Treesearch

Incense-cedar (Libocedrus decurrens Torr.) is one of the most distinctive trees in the mixed conifer stands of western United States. Its range extends from the southern slope of Mt. Hood in Oregon southward in the mountains to Lower California. It occurs in the Cascade Ranges and Siskiyou Mountains in Oregon, the Coast Ranges and the Sierra Nevada in California, where it extends into western Nevada near Lake Tahoe, and in the Hanson Laguna Range and Sierra de San Pedro Martir in Lower California. The total net volume of live incense-cedar sawtimber on commercial forest land in the United...

The most noteworthy feature of Jeffrey pine (Pinus jeffreyi Grev. & Balf. ) is its similarity in appearance and behavior to ponderosa pine (Pinus ponderosa Laws.), a much more widespread and better known species. At one time Jeffrey pine was considered to be a variety of ponderosa pine, and lumber markets make no distinction between the two species because their wood differs little in structure and properties. Because of the apparent similarity of silvical characteristics and wood, usually no distinction has been made between the two species in either management or research records.

Research at the Institute of Forest Genetics at Plaeerville, California since its inception in 1925, has been concerned with the variation in individual trees of a speices. We are interested in this variation as a guide to selection of outstanding individuals. Western forests have considerable diversity in soils, topography, species composition, and distribution of age classes in stands. All of this variability is reflected in the phenotype of the tree and tends to make field selection of genetically superior individuals difficult. Is an outstanding tree genetically superior, or is it just...

Today I would like to tell you briefly about the efforts of forest geneticists to improve the quality of forest trees. What do we mean by quality? Here, the consumer has the first word. The trees we produce are primarily for timber production, and the timber growing and wood-using industries give us our guidelines. Nevertheless, many of the characteristics sought by these industries are of interest to geneticists working primarily with shade-trees. For example, tolerance of freezing, resistance to drought and disease, growth rate, stem form, crown shape, color, and flower characters — all...

Since 1937, methods developed by the author have been used successfully to isolate, identify, and germinate seeds of Ribes spp. from samples of duff and soil collected in sugar pine forests. As here described, similar methods were used to show variation in kind and quantity of seeds of many species occurring in soil and duff samples taken from the Stanislaus Experimental Forest, near Pinecrest, Tuolumne County, California. Timber species found on the sampled areas were sugar pine (Pinus lambertiana Douglas), pondersoa pine (Pinus ponderosa Lawson), Jeffrey pine (Pinus jeffreyi Grey. &...

The preponderance of white fir regeneration on sugar pine management units has always plagued forest managers in the sugar pine-fir type in the Sierra Nevada. Clear cutting small even-aged groups appears to offer at least a partial solution to this problem. In one recent study more white fir than sugar pine seedlings in openings died within 2 years, and more white firs were damaged by freezing and browsing. As a result sugar pine has a head start in the race for dominance.

Fertilizing seed trees may be one way to improve reforestation of cut-over and fire-destroyed timber stands in California. One of the chief difficulties in reforestation here is that most of the commercial conifers do not produce good crops of seed-bearing cones often enough. Heavy crops have been as much as 7 years apart. As a result an adequate supply of seed for natural regeneration seldom occurs at the right time on cut-over areas. If artificial regeneration is relied on for new timber crops, tree planters have to collect and store large quantities of seed during the few good years to...

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.