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Sage-grouse (Centrocercus urophasianus and C. minimus) historically inhabited much of the sagebrush-dominated habitat of North America. Today, sage-grouse populations are declining throughout most of their range. Population dynamics of sagegrouse are marked by strong cyclic behavior. Adult survival is high, but is offset by low juvenile survival, resulting in low productivity. Habitat for sage-grouse varies strongly by life-history Current Ran e

Prior studies of pinyon-juniper woodlands at a few locations have indicated considerable historical expansion of the trees and loss of understory. Whether these changes are a widespread phenomenon and related to pervasive, rather than local, influences was the question asked by this research. An objective sampling of 18 randomly selected mountain ranges in the Great Basin was undertaken. Tree age and dominance in the pinyon-juniper woodlands showed definite geographical, elevational, and historical trends. The oldest, most tree-dominated woodlands were located in areas of intermediate topography where disturbances may have been less frequent. Populations of both tree species [Pinus monophylla (Torr.) and Juniperus osteosperma (Torr. and Frem.)] were progressively younger and less dominant in both upslope and downslope directions from the intermediate elevations. Tree densities have also historically increased within the oldest woodlands. Pinyon density has increased faster than that of juniper. Approximately 40 percent of the sampled plots had their trees establishing during the last 150 years. These changes generally coincide with introduction of heavy livestock grazing, tree utilization by the mining industry, and fire suppression that followed settlement of the region. Associated climatic trends were also investigated. The relative importance of these influences on the changes in tree age and dominance cannot be determined without further research. The loss of understory, coincident with increasing tree dominance, has reduced forage production and made the woodlands progressively less susceptible to fire. Barring some major environmental change or management action, this forage reduction and decreased frequency of burning will continue until trees dominate much more area.

Invited Synthesis Paper NEIL E. WEST has offered his overview of how the issues of biodiversity may influence planning, research, and management of rangelands. Neil grew up on a cattle and sheep ranch in southern Oregon. He went to Oregon State University with the intention of becoming a chemist. His career was irrevocably changed, however, when he learned, in an introductory zoology class, about the outdoor orientation of the then esoteric science of ecology. He attained a B.S. in general science and continued directly into a Ph.D. program in plant ecology at OSU. His doctoral work focused on the effects of fire exclusion on ponderosa pine forests in central Oregon. After a short assignment at the Oregon Forest Research Lab in Corvallis, West decided to relocate to the drier terrain of Utah. West has been at Utah State University, Logan, most of the time since 1964. L.A. Stoddart and C.W. Cook were important early mentors. He has tried to overcome his western biases by spending a semester or more at the

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Sage-grouse (Centrocercus urophasianus and C. minimus) historically inhabited much of the sagebrush-dominated habitat of North America. Today, sage-grouse populations are declining throughout most of their range. Population dynamics of sagegrouse are marked by strong cyclic behavior. Adult survival is high, but is offset by low juvenile survival, resulting in low productivity. Habitat for sage-grouse varies strongly by life-history Current Ran e

Most studies of the impacts of fire in sagebrush-grass vegetation in the Great basin have involved recovery on sites seriously depleted of native perennial bunchgrasses. The usual recommendation is to promptly seed such areas artificially. This is costly, not alwayssuccessful, and if unnecessary, could produce no more than a natural recovery. The natural recovery of a good condition sagebrush-grass site in central Utah was monitored for 2 years after a midsummer wildfire. Total plant cover 1 year after the fire was similar to that before the fire and on unburned controls. Annual herbaceous growth 1 year later was almost twice that before the fire. Most of the plant growth the first year was due to cheatgrass (Bromus tectorum). By the second year after fire, however, the perennial bunchgrasses had cover and production levels near those recorded prior to the burn. Two years after the Bre, total grazable forage was 2.5 times that before the fire. Total precipitation, however, had been higher than average both years. Sagebrush-grass sites in good condition may be improved for cattle production with a few years of livestock exclusion following wildfire. Prescribed or controlled burns would probably be appropriate on similar high condition rangelands if cattle grazing is the dominant use and conflicts with wildfire are minor.