As he suspected, the process proved far more intricate than simply broadcasting seeds and hoping for the best. Native species have to be reintroduced in a pattern and sequence that sets natural succession in motion. The work is complicated by the presence of
tenacious alien species that have been inadvertently introduced to the United
