THE MAJOR RANGE TYPES

E. J. Woolfolk, D. F. Costello, B. W. Allred

MORE THAN half the area of continental United States produces native vegetation suitable for grazing by livestock. Three-fourths of this range area lies west of a line that roughly bisects the Great Plains from Canada to the Gulf of Mexico. About a fifth is graze-able forest and other lands in the South and Southeast, and the remainder lies chiefly in the Missouri Ozarks and the Ohio and Mississippi River basins.

These millions of acres can be classified into several broad range types which differ significantly in vegetative character and composition, climate, topography, and soil. Research and the experience of stockmen have defined kinds of operations and systems of management generally suitable for sustained production in each major type. Before we had that knowledge of true range values, widespread misuse brought serious deterioration, some of which has not been mended to this day.

Now that we have the knowledge, the future of the range livestock industry hinges on its application on the restoration and sustained sound management of these major range areas.

The first is the tall-grass type. Under almost ideal conditions for the evolution of grassland, the tall-grass prairie developed throughout the Midwest and eastern Great Plains. The white man quickly converted the most fertile sites into farms, which today constitute a valuable agricultural section. About 20 million acres, mostly in private ownership, remain of the original tall-grass prairie, but they have been greatly modified by the introduction of exotic grasses and in places by deterioration.

The mixture of tall grasses and showy herbs, with an understory of short grasses and sedges, produces abundantly with average annual rainfall ranging from 20 inches in North Dakota to 40 or more inches in parts of Oklahoma and Kansas. The grazing capacity is high; only 3/4 to 1 1/2 acres are needed to supply an animal-unit-month of forage. The prairie vegetation does not cure well when left standing, however, and is therefore of little value for late-fall and winter grazing.

The highly prized bluestem area in the Flint Hills and Osage sections of Kansas and Oklahoma are usually stocked lightly in summer to permit maximum gains on cattle marketed grass-fat in August. In the sand hills of Nebraska yearlong grazing of breeding cattle with considerable feeding of native hay in winter is the usual range practice.

As a result of severe drought and too heavy grazing, particularly during the middle 1930's, low-value weeds and shrubs in many places replaced the valuable bluestems, Indiangrass, switchgrass, and some other characteristic species. Although some recovery has since occurred with lighter stocking and favorable weather, present livestock inventories indicate that the remaining tall-grass ranges may again be too heavily stocked.

The tall-grass prairie has high recuperative power, and forage production may increase considerably through application of good range management and soil conservation practices. The native grasses have deep, fibrous roots and produce an abundance of natural mulch, which carries over winter; hence rainfall readily sinks in and excessive runoff is prevented.

Short Grass

The short-grass range, the largest and most important grassland type in the United States, extends from the Texas Panhandle northward beyond the Canadian border and from the foothills of the Rocky Mountains eastward midway into the Dakotas. An arm also extends westward from Texas across central New Mexico to northeastern Arizona. This area, now mostly in private ownership, has such valuable livestock forages as the grama grasses, buffalograss, bluestem or the western wheatgrass, and needle-and-thread.

Forage production coincides with the occurrence of spring and early summer precipitation, which totals about three-fourths of the 13-inch annual average in the Northern Plains and somewhat less of the higher annual average in the Southern Plains. Curing occurs toward the end of the hot, dry summer and the forage retains much of its nutritive quality throughout the winter. Grazing capacity is about 2 1/2 to 4 acres per animal-unit-month in the Northern Great Plains and from 5 to 10 acres in the Southwest.

Range-cattle grazing in spring, summer, and fall is important throughout the type, and the nutritious native forage also provides adequate yearlong grazing in favorable winters.

Cow-and-calf operations predominate, but many grass-fat and feeder steers go directly to midwestern markets or into feed lots for finishing.

Sheep grazing is also important in the Northern Great Plains. Because most of the forage is provided by grasses which are normally dry during much of each year, only relatively few slaughter lambs are produced. Instead, the lambs are marketed largely as feeders. Yearling ewes produced on short-grass ranges are in good demand for breeding herds in other areas.

Yearlong maintenance of many antelope, deer, and game birds is another important function of the short-grass type.

Before and during the First World War, and in the early 1920's, widespread deterioration of short-grass ranges resulted from futile attempts to raise wheat on part of these semiarid lands, submarginal for crop production. This took millions of acres almost entirely out of range forage production for many years and reduced their grazing value to a fraction of what it once was.

