Treesearch

We evaluated the ability of discriminant analysis (DA), logistic regression (LR), and multiple regression (MR) to describe habitat use by amphibians, reptiles, and small mammals found in California oak woodlands. We also compared models derived from pitfall and live trapping data for several species. Habitat relations modeled by DA and LR produced similar results, averaging about 70% classification success of the trapping stations to the correct group (capture or noncapture habitat). Although more variables were included in DA (4-5) than in LR (2-3), those included in LR were typically a...

Estimating empirical measures of an individual's willingness to accept that are consistent with conventional economic theory, has proven difficult. The method of paired comparison offers a promising approach to estimate willingness to accept. This method involves having individuals make binary choices between receiving a particular good or a sum of money. Willingness to accept can be inferred from the ranking of dollar amounts and the good of interest. Using the paired comparison approach, mean (median) willingness to accept for a private good is estimated at $59($52). Contingent valuation...

A hierarchical framework for the classification of Great Basin pinyon-juniper woodlands was based on a systematic sample of 426 stands from a random selection of 66 of the 110 mountain ranges in the region. That is, mountain ranges were randomly selected, but stands were systematically located on mountain ranges. The National Hierarchical Framework of Ecological Units (ECOMAP) was used for the highest levels of classification, subdividing the Great Basin into nine relatively environmentally homogeneous Sections. The remaining levels are vegetation-based, focusing on the relative composition...

Residential losses associated with wildland fires have become a serious international fire protection problem. The radiant heat flux from burning vegetation adjacent to a structure is a principal ignition factor. A thermal radiation and ignition model estimated structure ignition potential using designated flame characteristics (inferred from various types and densities of vegetation) and flame-to-structure distances. Model results indicate that ignitions from flame radiation are unlikely to occur from burning vegetation beyond 40 meters of a structure. Thinning vegetation within 40 meters...

Global Positioning System (GPS) units were used to record hunter locations at 15 second intervals during elk hunting expeditions. This information allowed us to examine the influence of roads on hunter behavior, and along with associated time and distance data, provide a solid foundation on which a hunter density and elk vulnerability model can be developed.

To better understand the habitat relationships of the Mexican spotted owl (Strix occidentalis lucida), and how such relationships might influence forest management, we studied home-range and habitat use of radio-marked owls in ponderosa pine (Pinus ponderosa) Gambel oak (Quercus gambelii) forest. Annual home-range size (95% adaptive-kernel estimate) averaged 895 ha plus/minus 70 (SE) for 12 individuals and 997 ha plus/minus 186 (SE) for 7 pairs of owls. On average, the 75% adaptive-kernel contour (a probability contour containing 75% of the owl locations) included 32 and 30% of the annual...

Despite a history of oak clearing and thinning in California, little is known about the effects of firewood harvesting on wildlife in oak woodlands. We studied the effect of firewood harvesting on population trends of birds during the breeding season in an oak-pine woodland in the foothills of the northern Sierra Nevada, California. During fall-winter of 1993-94, total tree basal area on 30 3.1-ha study plots was reduced by approximately 23% via removal of commercial-grade oaks, but all old-growth trees and trees with obvious nest cavities or woodpecker granaries were preserved. An...

This document is the product of an ongoing effort begun at a 4-day workshop sponsored by the Rocky Mountain Region of the USDA Forest Service, held in December 1990 in Estes Park, Colorado. Workshop participants gathered in groups to work on pollution impacts in three specific areas: aquatic ecosystems; terrestrial ecosystems; and visibility. Because the groups met separately and subsequently worked independently, the reports they generated differ considerably in format and style. They all focus, however, on providing the Forest Service with information that may be used to identify and...

Numbers of brown-headed cowbirds ( Molothrus ater) are increasing in some regions of North America, while certain populations of long-distance, neotropical migratory songbirds (NTMs) are declining. In the Southwestern United States, several species of NTMs nest only in riparian habitats. The significant decline of two species of NTMs dependent upon riparian habitat, the southwestern willow flycatcher ( Empidonax traillii extimus) and the least Bell's vireo (Vireo bellii pusillus), is of great concern. Brood parasitism by the brown-headed cowbird and loss of riparian habitat may be the...

Many managers face the challenge of monitoring rates of visitor encounters in wilderness. This study (1) provides estimates of encounter rates through use of several monitoring methods, (2) determines the relationship between the various measures of encounter rates, and (3) determines the relationship between various indirect predictors of encounter rates and actual encounter rates.Exit surveys, trip diaries, wilderness ranger observations, trained observers, mechanical counters, trailhead count observations, and parking lot vehicle counts were used to develop better understanding of the...