The prospect of change

Abstract

The ability to adapt has allowed plants to survive in all but the most hostile of environments, and the broad vegetation patterns represented by the major biomes reflect the diversity of habitat conditions which have controlled this evolutionary process. Natural ecosystems are highly dynamic and evolve in response to environmental stimuli, but whereas in the past this process was conditioned only by natural causes, humans and their technology are now important agents of biogeographic change. The world’s population increased from about 3.6 billion in 1970 to 5.5 billion in 1992 and is expected to reach 6 billion by 1998, perhaps rising to 11.6 billion by 2150 (Tolba and El-Kholy, 1992). Population growth has been accompanied by the development of mechanized agriculture and urban-industrial societies. This has greatly increased the demand for natural resources and created the problem of undesirable wastes. However, the relationship between population growth, resource development and the state of the environment varies regionally.