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Vegetation Response on Allotments Grazed under Rest-Rotation Management

1986; University of Arizona; Volume: 39; Issue: 2 Linguagem: Inglês

10.2307/3899292

2162-2728

Richard E. Eckert, John S. Spencer,

Aeolian processes and effects

The effects of grazing management systems on plant communities in the GreatBasin are largely unknown.This study is a quantitative description of the response of vegetation from 1973 to 1983 on the Goldbanks and Pueblo Mountain cattle allotments in northern Nevada managed under a 3-pasture rest-rotation grazing system.Shrub canopy cover, basal-area cover of herbaceous species, and frequency of occurrence of all species were used to estimate change in vegetation characteristics on macroplots representing 9 community types.Forage use was heavy in all years and averaged 65% in June, 75% in July and August, and 80% in October.Sandberg bluegrass [Poe sandbergii Vasey] and sagebrush [Artemisia spp.L.] were the most responsive species.Long-term increases or decreases in frequency and cover of desirable grasses were found on very few sites.Perennial forbs increased on a number of sites.Short-term changes in frequency and cover of Sandberg bluegrass and in frequency of sagebrush seedlings and young plants were attributed to a sequence of dry and wet years and to level of competition from herbaceous species.Frequency data indicated more significant changes in species composition than did cover data.The management system, forage utiliwtion levels imposed, and climatic conditions present maintained prestudy range condition throughout the study on most sites at Pueblo Mountain.An increase in frequency and cover of Wyoming big sagebrush [A.tridmtata wyomingensis Beetle] and a decrease in the cover of desirable grasses at Goldbanks suggest a downward trend in range condition on some sites where either Thurber needlegrass [Stzpo thurberhma Piper] or bluebunch wheatgrass [Agmpyron spicatum (Pursh) Scribn.& Smith] is the potential dominant grass.Many hectares of western rangeland presently are managed under intensive grazing systems.By 1978 for example, allotment management plans had been implemented on about I I million ha managed by the Bureau of Land Management (BLM) (USDI 1978).About 2 million ha were under intensive management in Nevada.In addition, the "Proposed Action" in many current Environmental Impact Statements and Resource Management Plans indicates that grazing systems will be the primary means of range improvement in the future.In many cases, intensive management has come to mean deferred or rest-rotation grazing systems.Hickey (1967) and Herbel(l971) described many kinds of grazing systems and results obtained.Hormay (1956, 1970) Hormay and Evanko (1958) and Hormay and Talbot (1961) discussed the reasons for range deterioration and developed a 5-pasture restrotation grazing system for improving bunchgrass range in northeastern California.Hughes (1979Hughes ( , 1980) ) reported the effects of rest-rotation management on the Arizona Strip of southern Utah and northern Arizona.Laycock and Conrad (1981) evaluated the response of vegetation and cattle to several grazing systems on mountain rangelands of eastern Utah.Johnson (1965) and Gibbens