Agronomy and Horticulture Department


Date of this Version



Published in ECOLOGY, Vol. 20, No.3, July, 1939


The severe drought of 1934 to 1938 has resulted in great losses in the plant
populations of native pastures. In Nebraska, little bluestem, Andropogon scoparius, and Kentucky bluegrass, Poa pratensis, have almost disappeared, while big bluestem, Andropogon furcatus, and numerous other important pasture grasses have suffered heavy losses. In addition to shiftings within the plant populations to compensate these losses, such as an enormous increase in side-oats grama, Bouteloua curtipendula, notable and widely spread local extensions have occurred. Over thousands of pastures western wheat grass, Agropyron smithii, has spread widely, and in similar numbers sand dropseed, Sporobolus cryptandrus, has become a dominant or the dominant species in these grazed areas.

Degeneration of prairies under the impact of grazing and subsequent changes in the vegetation under continuous pasturing have been consistently studied over a period of ten years. Examination of extensive field notes taken before the dry period began in 1932 reveals the fact that formerly the sand dropseed occurred only rarely or very sparingly. Following the destructive drought of 1934, it rapidly increased in abundance and in two or three years became one of the most important pasture grasses. Many inquiries have been received from farmers and stockmen regarding this" new pasture grass."