Treesearch

Ten chemicals representative of four insecticide groups (earbamate, organophosphate, chlorinated hydrocarbon, and pyrethroid) were applied topically to mixed groups of 5th- and 6th-stage larvae of Malaeosoma californicum califomicum (Packard). Only 2&emdash;the pyrethroid NIA 24110 ((5-benzyl-3-furyl) methyl trans-( +)-3-(cyclopentylidenemethyl)-2,2-dimethylcyclopropanecarboxylate), and resmethrin-were more toxic than DDT at LD50. Because of the low slope of DDT, however, 8 insecticides exceeded it in toxicity at LD90. These were, in decreasing order of toxicity, NIA 24110, resmethrin,...

Coppicing provides a method of converting cull sapling and pole-size Australian toon (Toono australis) and tropical ash (Fraxillus uhdel) trees to "acceptable trees." In trial plots on the island of Hawaii, stumps of both species sprouted, resulting in a high percentage of vigorous, well-formed sterns. Codominant stems on the stump must be thinned to prevent multiple-stemmed trees. Converting Australian toon was a two-step operation: (1) cut off the original stem, and (2) cut off all but the dominant sprout in each stump. Converting tropical ash required an additional step: cut off all...

Firetree (Myrica faya), an aggressive plant pest without any commercial value, has infested thousands of acres of forest and range lands in Hawaii. Methods of controlling it must be found if these lands are to be planted to more desirable species. In a study on the island of Hawaii, various combinations of Tordon 212 herbicide, injected into knotches cut at intervals around a tree, and month of treatment were tried. None of the combinations tested was effective in controlling firetree.

Ponderosa pine progenies from parents restricted in latitude but spanning 7.000 feet of elevation show significant growth differences in plantations at low-, mid-, and high-elevation test sites. At low- and mid-elevation sites tree heights and diameters of progenies from high-elevation parents were the smallest; those from the low-elevation parents, intermediate; and those from mid-elevation seed parents, largest. At the high elevation site, trees from mid- and high-elevation sources grew equally well, whereas trees from low-elevation parents showed poorest growth. The variation associated...

Tracheid lengths in 30-year-old ponderosa pine progeny test plantations in the central Sierra Nevada of California were analyzed for effects of (a) elevation of seed parents and (b) elevation and location of test sites. The influence of elevation of seed parents on progeny tracheid length was not significant. Plantation location was significant, but interaction between progeny and location was not. The regression of tracheid length on dbh was negative. Regardless of elevation of parent source, high-elevation plantings produced larger diameters and shorter tracheids than lower elevation...

A method has been devised for producing high-quality black-and-white negatives quickly and efficiently from dense transparencies orgininating from Earth Resources Technology Satellite imagery. Transparencies are evaluated on a standard light source to determine exposure and processing information needed for making negatives. A “System ASA Rating” was developed by testing and selecting combinations of film, light sources, and developer. Changes in film density and contrast of negatives owing to reciprocity effects are controlled by calculating adjustments in exposure and development. The...

Round posts of ohia and robusta pressure-treated with one of two preservatives are being tested for durability at the Makiki Exposure Site, Honolulu, Hawaii. After more than 10½ years, all posts treated with pentachlorophenol are still sound. And all but one robusta post treated with chromated copper aresenate are still sound. Life of untreated posts of both species average about 4 years. Decay was the cause of failure.

The Fire Environmental Test Chamber at the Forest Fire Laboratory, Riverside, California, can duplicate under controlled conditions the key factors that affect the flammability of wildland fuels. Within certain limits, it can produce air flow, solar radiation, temperatures, and relative humidity. First developed in 1962, the test chamber has since then undergoneseveral modifications to meet requirements over and above the original capabilities. The characteristics of the test chamber and nature of the changes are explained. Recommendations on design and development are offered.

The volume of lumber and plywood products used in apartment construction in California was estimated from a sample of apartments for which architectural plans were completed in 1969. Excluding wood mouldings, doors, cabinets, and shelving, an average of 4.85 board feet of lumber and 2.03 square feet (318-inch basis) of plywood per square foot of floor area were used in the 17 structures studied. The ability of wood to meet fire and seismic standards at the least cost was the factor cited most often for its use. The outlook for wood in future apartment construction will probably depend...

Bands of shorthair meadow are found around lakes in the high Sierra Nevada of California. A hypothesis, based on observations in the Kings Canyon National Park, to explain the development of these meadows is offered: Boulders form the foundation upon which American-laurel, Sierra bilberry, and moss combine to produce thick mats. The lower layers of the mats are gradually converted to acid bog or mucksoil, which becomes in effect the C horizon of soil supporting the shorthair meadow type. Herbaceous plants change the upper layers and, thereby, produce an A horizon and a succession leading...