Perennial Grass Composition as an Indicator of Condition of Southwestern Mixed Grass Ranges

Canfield, R

The purpose of this article is twofold: 1. To present data regarding the floristic composition of perennial grass population as indicators of range recovery and range deterioration on mixed grass ranges of southern Arizona. 2. To portray the characteristic perennial grass patterns resulting from different grazing treatments on two specific range types on the Santa Rita Experimental Range in order to aid in the recognition of similar relationships on comparable ranges. Summary: 1. Composition of the perennial grass population of mesa and foothill types of semidesert grassland range varies significantly with the general intensity of grazing to which they are commonly subjected. Grasses bear the brunt of grazing in grassland types, and therefore change more quickly than their less palatable associates. Thus the grasses record the history of past grazing use and become indicators of range condition. 2. Utilization of grasses as indicators in the management of semidesert grassland ranges has its chief value in the fact that this sort of information adds precision to the more commonly recognized indicators. On the types of range studied, relative amounts of common perennial grasses, better than any other indicator, show the early changes toward range recovery or toward range deterioration. 3. When the productivity of the range has not been greatly impaired by prolonged overuse and erosion, the rate of range recovery under conservative grazing is approximately equal to the recovery rate obtained under total protection from grazing by domestic livestock. 4. Tall, coarse-stemmed grasses such as Arizona cottongrass, sideoats grama, and black grama attain a high percentage of the total perennial grass cover under long periods of protection--a condition which appears to confirm the belief that these grasses are important members of the semidesert grassland climax vegetation. 5. Populations of relatively unpalatable deep rooted shrubs and tre

Perennial Grass Composition as an Indicator of Condition of Southwestern Mixed Grass Ranges

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