Treesearch

A deterministic model of succession in aspen forests was developed using existing data and intuition. The degree of uncertainty, which was determined by allowing the parameter values to vary at random within limits, was larger than desired. This report presents results of an analysis of model sensitivity to changes in parameter values. These results have indicated areas of needed research. The model responds realistically to various management techniques and could be an aid to resource managers in their decisionmaking process.

The proceedings summarizes recent research and existing literature pertaining to the restoration and management of game and livestock ranges in the Intermountain Region. Improved plant materials and planting practices are emphasized. The series of 28 papers was presented at the Restoration of Range and Wildlife Habitat Training Sessions held in Twin Falls, Idaho, September 15-17, 1981 and in Elko, Nevada, June 22-24, 1982.

One of the most common types of data used in applied wildlife management is the population ratio. These data are used to gauge reproductive success and the effect of selective harvesting of wildlife.

These proceedings include 41 papers focusing attention on the need to integrate management of snags - dead or deteriorating trees critical to needs of cavity-dependent wildlife - with other resource uses and demands. Sessions concentrated on management, habitat and species requirements, and monitoring and modeling.

The condition of campsites was examined in the Bob Marshall Wilderness, Montana. The amount of change that has occurred on these sites was inferred by comparing campsites with comparable control sites. Trampling disturbance - loss of vegetation, exposure of mineral soil, and compaction of the soil - was generally comparable to that found in other backcountry areas. Campsites were unusually large, however, and tree damage was severe. Such impacts were particularly pronounced on sites used by outfitters and large parties with stock. Actions for reducing damage are suggested.

Rehfeldt, Gerald E. 1983. Ecological adaptations in Douglas-fir (Pseudotsuga menziesii var. glauca) populations. III. Central Idaho. Canadian Journal of Forest Research. 13: 626-632. Growth, phenology, and cold hardiness of seedlings from 74 populations of Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) from central Idaho were compared in four contrasting environments. Analyses of 3-year-old seedlings revealed population differentiation for eight variables: bud burst, bud set, multiple flushing, height, deviation from regression of 3-year height on 2-year height, spring...

The effects of brood parasitism by the dwarf race of the Brown-headed Cowbird (Molothrus ater obscurus) on the nesting success of the Abert's Towhee (Pipilo aberti) in the lower Colorado River valley were studied. The frequency of cowbird parasitism varied significantly with time of season. The laying season of cowbirds paralleled that of migratory songbirds, but began a month later than that of the sedentary Abert's Towhee. After an influx of breeding cowbirds, 44% of towhee nests were parasitized. Egg ejection by adult cowbirds caused towhee clutches to decline significantly from a...

Several meteorological variables are known to influence the heat budgets of nesting birds (e.g., Walsberg and King 1978a, b). Such factors include air temperature, incident radiation, wind, and humidity. If the microclimate of the nest is unfavorable, parent birds may become inattentive, exposing eggs or nestlings to excessive heat or cold. They may then desert the nest and their offspring may die. To improve the probability of nesting successfully, many Old World desert birds place their nests so as to receive morning sunlight (Maclean 1976). Several investigators have demonstrated...

Interprets changes in forest and range vegetation resulting from the absence of fire. Eighty-six matched photographs covering the period 1871-1982 provide the basis for describing how vegetation has changed in various plant communities. These scenes show that woody vegetation has increased markedly as a result of reduced wildfire. An increase in conifers and deterioration of herbs, shrubs, and deciduous trees is resulting in loss of habitat upon which early and midsuccessional wildlife species depend. Implications on wildlife and opportunities for use of cutting and prescribed fire to...

The 1983 Silviculture Workshop was held in Eugene, Oregon, and the Willamette National Forest. The purpose of the workshop was to review and discuss the requirements by laws, regulations, and Forest Service policy of the need for and uses of economic analyses in silvicultural program planning and development.