If more animals are put on the land than the land can sustain, then the animal suffer from malnutrition. In extreme cases, the land loses its' protective cover of plants and erosion starts. The battle for survival and dominance by plants on the rangeland and the resulting change in the kinds and amounts of plants that exist is called ecological succession. Ecological succession can be advance or retarded by the action of man. Non-use can lead to low vigor.
Proper use keeps land healthy, while overuse deteriorates the resource.
Fire was an important component in keeping the brush from overpopulating rangelands and keeping the grasses in a healthy state. Plants are influenced by soil types which compose ecological sites. Locate an area where this is evident. For instance, post oak grows on shallow soils, grasses grow on prairie soils. These are different soils and ecological sites.