Conservation

I

Introduction

Conservation, sustainable use of natural resources, such as soils, water, plants, animals, and minerals. In economic terms, the natural resources of any area constitute its basic capital, and wasteful use of those resources constitutes an economic loss. From the aesthetic and moral viewpoint, conservation also includes the maintenance of national parks, wilderness areas, historic sites, and wildlife. In certain cases, conservation may imply the protection of a natural environment from any human economic activity.

Natural resources are of two main types, renewable and non-renewable. Renewable resources include wildlife and natural vegetation of all kinds. The soil itself can be considered a renewable resource, although severe damage is difficult to repair because of the slow rate of soil-forming processes. The natural drainage of waters from the watershed of a region can be maintained indefinitely by careful management of vegetation and soils, and the quality of water can be controlled through pollution control. See Air Pollution; Environment; Reclamation; Sewage Disposal; Water Pollution; Energy Conservation.

Non-renewable resources are those that cannot be replaced or that can be replaced only over extremely long periods of time. Such resources include the fossil fuels (coal, petroleum, and natural gas) and the metallic and other ores. For discussions of conservation problems in this area, see individual entries on the substances concerned.

II

History

Although the conservation of natural resources has been recognized as desirable by many peoples since ancient times, frequently the basic principles of sound land use have been ignored, with disastrous results. Major losses—for example, the silting of rivers and the flooding of lowlands—resulted from the destruction of the forests and grasslands that protected watersheds in northern China and the Tigris-Euphrates area. Large areas in North Africa and the Middle East were rendered barren by centuries of uncontrolled livestock grazing, unwise cultivation, and excessive cutting of woody plants for fuel. Similar damage has also occurred in most of the more recently developed regions of the world, sometimes through the unwise introduction of species into new environments. The increasing industrialization of nations around the world continues to present severe conservation problems although international cooperation efforts have also evolved in certain areas, such as the protection of some endangered species. Some basic conservation principles in major areas of concern are discussed below.

III

Forest Conservation

In forests more than any other ecosystem, demand is increasingly being made that conservation should involve preservation from any destructive commercial use, particularly the cutting of trees for timber, which in a virgin forest is known to have harmful consequences far beyond the loss of the actual trees (for example the loss of animal habitats, and soil erosion). Where tracts of virgin forest are given over to timber production, principles of management have evolved in order to minimize the destructiveness of the process and to make it as sustainable as possible. The management of forest trees for timber production involves three fundamental principles. The first is protection of the growing trees from fire, insects, and disease. However, fire, once regarded as a destroyer of forests, is now recognized as a management tool when carefully employed. Some important timber trees actually require fire for successful regeneration. Insects, such as the gypsy moth, spruce budworm, and pine sawfly, and disease, still take a heavy toll. However, biological control measures and some aerial spraying, proper cutting cycles, and slash disposal are increasingly effective. The second principle concerns proper harvesting methods, ranging from removal of all trees (clear-cutting) to removal of selected mature trees (selection cutting), and provision for reproduction, either naturally from seed trees or artificially by planting. The rate and frequency of any cutting should aim for sustained production over an indefinite period. The third principle of timber management is complete use of all trees harvested. Technological advances, such as particleboard and gluing, have created uses for branches, defective logs, trees too small to be milled into boards, and so-called inferior trees. As demand for wilderness areas and recreational use of forests increases, management of commercial forests will become more intense. See Forest; Forest Fires; Forest Conservation and Management.

IV

Conservation of Grazing Lands

One of the principles of range conservation is the use of only a portion (usually about a half) of the annual forage-plant production of a particular range in order to maintain healthy plant growth and reproduction. In addition, each range is stocked with the number of animals that can be nourished properly on the available usable forage and are permitted to graze only during the season suitable for that type of range. The conservation of ranges is based on a programme of grazing designed to keep them productive indefinitely and to improve depleted areas by natural reproduction or by artificial seeding with appropriate forage species. Although these principles are well established, many hundreds of thousands of acres of public grazing lands are still overgrazed.