The Importance of Ecology
Humans are dependent on their environment, as are all other organisms. Any change in the environment even in distant parts of the planet affects living things and their environment elsewhere. All organisms are dependant on each other in many ways. Destruction of one organism in the environment can lead to the destruction of other organisms. The human environment includes the entire earth and may some day include other planets as well. Technological advances have given humans the ability to exert great influence over the environment of all living things. For this reason, it is necessary to have an understanding of ecology in order to survive.
Applied ecology is concerned with the practical applications of the theories of ecology. Among the many applications of ecology are those used in agriculture and medicine. Scientific study of the relations of organisms with their environments helps farmers grow crops in the right soils and climates; provide livestock with suitable food and shelter; eliminate harmful pests; and breed new varieties of plants and animals. Ecological knowledge helps in the fight against disease. For example, knowledge of the malarial mosquito's environmental niche makes it possible to help control malaria by draining the swamps in which the mosquitoes breed.
However, in their efforts to improve the environment humans often make mistakes through lack of ecological understanding. A notable example of an ecological catastrophe caused by seemingly beneficial human intervention in natural processes occurred in Borneo shortly after World War II. A program was undertaken there to control mosquitoes by spraying with DDT. The number of mosquitoes declined drastically, but the roofs of houses began to collapse because they were being eaten by caterpillars. The caterpillars had previously been held under control by certain predatory wasps—which had been killed off by the DDT.
In addition to spraying for mosquitoes, the villagers also sprayed inside their homes to kill flies. Previously, the houseflies had been more or less controlled by lizards called geckos. As the geckos continued eating houseflies, now laden with DDT, the geckos began to die. The dead or dying geckos were eaten by house cats. The cats, which were at the end of the food chain, also began to die from the DDT concentrated in the bodies of the geckos they were eating. So many cats died that rats began invading the houses, eating the villagers' food. The rats multiplied and eventually became potential plague carriers.
Another example of ecological imbalance caused by human manipulation of the natural environment involves the Kaibab Plateau in Arizona, where Indians used to hunt deer for meat and skins. The plateau was designated as the Grand Canyon National Game Preserve in 1906. Public hunting was discontinued and hunters were hired by the government to kill off the deer's natural predators, such as wolves, coyotes, and cougars.
Subsequently the deer population rose from about 4,000 to about 100,000. The vegetation of the plateau that the deer normally fed on was not enough to sustain such a huge deer population. Not only was the plateau stripped of its vegetation, but many deer died of starvation. In order to stabilize the deer population and restore ecological balance, predators were reintroduced and public hunting was reinstated.
Humans have destroyed wildlife habitats in order to build cities, homes, factories, and highways. They have contaminated the environment with such technological products and by-products as pesticides, motor exhaust fumes, industrial wastes, and radioactive fallout. Nonrenewable resources such as fossil fuels are being consumed very fast, and their by-products cause pollution. As a result, the environment has been changed in ways that could eventually make the earth uninhabitable. Because of such problems, increasing attention is being paid to the study of ecology in schools, governments, and by interested groups elsewhere. By understanding ecology, people can take steps to reduce pollution, deforestation, and other negative fallouts of human activity, and the human cost associated with them.