WHY GRASSES ARE SUPERIOR AS FORAGE PLANTS Grasses generally constitute forage of the first quality on range and pasture. The particular habit of growth of grass herbage, its high nutritive value for all classes of foraging animals, its comparative permanence and slight variation in yield from year to year, make it more desirable for pasture purposes than any other great class of plants. The active growing region of the grass blade is at the base; hence the production of herbage is not checked by grazing, provided the plant is physiologically strong. The growth of the leafage of such plants as geranium, mertensia, and snowberry, on the other hand, is uniform throughout the entire leaf, and therefore the total consumption of their leafage by grazing practically arrests further development of the leaves eaten. Perennial grasses as a whole are found to hold the climax place successionally in herbaceous vegetation, so that the grass type is much more stable than is that of other herbs. Therefore, if appreciable and permanent improvement in the grazing capacity of the range is to be obtained, it must come in large measure through the grasses. Tests with tall larkspur and certain other poisonous species have brought out the fact that they can be killed out on the range if cut closely when about 6 inches high, twice in the first season of treatment and once in each of the two following years. Some of the palatable herbaceous species are quite as readily destroyed by close cropping. Perennial grasses, however, ordinarily hold up well under the treatment which eradicates larkspur. RANGE RESEEDING Occasionally a long-used grazing area supports little vegetation of value to livestock. On the steeper, poorly vegetated hillsides erosion may be leaching out and transporting to lower levels the soluble salts and organic acids essential to the establishment of an effective plant cover. Moreover, because of the small quantity of humus on the range, the soil packs heavily, especially if animals are admitted during wet weather, which decreases still more the waterholding capacity of the soil and the ability of the range to revegetate. A large proportion of the depleted mountain meadows and welldrained parks at high elevations, where the plant cover has declined in recent years, have fertile soils capable of supporting a good stand of vegetation and usually have sufficient soil moisture. The possibility of successful reseeding to valuable cultivated and native species is considerably greater for such areas than for the drier lands lying at lower elevations (Pl. IV). Attempts to reseed artificially the plains and the drier foothills to cultivated forage plants have given results of no practical value. In view of the none too promising results obtained from the artificial reseeding of range lands, coupled with the high cost, any far-sighted stockman will take the necessary precautions to keep his range in good, vigorous productive condition, and certainly will not allow it to deteriorate beyond a stage where it can readily be brought back by natural revegetation. NATURAL REVEGETATION Cropping a pasture each year to the maximum of its forage production is sure, sooner or later, to cause a sharp decline in its grazing capacity. The most successful stockmen are now grazing their ranges on the basis of the quantity of forage produced in the average year rather than on the maximum yield in the best years. This plan, in view of the yearly fluctuation in forage production, nearly everywhere in the West, is insurance second to none against financial loss. Improvement in the grazing capacity of native pasture lands, the forage of which is composed largely of bunch grasses, is dependent, periodically at least, upon a good production of fertile seed. To insure seed production of the more palatable forage plants requires avoidance of overgrazing, prevention of too early grazing, and effective control and distribution of livestock. OPERATION OF DEFERRED AND ROTATION GRAZING The "deferred and rotation grazing plan has been adopted widely on national forest ranges in order to obtain the greatest possible use of the forage and at the same time keep the lands in a high state of productivity. The plan is based upon the growth requirements of range vegetation, coupled with methods of handling livestock to foster seed production, provide for the planting of the seed crop, and furnish forage for the stock during the revegetational period. Briefly, the plan is to reserve some portion of the range for cropping after the seed has ripened. The following year, in order to avoid the destruction of the seedlings which originated from the seed of the first year's crop, and to provide for additional seed where needed, the same area is usually reserved a second time. If after two years of such deferred grazing the forage plants have become vigorous and an ample number of seedling plants have become established, a second area in need of seeding is selected and the tract upon which grazing was originally deferred is cropped before seed maturity. This plan of deferring the grazing on one depleted area and then on another is continued until the entire range has been revegetated. After that, grazing after seed maturity is alternated or rotated from one portion of the range to another in order to allow an occasional seed crop of the better forage plants to develop and replace the decadent vegetation. This continuous rotation in the grazing plan has the big advantage over yearlong rest or of a heavy reduction in the stock during the period required for revegetation that it interferes not at all with the production of beef or mutton. (3, 5, 6.) Deferred grazing has been attempted without adjustment in the number of stock on overstocked ranges where improvement in the plant cover was badly needed. Because of the overstocking it was necessary to crop the forage on the unreserved parts three or more times before seed maturity. These attempts have shown clearly that the deferred grazing plan can be applied successfully only if the number of livestock corresponds with the actual grazing capacity of the range; otherwise the parts grazed before seed maturity will be so seriously overgrazed as to offset the benefit to the reserved area. Deferred grazing has been applied on national-forest range in the West so widely and for so many years that the good results to both stock and range are indisputable. Improvement is invariably rapid where there remains a fair stand of seed plants. Naturally, considerable time is required to increase appreciably the forage cover on lands which for many years have been in a low state of productivity, and especially on those which support few highly palatable seed plants. Without the adoption of some grazing plan, however, such as deferring the cropping until the seed of the more desirable palatable vegetation has matured, or decreasing materially the number of livestock formerly grazed, or actually removing the animals for a year or more, there is little chance of increasing the range returns from badly depleted lands, of controlling erosion, or of improving the efficiency of important watersheds in one way or another. Any kind of plant cover is preferable to denudation or to the production of a growth so sparse that the fertility of the soil tends to decline rather than improve. SOIL FERTILITY AND FORAGE TYPE It is well known that different species or types or vegetation vary considerably in the quantity of water they require and in the type of soil necessary for their development (7). The earlier stages of plant cover, such as are found on semidecomposed soil, poor in organic matter and comparatively low in available moisture, consist of shallow-rooted early-maturing annual species. Although widely spaced at first, these plants gradually increase in density until practically all of the available soil moisture is used up by the vegetation. When this annual plant growth reaches maturity and dries up, a large proportion of the soil surface is exposed. (Pİ. V, fig. 1.) Small protection is thus given the soil by annual vegetation as compared with that given by perennials. Not only does the range which supports annuals ordinarily furnish only a small quantity of rather inferior forage, and practically none unless cropped when the leafage is succulent, but it must be grazed lightly and with more than usual care. Where deferred grazing is applied for several years in succession, however, even lands on which annuals predominate show improvement in the plant cover. Eventually the vegetation changes to a more permanent or stable type, and the quantity of palatable herbage is correspondingly increased (8, pp. 1–7). RESEEDING TESTS ON PROTECTED AND DEFERRED GRAZED PLOTS In order to determine the time required to revegetate lands in different degrees of depletion, both protected and unprotected experimental plots varying in size from a few square feet to several acres were established in each of the major zones and forage types and on different slopes and exposures. The density and composition of the vegetation on these plots were carefully recorded, the quadrat plan of mapping being used with adaptations. On the larger plots the plant associations which made up the cover were merely outlined and the species and the density of each recorded. |