Treesearch

Effects of predaceous birds and ants on the western spruce budworm, Choristoneura occidentalis, were studied on seedlings of western larch and Douglas-fir in western Montana. On western larch, both birds and ants reduced survival of larval budworm (instars IV-VI). On Douglas-fir, larval survival on one site was reduced by ants but not by birds. On a second site, neither birds nor ants had any effect on larval survival on Douglas-fir. Ants, but not birds, continued to have a major effect on the survival of budworm pupae.

The exchange of information among invertebrate pathologists of the major linguistic areas of Western Europe and North America has created a demand for a multilingual glossary. This list of specialized terms used in invertebrate pathology and related fields, such as microbial control, comprises over 2200 entries gathered by the four authors with the help of several consultants. As many synonyms as could be found in past or current use have been listed and cross-referenced in each of the five languages. This glossary is a valuable tool for computerized searches of literature data bases, for...

Old-growth, western hemlock-Sitka spruce forest in southeastern Alaska is an important element of the habitat of Sitka black-tailed deer. The conversion of uneven-aged, old-growth forests to even-aged, second-growth forests has generated concern about the future carrying capacity of the habitat for deer, especially where snow accumulation is common on winter ranges. Even-aged, second-growth forests produce very little forage for black-tailed deer. Young(< 20 years), open stands produce greater amounts of forage than do old-growth stands. Snow accumulates to greater depths in openings than...

A sample of 133 Douglas-firs (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and 69 true firs (Abies spp.) with dead tops caused by defoliation by the western spruce budworm (Choristoneura occidentalis Freeman) were felled, dissected, and examined for height loss and incidence and extent of decay. Height loss was negligible for trees with only the last year or two of their tops killed by defoliation because lateral branches quickly formed new tops. Height losses of trees severely damaged by top-kill averaged 4.3 feet for Douglas-fir and 4.4 feet for true firs, but some trees had new...

Quantities of coarse and fine organic debris in streams flowing through areas clearcut before 1975 are 3 and 6 times greater than quantities in streams sampled in old-growth stands in Tongass National Forest, central Prince of Wales Island, southeast Alaska. The concentration of debris in streams of clearcut Sitka spruce-western hemlock forests in southeast Alaska, however, is about half that in streams of clearcut Douglas-fir western hemlock forests in western Oregon. Management guidelines for maintaining natural debris conditions include minimizing the addition of fresh material to a...

Logging cost equations are provided that can be used for analyses of silvicultural regimes. These equations include costs for all phases of logging from felling to loading onto a truck. They are presented by various components so that the user can substitute other values if some components do not seem applicable. Where appropriate these costs vary by size of trees harvested and volume removed at a logging entry. It is especially important that these cost relationships be reflected in logging costs used in evaluations of silvicultural regimes because the evaluations will otherwise be biased...

Site preparation techniques to aid establishment of fourwing saltbush (Atriplex canescens) were compared at a test location in eastern Oregon. Survival and growth of transplanted seedlings were improved after one season of growth by either spot spraying with herbicides or scalping to reduce competing vegetation. Average growth of seedlings was greater with the spray treatment than with scalp treatment. Control of plant competition should improve transplanting success of fourwing saltbush in many related rangeland areas.

This initial study of prescribed burning in ponderosa pine (Pinus ponderosa Doug. ex Laws.) stands in central Oregon showed that all periodic annual growth increments were reduced for trees alive four growing seasons later. Height growth was reduced 8 percent in areas burned by fires with moderate fuel consumption and 18 percent in areas with high fuel consumption. Basal area growth was reduced 16 percent in the moderate fuel consumption areas and 28 percent in the high fuel consumption areas; volume growth declined 23 percent at both levels of fuel consumption. Foliar nitrogen (N)...

The performance of the Bergstrom xylodensimeter, designed to measure the green density of wood, was investigated and compared with a technique that derived green densities from wood disk samples. In addition, log and bole weights of old-growth Douglas-fir and western hemlock were calculated by various formulas and compared with lifted weights measured with a load cell attached to a front-end loader. The Bergstrom xylodensimeter accurately measured green wood density and is useful for estimating log weights.

A sample of 351 ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and 509 lodgepole pine (Pinus contorta Dougl. ex Loud.) logs were used to evaluate the performance of three commonly used formulas for estimating cubic volume. Smalian's formula, Bruce's formula, and Huber's formula were tested to determine which would provide the best estimate of cubic volume when it was applied to tree-length logs. Smalian's formula overestimated the volume by 19 percent, Bruce's formula underestimated by 16 percent, and Huber's formula underestimated by 2 percent. Huber's formula provided the closest...