Treesearch

The aspen ecosystem is rich in number and species of animals, especially in comparison to associated coniferous forest types. This natural species diversity and richness has been both increased and influenced by the introduction of domestic livestock. The high value of the aspen type as a forage resource for livestock and as forage and cover for wildlife makes the subject of animal impacts important to understanding and management of this ecosystem.

Although many diseases attack aspen, relatively few kill or seriously injure living trees. The common leaf diseases, in general, are widely distributed throughout the range of aspen, whereas there are subtle differences in distribution between the important decay fungi, and apparently entirely different areas of distribution of major cankercausing organisms. However, there still are large gaps in knowledge of the disease organisms and their influence on natural and regenerated stands.

Aspen has been recognized for many years as being very intolerant of shade (Baker 1918a, Clements 1910, Weigle and Frothingham 1911, Zon and Graves 1911). In dense stands, vigorous aspen trees are confined to the dominant and codominant crown classes. Regardless of size, when they are overtopped by larger trees, aspen trees deteriorate and eventually die. Many well-stocked, even-aged aspen stands have virtually no aspen regeneration beneath them, even in the form of small ephemeral suckers (Beetle 1974, Jones 1974b). In contrast, healthy coniferous seedlings may be plentiful under the...

Factors considered most critical in selecting a specific wilderness environment in which to recreate are likely to vary depending upon the type of environment involved, the range and extent of experience of the recreationists, and the situational context of the decision (whether a real or a hypothetical decision was made). This study examines differences in factors considered in choosing a wilderness environment based upon whether the choice was an actual report of behavior or a hypothetical decision. A questionnaire requesting information concerning choices of wilderness areas in which to...

Burrowing Owls (Athene cunicularia) in southwestern South Dakota frequently use the burrows of black-tailed prairie dogs (Cynomys ludovicianus) for nesting and escape cover. Coulombe (1971) emphasized the importance of understanding the role of burrow selection in relation to owl behavior, physiology, and overall ecology. He also suggested that availability of burrow sites may be the critical factor in Burrowing Owl population dynamics.

Plant communities of southeastern Montana were surveyed for rodents over a two year period. Deer mice (Peromyscus maniculatus) were the most abundant rodent species found on the study area. Prairie voles (Microtus ochrogaster), meadow voles (M. pennsylvanicus), sagebrush voles (Lagurus curtatus), Wyoming pocket mice (Perognathus fasciatus), thirteen-lined ground squirrels (Spermophilus tridecemlineatus), least chipmunks (Eutamias minimus), and eastern fox squirrels (Sciurus niger) also were captured. Grassland, riparian, and sagebrush communities showed the greatest rodent abundance and...

In some areas, many aspen stands are all the same age, dating from a single great fire or a year of widespread fires (fig. 1). The 1879 fire in the Jackson Hole region of Wyoming (Loope and Gruell 1973) and the 1904 fires in Arizona's White Mountains (Kallander 1969) are examples. Choate (1966) found that almost all aspen stands in New Mexico were even-aged, many of them originating after fires dating since the mid-1800s. Some authors (Fetherolf 1917, Langenheim 1962, Marr 1961, Reed 1971), considered aspen to be climax in some habitats. Others, notably Baker (19251, felt that all aspen...

Burrowing Owls (Athene cunicularia) were studied in a prairie dog town of southwestern South Dakota. Pellets regurgitated by Burrowing Owls contained a wide variety of prey remains. Insects, spiders, small mammals, and vegetation were the most frequent items identified in the pellets. Mammals were consumed most frequently during spring and early summer. Insects were consumed in large numbers during the entire period of this study, but they became more frequent in owl pellets during late summer and fall in association with a decline of mammal remains. Some prey items observed around owl...

Presents an overview paper and 11 contributed papers focused on the issue of the processes that underlie decision making by recreationists. The papers span a range of topics including the theory of choice behavior, empirical investigations of choice, and methodological approaches to the study of choice behavior.

The relevancy of a lexicographic semi-order model, as a basis for development of a microcomputer-based decision aid for backcountry hikers, was investigated. In an interactive microcomputer exercise, it was found that a decision aid based upon this model may assist recreationists in reduction of an alternative set to a cognitively manageable number.