Much of the composition of the present rainforest, too, is probably anthropogenic (caused by human activity), although we think of it as pristine. Approximately 12% of the Amazon rainforest may have been altered by humans through prey selection, seed dispersal, and plant domestication. The vegetation of many rainforest areas has also been determined by centuries of slash-and-burn (“swidden”) agriculture, leading to a forest mosaic consisting of many stages of forest succession, interspersed with areas of climax (mature) forest. Humans also altered forests through the use of fire for hunting, for fuel, and other purposes. The presence in eastern Amazonia of plants useful to humans, such as palms of the genus Astrocaryum, is thought by some to indicate that humans had originally planted these species. Therefore, some feel that the composition of many present-day forests is the result of enrichment or alteration by human agriculture and occupation (Mann, 2000). This type of evidence for human occupation is disputed by many, however. (For discussions of the presence of ancient man in rainforests, see, for example, Bray, 2000; Mann, 2000; Pope, et al., 2001; Piperno, et al., 2000; Butzer, 1999; Denevan, 1992.)

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