Treesearch

The segmented polynomial stem profile model of Max and Burkhart was applied to seven tree species in the Rocky Mountain Region of the Forest Service. Errors were reduced over the entire data set by use of second-stage models that adjust for transformation bias and explained weak patterns in the residual diameter predictions.

The profile model of Max and Burkhart was fit to eight tree species in the Pacific Northwest Region (Oregon and Washington) of the Forest Service. Most estimates of merchantable volume had an average error less than 10% when applied to independent test data for three national forests.

A model for calculating daily microclimate conditions in mountainous terrain is presented. Daily air temperature, shortwave radiation, relative humidity, and precipitation are extrapolated form data measured at National Weather Service stations. The model equations are given and the paper describes how to execute the model. Model outputs are compared with observed data from several mountain sites.

Twelve-year postharvest diameter growth of advance Douglas-fir, Engelmann spruce, and subalpine fir regeneration and 11-year height growth of Douglas-fir and subalpine fir accelerated in response to decreasing competition. Competition was reflected in degree of overstory removal and change in plot basal area. Notwithstanding the influence of change in competition, the most influential variable affecting postharvest height and diameter growth was 10-year radial growth prior to overstory removal; trees growing well before harvest grew well after harvest. Postharvest mortality was greatest...

Measurements of 3rd-year height of 228 seedling populations, grown in four separate studies in two of the same common gardens, were used to summarize patterns of genetic variation for Douglas-fir across 250 000 km 2 of forested lands in Idaho and Montana, U.S.A. Because each study was conducted in different years with a different set of populations, measurements were transformed to standard deviates and then were scaled according to the performance of populations common between studies. Genetic variation in 3rd-year height was related to the elevation and geographic location of the seed...

Selected forage species were sampled during the first and second summers after autumn prescribed burning of three sites in southeastern Idaho. They were analyzed for in vitro dry matter digestibility, protein, calcium, and phosphorus. This aspen type has a highly nutritious understory. Burning further improved the quality of the selected species only during the first postburn summer. Burning, however, changed species composition from shrubs to an abundance of palatable and nutritious forbs.

This paper reviews opportunities and watershed restoration techniques available for rehabilitating and enhancing riparian ecosystems in southwest environments. As such, it is intended to serve as a state-of-the-art report on riparian hydrology and improvement in both naturally occurring and man-made riparian areas throughout the Southwest.

I investigated trends in bird species populations, guild structure, and bird communities along a riparian altitudinal cline in the Medicine Bow National Forest of southeastern Wyoming. Streamside habitats were divided into three elevational zones: low-elevation (2050 to 2260 m) cottonwood zone, mid-elevation (2290 to 2530 m) mixed shrub willow zone, and high elevation (2590 to 2990 m) subalpine willow zone. Vegetational complexity decreased from low to high zones, with loss of vertical habitat layers and increased foliage density and dominance of dwarf willows. Ground and lower-canopy...

The Fourth Biennial Wildlife Symposium was held at the historic Hotel Colorado in Glenwood Springs, Colorado, from February 6-8, 1989. In spite of some very cold wcather, the attendees came from many parts of the United States and Canada. As in previous years, they represented government, industry, academic and professional organizations, including nonprofits. Thorne Ecological Institute, with the co-sponsorship of several members of industry and other fine groups, is most pleased to present these Symposia every two years. They draw together biologists, wildlife managers and administrators...

I assessed relationships among habitat structure, nest-site selection, and reproductive outcome of House Wrens (Troglodytes aedon) by establishing three nest-box grids in riparian woodlands in southeastern Wyoming. Over a 3-year period, 37% of the boxes contained House Wren nests; 20% contained unused nests built by male House Wrens; and 42% were never used by wrens. Direct discriminant analyses separated three box-use groups (unused, 1-year use, 2- to 3-year use) and three nesting outcome possibilities (failure all years, 1-year success, 2- to 3-year success) along gradients of habitat...