Treesearch

For nearly 50 years, effluents from pulp and paper mills have been known to be toxic to fish and other aquatic animals. Lethal concentrations have been determined for several species of fish and other organisms. Many factors- -such as water temperature, age of fish, and additional stresses—affect the ability of fish to withstand pollution. Kraft mill wastes are generally more toxic than sulfite wastes. The high biological oxygen demand of sulfite wastes is often more serious than the chemical toxicity of the effluents. Studies on the effect of kraft effluents on invertebrates show...

In the absence of prices for nonmarketed outdoor recreational services provided by public agencies, it is not possible to do a complete benefit cost analysis for proposed facilities for recreation. Good information on the cost of providing recreational services to the public is nonetheless important. This paper provides a step-by-step procedure that recreation planners can use to estimate the cost per user-day for proposed recreational facilities.

The 10-year growth of a 55-year-old, even-aged western larch (Larix occidentalis Nutt.) stand after it was thinned from above and below to a wide range of stocking levels was measured in eastern Oregon. Basal area and volume growth increased as stand density increased for both thinning methods. Despite heavy infestations of the larch casebearer during the last 4 years, diameter growth was greater in the second 5-year period than the first, but height growth was reduced considerably because of top dieback. Thinning from above reduced net volume growth because of mortality caused by windthrow...

The tri-tube cryogenic gravel sampler has been improved, and accessories have been developed that increase its reliability and safety of operation, reduce core extraction time, and allow accurate partitioning of cores into subsamples. The improved tri-tube sampler is one of the most versatile and efficient substrate sampling tools yet developed.

The population response of the northern red-backed vole (Clethrionomys rutilus) to a differentially cut white spruce (Picea glauca) forest 30 km southwest of Fairbanks, Alaska, was monitored by simultaneous livetrapping in a clearcut, in a partially cut or shelterwood area, and in an area of uncut forest. During the first summer after logging, vole density was similar in the shelterwood and uncut forest, but lower in the clearcut. Breeding occurred in all areas, and only overwintering females had litters. Movement between areas was minimal. Populations in all areas were similar in age and...

A possibly new species or subspecies of larch bud moth of the genus Zeiraphera, closely related to Z. improbana (Walker), was found associated with tamarack, Larix laricina (Du Roi) K. Koch, stands in interior Alaska. An outbreak occurred during 1975 and 1976 over an area of 240 000 ha (590,000 acres). Adult moths were mottled grayish in appearance. First instars emerged from the overwintering egg stage from mid to late May and began feeding as soon as the tamarack buds began to unfold. Pupation, adult emergence, and oviposition occurred from mid-June to mid-July and there was one generatio...

With some exceptions, the substitution of national forest timber for exported private timber is forbidden by regulations. Certain firms may use a limited amount of national forest timber as replacement for exported private timber, however, in accordance with their pattern of purchases and exports from 1971 through 1973. About 359 million board feet of national forest timber could be used annually as replacement for exported private timber by this provision; in 1977, about 102 million board feet was used in this fashion. About 81 percent of the replacement volume was from national forests...

One-year-old western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedlings from three open-pollination families from eight locations in the Washington and Oregon Coast Ranges were cultured under accelerated growth conditions in a glasshouse. Forty cuttings from each of five seedlings (open-pollination siblings) per family were then placed in a rooting box in a randomized block design with five replications. Percentages of cuttings rooted after 1 year in the bed were analyzed in a hierarchal design. Average rooting percentage was 72.4 percent. Significant effects were associated only with...

Low-elevation seeds collected 6 and 2 weeks before assumed natural seed fall were stratified 1, 2, 4, 8, 16, 32, 64, and 123 days and germinated in the laboratory. Germinated seeds from all stratification periods were sown at the same time in the nursery bed. Germination and seedling measurements were taken over two growing seasons. Early collection gave smaller seeds, reduced germination percentage, and yielded smaller seedlings. Reduced seedling size appeared to be related to reduced seed weight. Germination rates of both early- and late-collected seeds increased with increased stratifica...

The 2- and 5-year diameter and height growth of suppressed grand fir (Abies grandis (Dougl. ex D. Don) Lindl.) advance reproduction was measured in central Oregon after the overstory was removed. Multiple regression analyses were used to predict growth response as a function of individual tree variables. The resulting equations, although highly significant, explained only 17 to 44 percent of the variation in growth. Live crown ratio gave the best single variable correlation for both diameter and height growth. Height growth after release was similar to growth before release. Only vigorous...