Rangeland

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Rangeland

Rangeland is uncultivated land that is suitable for grazing and browsing animals, and is one of the major types of land in the world. (Other types are: forest, desert, farmland, pasture, and urban/industrial.) Rangelands are the principal source of forage for livestock and they also provide habitat for a variety of native plants and animals. Rangelands are also used for recreation. Some plantspecies of rangelands are used in landscaping, and as sources of industrial chemicals, pharmaceuticals, and charcoal.

Generally, rangeland is not fertilized, seeded, irrigated, or harvested with machines. Rangelands differ in this respect from pasturelands, which require periodic cultivation to maintain introduced (non-native) species of forage plants. Pasturelands may also need irrigation or fertilization, and they are usually fenced. Rangelands were originally open natural spaces, but much of their area has now been fenced to accommodate livestock grazing. In addition, livestock grazing often utilizes rotation systems that require partitioning.

Rangelands were distinguished at the turn of the century by their native vegetation. Today, however, many rangelands support stands of introduced forage species that do not require cultivation.

Types of rangeland

Rangelands support plant communities that are dominated by species of perennial grasses, grass-like plants (or graminoids), forbs (non-graminoid, dicotyledonous plants), and shrubs. There are five basic types of rangelands worldwide: natural grassland, desert shrubland, savanna woodland, forest, and tundra. Grasslands do not have shrubs or trees growing on them. Desert shrublands are the most extensive and driest of the rangelands. Savanna woodlands are a transition between grasslands and forests, and contain herbaceous plants interspersed among scattered, low-growing shrubs and trees. Forests contain taller trees growing closer together than in savanna. Tundra areas are treeless, level plains in the Arctic or at high elevations of mountains.

North American rangelands consist of: (1) the prairie grasslands of the midwestern United States and Canada, as well as parts of California and the northwestern states; (2) cold desert rangeland in the Great Basin of the United States, and hot desert (Mojave, Sonoran, and Chihuahuan) of the southwestern United States and northern Mexico; (3) open woodlands from Washington state to Chiuhuahua, Mexico, and in the Rocky and Sierra-Cascade Mountains; (4) forests (western and northern coniferous, southern pine, and eastern deciduous); and (5) alpine tundra (mostly in Alaska, Colorado, and western Canada) and arctic tundra (in Alaska and northern Canada).

There are more than 283 million hectares of natural range ecosystems in the United States. However, much of the United States prairie grasslands have been converted to agricultural land-use. In addition, excessive grazing and fire suppression have allowed the invasion of prairie by species of woody plants, such as mesquite, in some regions.

Range management

The first principles of scientific range management were established by research in North America during the 1890s, and by grazing system experiments in the early 1900s. Variations of many of these practices, such as grazing rotations, had been used by pastoral herders in Asia and Africa for centuries.

Grasses of the semi-arid plains provide an excellent winter forage for livestock. Unlike their eastern counterparts, which tend to fall to the ground in winter and rot, prairie grasses cure while standing and do not have to be harvested, baled, or stored for winter use. However, if they are grazed intensively throughout the summer and autumn, prairie grasses cannot produce an adequate crop of winter forage.

Good rangeland management recognizes that perennial grasses must have sufficient time for their

KEY TERMS

Climax community— A community of plants and animals that persists in the presence of stable, ambient conditions, particularly climate.

Forage— Vegetation that is suitable for grazing animals.

Forb— A perennial, herbaceous, broad-leafed (or dicotyledonous) plant.

Grassland— A type of rangeland that is usually free of shrubs and trees. Grasslands most commonly occur on flat, inland areas at lower elevations.

Pasture— Rangeland that is dominated by introduced species of forage plants, and that requires periodic cultivation for maintenance.

above-ground biomass to regenerate after grazing; otherwise the plants become overgrazed, and may not survive. A healthy population of native grasses helps to prevent invasion by non-native plants, some of which are unpalatable or even poisonous to livestock. Severe overgrazing removes too many plants of all types from an area, causing a loss of soil moisture and fertility, and increasing erosion. Range managers have learned that for the long-term health of rangelands, they cannot overstock or overgraze them with cattle or other livestock. In spite of this knowledge, excessive use of rangelands remains an important problem in most parts of the world, including North America.