Drought, a common phenomenon in the Great Plains, especially in the Southwest, reduces the stand and production of forage, causes heavy losses of livestock, and in the central and southern parts accelerates wind erosion. Severe drought and heavy grazing during the middle 1930's depleted the "upside down" ranges and severely reduced the unplowed cover. Additional acreages were devastated by the deposition of wind-blown soil. The forage species are phenomenally resistant to both drought and grazing, but, once depleted, require several years of good management and favorable weather for complete recovery. Nearly a decade of favorable weather and somewhat lighter stocking since the drought over most of the short-grass country have enabled some sections, particularly the Northern Plains to recover to (or slightly above) pre-drought levels in vegetative cover and forage production.

Semidesert Grass

Good seasonal forage production, high nutritive values in cured forage, and mild winters place the semidesert grasslands of central and southwestern Texas, Arizona, and New Mexico among the best yearlong ranges in the country. The characteristic rich mixture of grasses, annual and perennial weeds, or forbs, and scattered shrubs and trees provide an average grazing capacity of 6 to 7 acres per animal-unit-month.

Variable topography and a wide range in elevation make for differences in climate and soil and in kind and amount of vegetation. Growing conditions are severe. Drought is frequent.

The grama grasses and curly-mesquite reach their maximum production at the higher elevations in the western part where annual rainfall averages 15 to 18 inches. These species cure well on the ground and are therefore suitable for summer, winter, or yearlong grazing.

At the lower elevations, where precipitation may be as low as 8 inches annually, black grama, the three-awns, and dropseeds usually predominate,with a heavy sprinkling of shrubs. In local low sites, which are alternately very wet and dry, tobosa grass and alkali sacaton often dominate the vegetation. Use in summer of tobosa grass, three-awns, and dropseeds renders more of the grama forage available for the remainder of the year. Extreme depletion of the tobosa areas through heavy grazing converts them into barren adobe flats.

Scattered throughout this rich grassland type are many shrubs, dwarf trees, yuccas, and cacti. Some of these, such as saltbush, mesquite, ratany, and scrub oak, are rather palatable and provide some forage, especially in winter and spring, and for goats yearlong.

Although especially adapted to grazing by breeding cattle, the semi-desert grassland type in Arizona provides good winter sheep range. In the Edwards Plateau section of southwestern Texas both sheep and goats are grazed yearlong. There the production of feeder lambs is generally secondary to wool and mohair. Many lambs wintered in this area go grass-fat to a spring market. Cattle, sheep, and goats are frequently grazed in common. Lighter stocking generally will aid sustained production.

Pacific Bunchgrass

Although greatly changed since settlement, the Pacific bunchgrass prairie is still a valuable grassland. Much of the area it once occupied from western Montana through the Pacific Northwest to southern California has been converted to wheat or other agricultural production. The remaining part forms a rather narrow belt along the foothills throughout the range.

Bluebunch wheatgrass, Idaho fescue, pine bluegrass, and California needlegrass, although well adapted to the long, dry summers and moist winters characteristic of the type, withstood grazing poorly and have largely been replaced by annuals. These annuals alfileria, bur-clover, slender oatgrass, cheatgrass, and others provide good forage when green. Growth starts in the fall and the plants, both annuals and perennials, remain green through the winter. Abundant growth starts rapidly in early spring. Because the annual type of forage dries up and declines in palatability and nutritive value after spring growth is completed, the type has rather low value for summer grazing.

Spring-fall grazing by cattle and sheep is most common in the North, but under favorable conditions and in the South or where perennials remain, yearlong use is feasible. On the average, 4 to 6 acres is now required to support an animal unit for 1 month. Improved management could doubtless double the productivity.

Sagebrush Grass

The sagebrush grass type occurs from northern New Mexico and Arizona northwestward into Montana and to the east slope of the Cascades in the Pacific Northwest.

It is typical of rather dry valleys and basins where most of the meager annual precipitation occurs during the winter and spring seasons. It is the third largest of all range types and twice as large as any other major shrub type. Its main value lies in the palatable herbaceous perennials that grow under and between the sagebrush plants. Bluebunch and bluestem wheat-grasses, and needle-and-thread, Indian ricegrass, Sandberg bluegrass, and palatable weeds provide most of an average grazing capacity of 9 to 15 acres per animal-unit-month, only one-third of what it should be.

Throughout its northern extension, this type forms an indispensable link, both spring and fall, between summer and winter ranges for cattle and sheep. To the south, at the higher elevations, winter grazing by sheep is somewhat more important.

The sagebrush itself provides little forage except in winter when heavy snows occasionally cover the grasses. For the sustained production of forage and livestock, sagebrush grass ranges should be stocked conservatively on the basis of the herbaceous-perennial understory.