ABSTRACT:
Native prairie communities have evolved to produce relatively low but sustained production. Demand for greater production has resulted in overgrazing and, consequently, lower and more unstable annual yields and increased risk of soil erosion. Because the Rough Fescue Prairie is best suited for grazing, studies were made to determine its carrying capacity and assess the effects of overgrazing. Overgrazing resulted in an increase in plant species that were shallow-rooted and less productive, but more resistant to grazing. This was associated with higher soil temperatures and reduced infiltration. Consequently, the soil was transformed to one characteristic of a drier microclimate. Soil color changed from black to dark brown as stocking rate increased from light to very heavy. Grazing caused a redistribution of nitrogen in the soil by concentrating a greater proportion in a shallower Ah horizon. Productivity deteriorated rapidly with overgrazing, but more than 20 years of drastically reduced stocking rates are required to enable recovery.
Footnotes
Johan F. Dormaar is a soil scientist and Walter D. Willms is a range ecologist at the Agriculture Canada Research Station, Lethbridge, Alberta TIJ 4BI. This article is LRS contribution no. 3878947.
- Copyright 1990 by the Soil and Water Conservation Society
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