Treesearch

Comparisons are made between Ignition energies of forest fuels, including newspaper, determined during Operations BUSTER, SNAPPER and UPSHOT-KNOTHOLE and laboratory exposures made utilizing the Forest Service thermal source. Agreement is excellent for fuels exposed normal to the radiant flux when fuel moisture content is considered. Ignition of fuels exposed at attitudes other than normal to the radiant flux is not discussed. Ignition energy-moisture content relationships which include the effect of weapon yield are presented. Although presented relationships lack complete scientific...

Daily weather elements of precipitation, wind, mean temperature, relative humidity, and dew-point temperature for selected urban areas (approximately 850,000 population) in the United States are statistically analyzed to determine their correlation with daily number of building fires. The frequency of urban building fires is found to be significantly correlated with relative humidity in summer and dewpoint temperature in winter. No significant correlations are found between urban fires and weather elements such as wind, rain, and snow. Prediction curves relating number of building fires to...

To provide a better basis for silvicultural practices in the pine region of California, we are reporting the results of 28 years of study of seed crops. The study covered the development of cones, periodicity of cone crops, types of trees bearing cones, climatic and biotic factors affecting cone crops, and the dispersal of seed. The findings reported here should help foresters do a better job of planning silvicultural practices.

Creating ground conditions favorable to regeneration immediately after the final harvest cutting is basic to forest management wherever advance growth is deficient. Ponderosa (Pinus ponderosa Laws) and Jeffrey pine (Pinus jeffreyi Grev. & Balf.) seeds require bare mineral soil for satisfactory germination. Pine seedlings, whether from natural seedfall or planting, survive and grow vigorously only when free from competition with other vegetation. This article describes methods used and reports the cost of site preparation in recent years at the Blacks Mountain Experimental Forest in...

Many winter deer ranges throughout the West have been steadily deteriorating as a result of overgrazing, fire, and insect depredations. Lack of winter forage has caused heavy mortality of deer. The problem has become so acute that some of the western states have started research to determine what can be done to rehabilitate these ranges, if and when the causes of deterioration can be controlled.

Residual tanoak (Lithocarpus densiflorus (Hook. & Arn.) Rehd.) trees and tanoak sprouts often are an important component of the vegetation which competes with conifer reproduction in northwestern California. Sometimes enough tanoak is present in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands to dominate the ground completely after logging. And tanoak sprouts develop vigorously after parent trees are destroyed by fire or logging (fig. 1), thereby providing severe competition to conifer reproduction. Although tanoaks generally are considered undesirable at present, someday they...

The composition and characteristics of the needle oils of western pines may provide criteria for distinguishing pine hybrids and may help explain why some needle-feeding insects select certain pine species as hosts.

Available data on the behavior of wood undergoing charring and weight loss are summarized.

Brush competition is one of the more serious obstacles to survival of both planted and naturally established trees in California. Brush has taken over many cutover and burned areas. In the western Sierra Nevada alone, 1.7 million acres of commercial forest land are classified as poorly stocked or non-stocked. All of this area is capable of producing forest trees, but brush dominates most of the ground and greatly hinders efforts by man and nature to reestablish conifers in adequate numbers. If these acres are to produce timber within a reasonable period, the brush must be either eradicated...