Treesearch

Twenty insecticides were tested by topical application on mixed groups of 4th- and 5th -stage larvae of Symmerista canicosta Franclemont. Four exceeded DDT in toxicity at LD50 but only resmethrin was significantly mor toxic. Most of the compounds showed unusually high toxicities. Twelve, listed in decreasing order of toxicity, caused 50% mortality with <5μg/g body weight: resmethrin, methonmyl, phoxim, pyrethrins, DDT, Zectran (4-dimethylamino-3.5-xylyl methylcarbamate), chlorpyrifos, Landrin (3,4,5- (93%) and 2,3,5-trimethylphenyl methylcarbamate (7%)), Gardona (2-chloro-1-(2,4,5-trichloro...

Standing crops of juvenile coho (silver) salmon (Oncorhynchus kisutch), steelhead rainbow trout (Salmo gairdneri), and coast cutthroat trout (Salmo clarki) were examined in seven coastal streams to define the natural carrying capacity of these streams, and to develop methods of population comparison and prediction which could be used to determine the effects of road construction and logging on salmon and trout production.

Young-growth ponderosa pine seed trees were evaluated in terms of seed production. Seed trees ranging from 3 to 9 per acre produced 5,000 to 35,000 seeds per acre in years of moderate and heavy cone crops. Seed-tree selection before harvesting by the seed-tree method of cutting must be keyed to evidence of past cone production to assure best seed production in the future.

Water quality was monitored in 1968 and 1969 in six coastal streams in northern California, four of which were subjected to logging and/or road building (Bummer Lake Creek, South Fork Yager Creek, Little North Fork Noyo River, and South Fork Caspar Creek), while the others remained undisturbed (Godwood Creek and North Fork Caspar Creek). The purposes of this study were to characterize the water quality of the streams, to determine if the logging and road construction drastically altered water quality, and to collect water quality data which could be tested for predicting stream carrying...

Leaflike samples, approximately 8 cm in diameter, are held at the end of a mechanical arm which reproducibly controls sample movement during the ignition and burn ing process. Glowing combustion is induced by bringing the sample into contact with a small loop in an electrically heated nichrome wire. The ultimate burned-out area is measured 1n an ultraviolet detection system utilizing a vacuum photodiode. The system, calibrated using black construction paper with a series of standard holes in the range 0.002 to 20 cm2, has a sensitivity close to 5 mv/cm2.

By providing continuous weight measurement, thermogravimetry, even for isothermal experiments, offers a major advantage over the classical methods of determining weight-change curves in complex pyrolysis reactions. Thus, even minor weight changes, readily detectable on a continuous record, furnish clues concerning the reaction sequences and indicate conditions under which confirmatory experiments may be undertaken. Unfortunately, such perturbations are frequently ignored, being considered part of the "experimental error" which they often represent in the traditional experiments. This paper...

The conversion of brush areas to grassland increased soil slip erosion on mountainous watersheds in southern California during the intense winter storms of 1969. The incidence of soil slippage, site factors affecting slope stability, and amount of debris generated by slippage were investigated for sample brush and grass areas in the San Dimas Experimental Forest. Soil slippage occurred on 5.5% of the brush areas and 16.7% of the grass areas, the values for both areas being about twice those measured in 1966 for a less intense storm period. The effectiveness of linear discriminant analysis...

In the Marin County hills just 25 miles north of San Francisco, Calif., the small town of Nicasio looks much like it did a century ago ... a quiet community of some 500 people, surrounded by rolling grass-covered hills and wooded canyons.

Future crown class may be determined well in advance of intertree competition in plantation grown ponderosa pine. Regardless of site quality, dominant trees in 10 California plantations reached breast height ½ year sooner than codominants and 1-½ years sooner than intermediates. Dominant trees on poor sites reached breast height several years earlier than has been reported for natural stands. Failure to recognize this rapid early growth will result in underestimating site index in plantations. Relative height is recommended as a guide in marking thinnings or Christmas tree cuttings.

Recreationists or city dwellers are usually most often thought of as being responsible for starting forest fires. But a limited study showed that fire starters were more apt to be people who lived near and worked on the National Forests. They were relatively young and undereducated, and had "good reputations" in their communities. Employers held responsible for forest fires started by their employees most often had multiple fire violations, but "good reputations" in their communities. These and other characteristics of fire-starters were identified by analyzing 165 Fire Trespass Reports...