Anthropogenic Factors of the Environment

changes which influence the organic world and are introduced into nature by human activity. In reworking nature and adapting it to their own needs, people influence the lives of animals and plants by altering their habitats. The influence may be indirect or direct. An indirect influence is exerted by changing landscapes—that is, the climate; the physical condition and chemical composition of the atmosphere and bodies of water; the structure of the earth’s surface, soils, and vegetation; or the animal population. The increased radioactivity produced by the development of the atomic industry, and especially by nuclear weapons tests, is a very important factor. Man consciously and unconsciously destroys or displaces some plant and animal species and widens the distribution of others or creates favorable conditions for them. He has created a substantially new environment for cultivated plants and domestic animals and has frequently increased the productivity of developed lands. However, in doing so he has made it impossible for many wild species to exist.

The increasing world population and the development of science and technology have made it very difficult to find areas untouched by human activity (for example, virgin forests, meadows, or steppes). Improper plowing and immoderate grazing of cattle have not only killed natural communities but also intensified the water and wind erosion of soils and made rivers shallower. On the other hand, the rise of settlements and cities has created favorable conditions for many animal and plant species. Industrial development did not inevitably lead to the depletion of animate life; in fact, it often helped the development of new animal and plant forms. The development of transport and other means of communi-cationpromoted the spread of both useful and injurious plant and animal species. Human influence is sometimes exerted directly on living organisms. For example, irrational fishing and hunting have sharply reduced the numbers of several species. The increasing impact and quickening pace of man-made changes in nature are making its conservation a necessity. According to V. I. Vernadskii (1944), the deliberate, conscious transformation of nature by man, with his penetration into the microworld and outer space, marks the formation of the “noosphere”—the earth’s envelope altered by man.