Treesearch

Anthropogenic activities of the past century have caused a dramatic increase in global air pollution. This process has accelerated in the past few decades, and emissions of carbon dioxide, nitrogen oxides, or chlorofluorocarbons caused serious changes in the earth's climate, e.g., increased temperatures or elevated ultraviolet-B radiation. These changes, together with more severe droughts, forest fires, and air pollution (ozone, nitrogen or sulfur compounds), may have pronounced effects on terrestrial ecosystems. Changes in global and regional carbon and nitrogen cycles as well as changes...

Although fungal fruiting bodies are a common food supplement for many forest animals and an important dietary staple for several small mammals, changes in their abundance and consumption with forest succession or disturbance have not been quantified. Above- and belowground fungal fruiting bodies (epigeous and hypogeous sporocarps) were sampled for 46 mo in managed-young, natural-mature, and old-growth western hemlock (Tsuga heterophylla) stands in Washington State. Screen exclosures were placed over the surface of half of the sample plots to prevent aboveground predation of sporocarps....

Specimens representing 19 orders and 169 arthropod families (mostly insects) were collected from greenleaf manzanita brushfields in northeastern California and identified to species whenever possible. More than500 taxa below the family level were inventoried, and each listing includes relative frequency of encounter, life stages collected, and dominant role in the greenleaf manzanita community. Specific host relationships are included for some predators and parasitoids. Herbivores, predators, and parasitoids comprised the majority (80 percent) of identified insects and related taxa.

We present a statistical procedure for studying the simultaneous effects of observed covariates and unmeasured spatial variables on responses of interest. The procedure uses regression type analyses that can be used with existing statistical software packages. An example using the rate of twig beetle attacks on Douglas-fir trees in a seed orchard illustrates the problem and the recommended statistical procedures. Use of this procedure revealed spatial patterns in beetle attacks that were not otherwise evident. We also found that the covariates, tree vigor, cone crop, and host genotype...

Wind velocity and slope are two critical variables that affect wildland fire rate of spread. The effects of these variables on rate of spread are often combined in rate-of-spread models using vector addition. The various methods used to combine wind and slope effects have seldom been validated or compared due to differences in the models or to lack of data. In this study, rate-of-spread predictions from the Canadian Fire Behavior Prediction (FBP) system, McArthur's Mark V forest fire danger meter, the Rothermel empirical model, and the Pagni and Peterson physical model were compared with...

On an above-average site in northern California, a complex plant community was treated by manual release in 2- and 5-foot radii, one and three times. Mulching with a small (3-footsquare) paper / asphalt mulch and a control were additional treatments. Results for a 10-year period are presented for shrubs, a subshrub (whipplea), ferns, forbs, and grasses. No single category of competing vegetation dominated during the study, and competition to planted ponderosa pines was from all vegetation combined. In spite of large amounts of competing vegetation, the pines dominated in all trials,...

Abstract - Weight change in age-0 coho salmon, Oncorhynchus kisutch at about natural density was negatively related to the density of juvenile steelhead (anadromous rainbow trout O. mykiss) in a 6-week experiment conducted in July-August 1993 in the north and south forks of Caspar Creek, California. The experiment used 12 enclosed stream sections, each containing a pool and a portion of upstream riffle, with two replicates of three steelhead densities-zero, natural density (1X), and twice the natural density (2X)-on both the north and south forks. The natural density of coho salmon was...

Abstract - The old-growth redwood forest of North Fork Caspar Creek was clear-cut between 1864 and 1904. Previous research on logging-related changes in suspended sediment and streamflow would suggest that North Fork Caspar Creek has recovered from historical logging (Rice et al., 1979; Ziemer, 1981); research on the influence of large woody debris (LWD) on channel form and function would suggest it has not (Sedell and Luchessa, 1982; Keller and Tally, 1979). I developed a sediment budget for mainstem North Fork Caspar Creek for water years (WY) 1980-1988 to evaluate controls on sediment...

The dense coniferous forests of the North Coast Range of California have been harvested for valuable redwood (Sequoia sempervirens), Douglas fir (Pseudotsuga menziesii), and other tree species for more than 100 years. Initially, the primary focus of logging activities was to efficiently fall the trees and transport them to the mill site without much concern for the sustained productivity of the renewable forest resource and other environmental components within the drainage basin. However, for some time now, it has been recognized that logging activities can have significant impacts, both...