Agronomy and Horticulture Department


Date of this Version



Published in Ecology, Vol. 29, No. 1 (Jan., 1948), pp. 1-29. Copyright Ecological Society of America. Used by permission.


When the early settlers came to Iowa, Nebraska, and adjacent territory they entered an almost boundless sea of grass. Throughout the years the prairie has been largely broken for crop production, but even today there still remain considerable tracts of native grassland annually mowed for hay and far greater ones of native pasture (Weaver and Fitzpatrick, '34). Climax grassland when grazed lightly or moderately may retain essentially its natural composition over extremely long periods. It is only when grazing animals are circumscribed in their range by fences and when too large a population is thus confined for too long a time that grazing and trampling become so excessive that the normal cover cannot be maintained. The prairie degenerates. The best-liked and most nutritious grasses and forbs wane and disappear. They are replaced by species of lower grazing value. Weeds become abundant. The farmer or rancher says the prairie has been "grazed out." Often the land is plowed and thus another tract of prairie forever disappears. Although extensive researches have been made upon degeneration of upland prairie under excessive pasturing, it is believed that similar studies of the break-down of postclimax prairie on lowland have not been recorded (Weaver and Hansen, '41, '41a). The area of this research lies in the west-central portion of the great body of grassland, now largely broken, known as true or mid-grass prairie.