CONSERVATION OF GRAZING LANDS

Grazing lands also called ranges, are grass-covered areas too dry to support farms or forests. These lands provide homes for many wild animals, including pronghorns and mule deer. Numerous grasses and such flowering plants as goldenrods and sunflowers grow there. Ranges also provide pasture for cattle, horses, and sheep. Some of the world's largest grazing lands lie in western North America, southern South America, and Australia. The chief conservation problem on ranges is overgrazing, which results when too many animals graze an area or when the animals stay in one place too long. The grasses then die and are replaced by weeds and poisonous plants, which provide poor pasture for livestock.

Overgrazing also results in increased runoff of water, which causes soil erosion. Overgrazing also ruins wildlife habitats. For example, it often occurs on the fertile areas that border a stream. Livestock trample on stream banks and kill plant life. This results in increased erosion along the stream bank and may cause the stream to become too muddy to support fish and other aquatic life.

Grazing lands, many of which are owned by national governments, must be carefully managed to ensure a continuous supply of forage (plant food) for wildlife and for livestock. To prevent overgrazing, range conservationists must determine the carrying capacity of the land. The carrying capacity is the largest number of animals that an area of land can support without destruction of plant life. Range conservationists limit the number of livestock on a range so that the carrying capacity is not exceeded. Livestock managers must move the herds from time to time so that the grasses can regrow.

To improve the vegetation on grazed lands, range managers sometimes practice prescribed burning. That is, they set fires to help control brush and poisonous plants. When properly controlled, such burning will not harm native plants. Many of these native plants have become adapted to surviving, and even flourishing, in areas with frequent, low-intensity fires.