Treesearch

These guidelines were initially prepared as part of the FUEL-BREAK Program by Jay R. Bentley, Craig C. Chandler, and Verdie E. White, of the Pacific Southwest Forest and Range Experiment Station, from suggestions by field personnel. The guidelines were reviewed and revised by a committee as follows: Robert H. Blanford, Elmer Chambers, and Len Chatten of the California Division of Forestry; Harvey T. Anderson and R. M. Van Wagner of the Los Angeles County Fire Department; and Lynn R. Biddison and Lloyd R. Britton of the U.S. Forest Service. These guidelines will be subject to revision in 1963.

An average sawtimber stand having a dense understory was converted to one type of fuel-break for $132.00 an acre. Qualified observers believe this barrier would either stop or help in controlling a rolling fire under severe burning conditions.

Have you ever tried to use paint that had too much thinner? If you have, you know that it drips and runs. But paint that is “just right” stays in place. This property of a liquid that causes it to adhere to a solid surface--viscosity--is also valuable for materials used in coating the surface of fuels to retard and suppress wildfires. Viscous water and algin gel are two new materials designed to “stay put” on fuels. They have been tested extensively to determine their characteristics and their effectiveness on different types of fuels. They are only two of many chemicals being investigated...

Three white pine hybrids exposed to infection by white pine blister rust (Cronartium ribicola Fischer) since 1946 have inherited the relative resistance of their parental species. The hybrids were produced from controlled pollinations in 1940 and 1941 at the Institute of Forest Genetics, Placerville, Calif. Twelve seedlings of each hybrid were planted in 1946 on a site near Rhododendron. Ore., where rust infection and growing conditions were severe. Concurrent tests at this locality showed the relative resistance of the parental species: Pinus monticola Dougl., very susceptible; P. strobus...

Tree growth, like all plant characters, is a product of the interaction of genes and environment; however, the genes, environment, and interaction are not the same for every individual of a species. Genes exert master control over the plant's growth mechanisms. They control mechanisms for responding to environment and for utilizing environment in growth. Usually many genes control growth, and their individual effects are thought to be additive. The contributions of the individual genes establish the genetically fixed range of tolerance of a tree. The environment supplies the raw material...

Board foot volumes have been determined for ponderosa pine, sugar pine, white fir, and Douglas-fir in 90-year-old mixed-conifer stands on the Challenge Experimental Forest, near Oroville, California. Productivity is high—site index 140 feet at 100 years. Following the technique described by Boe, the scaled volumes of felled trees were plotted on logarithmic graph paper against the volumes for the same species in the Region 5 Volume Tables.

In a dense forest that has been thinned recently there are often some tree stumps that are still alive and growing despite the loss of their green tops. Such stumps have been noted for many years and are known to be products of root-grafting between trees (Bormann and Graham 1957). If light cutting or windfall occurs in a dense stand where root-grafting is common, food materials in the standing members of a grafted clump will move through root-grafts into the fresh stumps. Thus the cambium of a stump can continue to add increments of wood and bark. This paper reports on studies of the...

Old-growth timber is still the main source of ponderosa pine sawlogs in California, but the proportion of the annual cut from young-growth sawtimber is expected to rise rapidly in the future. The increasing significance of the young-growth resource is particularly apparent in the westside Sierra subregion, where the Challenge Experimental Forest is located. In this subregion, almost 20 percent of the annual softwood sawtimber growth on commercial forest land is in young-growth sawtimber.

Fuel-breaks in southern California are wide strips cleared of heavy brush to break extensive brushfields into manageable units. The breaks also provide open areas from which men can safely and effectively fight fires. Permanent revegetation of these cleared areas with a cover of light fuel is necessary to protect the soil. Perennial grasses are best for this purpose where they are adopted, but annuals such as ryegrass have a place on some areas. Commercial annual ryegrass (Lolium multiflorum), often seeded in the past on burned areas to provide temporary cover while brush is growing, does...