Treesearch

The possible harmful effect of insecticides on nontarget organisms should be a prominent concern in all attempts to control forest pests. Although all wildlife must be considered, birds are particularly vulnerable. The study reported here was part of the effort to find an environmentally safe method to control one of the major sources of insect damage to forest trees - the Douglas-fir tussock moth (Orgyia pseudotsugata [McDunnough]). Its larval stage is an important defoliator of true firs (Abies sp.) and Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco)in western North...

Orthene was tested in a randomized block experiment to determine efficacy against larch casebearer. Needlemining larval populations were sprayed in September 1976 by helicopter with 0.5 lb Orthene/gal water/acre (560 g a.i/9.3 l/ha). Spray deposit was sampled with Kromekote cards. Plot mean larval populations, spray deposit, and defoliation index were analyzed to detect significant differences among treatments by using twoway analyses of variance. Larval populations were reduced an average of 92.1 percent on the nine treated plots and an average of 40.5 percent on the three check plots....

In stands of mixed white and red fir in northeastern California, cuttings for natural regeneration became well stocked with seedlings within 2 to 5 years after cutting. Seed tree and shelterwood cuttings, clearcut strips not more than 3 chains (60 m) wide, and patches not exceeding 4 chains (80 m) width were studied. Incidence of damage among residual trees in or adjacent to cuttings was negligible. Low vegetation developed slowly and did not appear to affect seedling survival.

Growth was analyzed after one thinning in a plantation of pole-size ponderosa and Jeffrey pines on land having a site index of 50 feet at 50 years. Periodic annual increment was determined for each of three 5-year periods. On this basis, increment in diameter and cubic volume were found to he related closely to stand basal area only. Basal area and height increment, however, were also related to time since thinning: basal area growth decreased and height growth increased with each succeeding period. The optimum basal area for volume production (both cubic and board-foot measures) was...

Snow is a major source of water in Western United States. Data on snow depth and average snowpack density are used in mathematical models to predict water supply. In California, about 75 percent of the snow survey sites above 2750-meter elevation now used to collect data are in statutory wilderness areas. There is need for a method of estimating the water content of a snowpack in inaccessible locations by remote means. If snow albedo can be measured from aircraft and these measures correlated with snowpack density, we should be able to estimate density remotely. But a correlation must...

Release cutting, live crown ratio, diameter-at-breast height, and dwarf mistletoe (Arceuthobium abietinum f. sp. magnificae). acted to affect radial and height growth of red firs (Abies magnifica A. Murr.). Infected and noninfected red firs responded well to release as expressed by increased radial growth: growth rate doubled within 10 years after release. Live crown ratio also had a marked effect on radial growth rate. Irrespective of the level of dwarf mistletoe, trees with good live crown ratios showed significantly greater rates of radial growth than did trees with poor live crown...

A telephone survey of 1500 households in metropolitan Los Angeles and San Francisco was made to (1) determine extent of wildland use by residents of the two metropolitan areas, reasons for non-use, and the characteristics of users; (2) describe and analyze activities, knowledge, and attitudes of users which may contribute to their fire risk; and (3) assess selected communication channels for conveying forest fire prevention information to the residents of metropolitan areas. Wildland use was more prevalent among San Francisco households, but otherwise households in the two areas were...

In tests on the Bitterroot National Forest, Montana, in 1965 and 1966, mexacarbate, aerially applied at the rate of 0.15 lb a.i./gal/acre (68.04 g a.iJ3.785 1/0.404 ha), killed about 90 percent of the western spruce budworm (Choristoneura occidentalis Freeman) populations. More parasitized budworm larvae survived treatments than nonparasitized. Apanteles fumiferanae Viereck and Glypta fumiferanae Viereck-two overwintering parasites-and Phaeogenes hariolus (Cresson), Mesochorus sp., and tachinids-late larval, pupal parasites-increased following treatments. But parasites tended to return to...

Growth was strongly related to growing stock level (GSL) for 5 years after thinning 20-year-old poles on Site Index50 115 land at the Elliot Ranch Plantation in northern California. Five GSL's-basal areas anticipated when trees average 10 inches d.b.h. or more-ranging from 40 to 160 square feet per acre were tested. Periodic annual increment (PAI) in diameter ecreased curvilinearly from 0.51 to 0.21 inch, with increasing GSL's from 40 to 160. But only trees in plots heavily thinned to GSL 40 (and briefly in GSL 70) grew faster in diameter after thinning than these same trees grew before...

A survey of 61 cutblocks planted since 1964 evaluated stocking of conifers (trees 1 foot tall or taller) on 2-milacre quadrats. Overall stocking percentage averaged 42.2 and ranged from 15 to 8 1. Overall number of trees per acre averaged 396. In the regression model, based on 36 cutblocks, better stocking was associated with high site class, northerly aspect, elevation below 3000 feet, and tractor (rather than cable) logging. Stocking tended to increase with increasing age of plantation, but decreased with increasing size of cutblocks.