Treesearch

Among factors selecting for rapid growth rates in avian young are those that cause mortality of whole broods (e.g., predation, weather) (Ricklefs, Ecology 50:1031-1039, 1969). Abert's Towhee (Pipilo aberti) endures a high rate of nesting mortality caused by predation and brood parasitism (Finch, Condor 83:389, 1981; Condor 85:355-359, 1983). Predation is the principle factor causing loss of whole broods. Nesting mortality may have an important role in the development of life history traits (e.g., nestling growth, clutch-size, number of broods/season) in Abert's Towhee, yet little is known...

This guide for range managers and users is a distillation of the most important research findings over the past 50 years. The research provides a strong scientific basis for planning and decisionmaking in the management of the saltdesert shrub rangelands of the Great Basin and lntermountain areas, which cover some 40 million acres. Much of the research took place in the USDA Forest Service's Desert Experimental Range in southwestern Utah.

Volume and biomass equations were developed for curlleaf cercocarpus (Cercocarpus ledifolius Nutt.) in the Egan and Schell Mountains near Ely, NV. The equations predict cubic foot volume of wood and bark for variable minimum branch diameters. Wood density factors are given to convert volume predictions to pounds of fiber biomass. The reliability of the equations was assessed using the jackknife technique to construct confidence intervals.

Statistical models are presented which relate near-view scenic beauty of ponderosa pine stands in the Southwest to variables describing physical characteristics. The models suggest that herbage and large ponderosa pine contribute to scenic beauty, while numbers of small and intermediate-sized pine trees and downed wood, especially as slash, detract from scenic beauty. Areas of lower overstory density and less tree clumping were preferred. Moderate harvest of relatively dense stands tends to improve scenic beauty once the stand has recovered from obvious harvest effects. The recovery period...

Plant communities are inherently variable due to a number of environmental and biological forces. Canopy cover and aboveground biomass were determined for understory vegetation in plant communities of a prairie grassland-forest ecotone in southeastern Montana. Vegetation units were described using polar ordination and stepwise discriminant analysis. Nine of a total of 88 plant species encountered and cover of litter were the most useful variables in distinguishing among vegetation units on the study area and accounted for nearly 100 percent of the variation in the data. Seven vegetation...

Black-tailed prairie dog (Cynomys ludovicianus) control by poisoning with zinc phosphide was not economically feasible in the Conata Basin of South Dakota. Economic analyses were conducted from U.S. Forest Service and rancher viewpoints. Control programs were analyzed with annual maintenance or complete retreatment of initially treated areas to prevent prairie dog repopulation and, except for annual maintenance at low repopulation rates, were unable to recover initial control costs. At a prairie dog repopulation rate of 30% per year (the most realistic projection), prairie dog control was...

Analyses of 43 blue spruce populations at age 12 (9 years in the field) revealed significant differences among populations for survival, height, vigor, crown diameter, frost injury, and foliage color. Use of regions increases the probability of locating better seeds sources, but high variability among individual populations within regions limits their value in specifying where better seed sources can be collected. Phenotypes should be selected in best stands within regions.Dataset for this publication

The loss of suitable, high quality habitat is a major problem facing big game managers in the western United States. Agricultural, water, road and highway, housing, and recreational development have contributed to loss of natural big game habitat (Wallmo et al. 1976, Reed 1981). In the western United States, surface mining of minerals has great potential to adversely affect localized big game populations (Reed 1981). Helms (1978) discussed negative and positive impacts of mine development on pronghorn (Antilocapra americana) in Wyoming. He reported an actual increase in pronghorn population...

Linear regression equations were developed to predict stand volumes for aspen given average stand basal area and average stand height. Tables constructed from these equations allow easy field estimation of gross merchantable cubic and board foot Scribner Rules per acre, and cubic meters per hectare using simple prism cruise data.

Coyotes (Canis latrans) are one of the most widely studied animals in North America. The primary reason that much effort has been directed toward understanding the coyote is its feeding patterns. Coyotes prey upon domestic animals (Murie 1951, Gipson 1974, MacCracken 1982) and game animals (Fichter et al. 1955, Beasom 1974, Salwasser 1974, MacCracken and Hansen 1982), and feed on fruit and vegetable crops (MacCracken 1982). Presumably, the primary objective of most coyote research is to gain knowledge of coyote ecology which can be used to decrease conflicts with man.