America's Northern Plains
An Overview and Assessment of Natural Resources
Grazing Lands
Rangeland in the Northern Plains region comprises 43% of the landscape and is nearly one-third of all rangeland in the conterminous U.S. Of the total acreage of rangeland in the region (180 million acres), 26% is associated with soils of high wind erosion potential, and over 40% occurs in association with fragile soils (T < 3 tons/acre/year; T=Tolerance).
This rangeland helps support about 23 million head of cattle in the region, or 24% of the U.S. cattle population (Figure 11), and 3 million head of sheep, about 32% of the U.S. sheep population (National Agricultural Statistics Service, 1995). Many wildlife species also depend on rangeland habitat.
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Figure 11. Breakdown of cattle numbers in the Northern Plains (NASS, 1995). |
Of the 180 million acres of rangeland in the Northern Plains, 157 million acres are privately owned. The private rangeland includes 4 million acres of wetland identified by using the Cowardin Classification System (NRI, 1995).
Pastureland in the Northern Plains comprises 3% of the landscape, with 13 million acres privately owned. Soil loss on pastureland generally is very low, and at present no standard methods exist for evaluating its condition, quality, or health (Figure 12).
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Figure 12. Tons per acre of soil loss by land use in the Northern Plains (USDA/NRCS, 1994). |
Range condition data show that 71 million acres of rangeland in the Northern Plains are in poor and fair condition. This indicates a loss of higher successional plants in the plant community, which can result in loss of wildlife habitat, increased water runoff with increased soil erosion, increased soil loss from wind erosion, loss of species diversity, and decreased productivity.
Rangeland apparent quality or condition data for 1982 and 1992 show a 9% increase of rangeland with a worsening (negative) condition and only a 2% increase of rangeland with an improving (positive) condition (Figures 13 and 14). Thus, some rangeland plant communities are slowly losing quality or moving toward nonsustainability.
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Figure 13. Range condition classes by acres in the Northern Plains (USDA/NRCS, 1994). |
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Figure 14. Acres of apparent trend on rangeland in the Northern Plains (USDA/NRCS, 1994). |
The 1992 NRI data show that 98 million acres (62.5%) of rangeland in the Northern Plains need conservation treatment in three major categories. Grazing management (controlling/managing the grazing animals) to improve the plant community is needed on 53% of the rangeland; erosion control is needed on 26%, mostly for wind erosion occurring in Wyoming and Colorado (Figure 15); and weed or brush control is needed on 8%.
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Figure 15. Rangeland soils with high potential for wind erosion in the northern Plains region. By W.J. Waltman and B. Stephens, USDA, NRCS. Source: R. Srinivasan (1995); Blackland Research Center, Texas Agric. Expt. Station, Temple, TX 76502, Albers Equal Area Projection, Dec. 1995, Map Series No. 95-0027, Northern Plains GIS/Remote Sensing. Rangeland soils with high potential for wind erosion were derived from wind erodibility group 1 to 3 in the State Soil Geographic Database (STATSGO; Soil Survey Staff, 1994). Rangelands were derived from the USG 1:250000 Land Use and Land Cover Digital Data (USGS, 1986). |
A significant noxious weed problem also appears to exist in some of the northernmost Northern Plains states. The main two noxious weeds are leafy spurge and spotted knapweed, but data are not readily available for monitoring the spatial extent of the problem.
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