Treesearch

A computerized growth and yield model based on a variable density stand table projection system using 1-inch-wide diameter classes has been developed for projecting expected stand conditions in southwestern mixed conifer and ponderosa pine stands, including the effects of dwarf mistletoe. Stand management options include both even-aged and uneven-aged cutting methods.

I studied geographic variation in the foraging ecology of four breeding and four non breeding species in three oak (Quercus spp.) woodlands of California. Variations were evident for all species. Variations in tree-species use, foraging tactics, substrates, and behaviors were species-specific. For example, White-breasted Nuthatches (Sitta carolinensis) used tree species with different frequencies at each study area, although they specialized in where and how they foraged within a tree. The foraging behavior of Yellow-rumped Warblers (Dendroica coronata) varied little among study areas,...

We report an extra-pair copulation (EPC) in the Flammulated Owl (Otus flammeolus), the first in strigiforms, and document 21 cases of extra-range movements (ERMs) in this species. Extra-range movements occurred throughout nesting with both sexes participating: males anytime during nesting and females only after their young fledged. Males appear to make ERMs to gain EPCs and later to evaluate resources and the status of males in other areas, whereas females may be assessing the success of nests in adjacent ranges to judge the quality of potential future mates.

Flaming combustion in cribs of large woody fuels, thickness 5 cm or greater, is not sustained when fuel spacing ratio, fuel edge-to-edge separation distance to fuel thickness, is greater than 3:1. The flame length associated with the large-fuel burning rate was found to drop rapidly when the large-fuel spacing ratio increases beyond 2.23:1. This supports the critical spacing assigned in the large-fuel subroutine burnout of Albini's fire modeling program.

The marginal economic value of streamflow leaving forested areas in the Colorado River Basin was estimated by determining the impact on water use of a small change in streamflow and then applying economic value estimates to the water use changes. The effect on water use of a change in streamflow was estimated with a network flow model that simulated salinity levels and the routing of flow to consumptive uses and hydroelectric dams throughout the Basin. The results show that, under current water management institutions, the marginal value of streamflow in the Colorado River Basin is largely...

A meltwater ionic pulse with initial concentrations of 5-10 or more times the average was observed in lysimeters set at the base of a 2-m snowpack in an unpolluted, alpine watershed. Both background chemical species and added tracers exhibited the initial pulse. About 10 days after the onset of meltwater release, solute concentrations collected in the lysimeters dropped to near the average snowpack level. Silica was elevated more than major ions in some initial lysimeter samples, which is evidence of a soilwater or overland-flow contribution. Lysimeter flow rates were equivalent to about 2...

The Glacier Lakes Ecosystem Experiments Site (GLEES) is a high-elevation ecosystem in the Snowy Range west of Laramie, WY, that is perceived to be highly sensitive to changes in chemical and physical climate. Deposition of atmospheric chemicals to this ecosystem is, in part, governed by the wind pattern. The GLEES has numerous wind-swept areas where the coniferous vegetation growth pattern is characteristically wind deformed or krummholz. Studies conducted in 1988 determined direction and degree of wind deformation of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa)...

We have used five methods to estimate the snow water equivalent input to the Glacier Lakes Ecosystem Experiments Site (GLEES) in south-central Wyoming during the winter 1987-1988 and to obtain an estimate of the errors. The methods are: (1) the Martinec and Rango degree-day method; (2) Wooldridge et al. method of determining the average yearly snowfall from tree morphology; (3) precipitation gage measurements from the Wyoming Water Research Center Snowy Range Observatory; (4) NADP collector data; (5) an independent estimate from snow core data from a small catchment in the GLEES. Estimated...

Although a commercial growing medium with incorporated agricultural lime had been successfully used for years, it caused growth distortion of coniferous and deciduous seedlings during 1988. Seedlings grown in the amended medium were stunted and chlorotic, often with disfigured needles and multiple tops. Seedlings grown in the same medium without incorporated lime grew normally. These symptoms are attributed to a nutritional problem caused by dolomitic limestone in the medium.

The Pine Hollow aspen (Populus tremuloides) exclosures on the Ashley National Forest in eastern Utah were sampled in 1984, 19 years after they were established. The effects of 2,4-D, wildlife, and cattle on plant succession were evaluated. Two exclosures were used to protect the sprayed area from (1) all animal use and (2) only livestock use. A third sprayed area was left open for use by all animals. The aspen overstory was killed as a result of spraying, with sufficient reproduction occurring to restock the stand. However, animal use drastically altered the aspen reproduction, as well as...