Treesearch

Cytospora abietis was commonly found associated with dwarf mistletoe (Arceuthobium campylopodum f. sp. abietinum) parasitizing branches of white fir (Abies concolor) and red fir (A. magnifica). Twenty-two per cent of all branches bearing dwarf mistletoe were infected by C. abietis. Of 235 isolates of the fungus, only 9 (4%) were from branches not invaded by dwarf mistletoe. Both white and red fir are equally susceptible to infection by C. abietis. Geographic location in California and age of dwarf mistletoe were not important factors influencing infection by C. abietis.

Seven men skilled in fire research were stationed around the periphery of Flambeau Fire 760-12 and recorded visual impressions of its magnitude. Also, instrumental data were taken both inside the fire zone and outside, so that visual magnitudes of the mass fire may be compared with its measured physical parameters. Visual magnitudes for this fire were: Flame heights up to 300 feet, horizontal flames 100 feet; thermal radiation uncomfortable at 75 feet; able bodied men might escape from center of fire; cap cloud at 3000 feet; streets filled with smoke; fire whirls lifted bushes 100 feet;...

Mixed-conifer stands at the Challenge Experimental Forest, Calif., were cut to four specifications: seed-tree, group selection, single tree selection, and clearcut. Logging costs and production rates were compared and evaluated. Cutting method had little effect on felling or skidding production; felling ranged from 1,802 to 2,019 bd ft per hour, and skidding from 3,138 to 3,761 bd ft per hour. Felling cost $3.86 per M bd ft and skidding averaged $4.57. Loading production was 5,286 bd ft per hour and averaged $2.72 per M bd ft. It varied greatly with the number of logs per load; for...

After ponderosa pine seed trees were removed on the Challenge Experimental Forest, California, seedling stocking fell by 3.8 percent or about 212 seedlings per acre. This loss is slightly less than that incurred from natural mortality, and one that did not reduce regeneration levels below the minimum standard.

Ponderosa pine seed trees left from a previous cutting on the Challenge Experimental Forest, California, were removed in October 1963. Logging costs and production rates were compared with those for a seed-tree cutting on an area nearby. Production rates for seed-tree removal greatly exceeded those for the operation as a whole. Skidding production increased by 38 percent or 1,247 bd. ft. per hour. Components of this net increase were: using pre-existing skid roads (+9 percent), a larger average log volume (+59 percent), and cost of safeguarding regeneration (-30 percent). The cost of...

A peculiar, low, shrubby, oak-like plant was discovered by Dale Hall in January, 1962, on the Challenge Experimental Forest (which is maintained by the Pacific Southwest Forest and Range Experiment Station, Berkeley) approximately one mile north of Challenge, Yuba Co., California. It was quite unlike any species known to the senior author and did not appear to be a hybrid of any California oak.

Thermogravimetric Analysis (TGA) is finding increasing utility in investigations of the pyrolysis and combustion behavior of materuals. Although a theoretical treatment of the TGA behavior of an idealized reaction is relatively straight-forward, major complications can be introduced when the reactions are complex, e.g., in the pyrolysis of cellulose, and when experimental imperfections arise. Consequently, a fairly large number of analytical methods have been proposed for obtaining kinetic parameters from TGA curves. Among the proposed methods are several graphical procedures, mostly...

Seeds of brushbox, lemon-gum eucalyptus, and cluster pine were sown in separate seed spots on the Mokuleia Forest Reserve, Oahu. Half the seed spots were mulched. After 1 year, only two brushbox seed spots were stocked; lemon-gum eucalyptus had significantly (5 percent level) more seed spots stocked in the mulched plots; cluster pine had significantly less. These two species show promise for direct seeding on similar sites.

The attraction of turpentine to wood borers under natural conditions was observed by setting up three types of traps in a stand of windthrown timber. The traps were made of hardware cloth, plywood, or pane glass Several species of wood borers and their predators were caught more consistently in downwind traps than in upwind traps. Circumstantial evidence suggests the attraction of turpentine. The wire-mesh traps proved to be the more efficient type of trap.

Past outside bark diameters (d.o.b.) of ponderosa pine in northern California can be estimated from the relation of bark thickness to stem diameter. An equation for estimating past d.o.b.'s has been developed. The relationship appears to be linear between 1 and 20 inches d.o.b. and differs from ratios reported for the species in other areas. Site quality and crown class did not seem to affect the relationship.