Treesearch

Round posts of 10 Hawaii-grown wood species were treated with copper chromate-copper arsenate by the double-diffusion process. These and untreated posts were exposed for 10 years. Except with two coniferous species, the treatment did not lengthen service life enough to be judged worthwhile.

A computer method has been developed for simulating the combustion of wood and other cellulosic fuels. The products of combustion are used as input for a convection model that slimulates real fires. The method allows the chemical process to proceed to equilibrium and then examines the effects of mass addition and repartitioning on the fluid mechanics of the convection column in a fire.

The effects of non-grazing on Ahwahnee coarse sandy loam were studied at the San Joaquin Experimental Range in central California. An exclosure, on which there had been no livestock grazing for 34 years, had a lower surface bulk density and lower acidity than an adjacent range that had been grazed. Bulk density averaged 1.08 gm./cc. on the ungrazed range, and 1.43 gm./cc. on the grazed range. The pH values were 6.15 for the ungrazed area, and 5.65 for the grazed area.

Fourteen insecticides were evaluated for contact toxicity to 3rd and 4th stage pine butterfly larvae (Neophasia menapia F. & F.) in a laboratory spray chamber. All candidate insecticides except trichlorfon were more toxic than the standard DDT. The ranking of toxicity at LD90 and toxicity indexes (times more toxic than DDT) were: SBP-1382 (117), pyrethrins (62), Dowco 214 (22), methomyl (6.2), chlorpyrifos (6.2), Gardona (4.5), Sumithion (3.8), phoxim (2.8), Zectran (2.4), aminocarb (2.2), malathion (1.6), carbaryl (1.6), DDT (1.0), and trichlorfon (

A major browse plant in the central California foothills, wedgeleaf ceanothus (Ceanothus cuneatus) is used by a variety of animals. The canopy effect of the species was studied on the San Joaquin Experimental Range. Total herbage yield was not significantly affected by the canopy. But herbage yields of some individual species were affected by both the position in relation to canopy edge and the direction from a wedgeleaf ceanothus shrub. Range managers concerned about herbage yields will need to consider these effects.

This study presents observations on 15 pairs of White-crowned Sparrows (Zonotrichia leucophys nuttalli) breeding near Point Reyes Bird Observatory, Marin County, California, in the spring of 1969.

Timber RAM (Resource Allocation Method) is a long-range planning method for commercial timber lands under multiple-use management. Timber RAM can produce cutting and reforestation schedules and related harvest and economic reports. Each schedule optimizes an index of performance, subject to periodic constraints on revenues, costs, and, harvest levels. Periodic constraints can also be used to regulate forest stands and to even out the flow of timber during conversion. Schedules are calculated on computers by using linear programing techniques.

In a new approach, transmission was studied by relating to stand biomass the ratio of incoming solar radiation beneath tree crowns to that within the atmosphere. Several assumptions were used to estimate analytically the various ways in which solar radiation penetrates through crowns of three pine species in northern California. Sunflecks accounted for much of the radiation reaching the forest floor.

This publication brings together 57 elevational profiles illustrating the dominant vegetation of much of the Sierra Nevada, southern Coast Ranges, and montane southern California as it existed in the 1930's. The profiles were drawn by Michael N. Dobrotin for the U.S. Forest Service's Vegetation Type Map survey, which mapped nearly half of the State's vegetation. Besides providing a historical record, the profiles illustrate the influence of such ecological factors as elevation, exposure, and slope on the composition of the dominant vegetation.

Accident hazard associated with trees on recreation sites is inherently concerned with probabilities. The major factors include the probabilities of mechanical failure and of target impact if failure occurs, the damage potential of the failure, and the target value. Hazard may be evaluated as the product of these factors; i.e., expected loss during the current inspection cycle unless hazard is reduced. A practical approach to hazard rating is described. Tables on damage potential for recreationist occupancy and for fixed property are included in the field guide.