Treesearch

Critical appraisal of dwarf mistletoe damage and of rate of spread and intensification may depend on knowledge of mistletoe population characteristics. Studies of dwarf mistletoe (Arceuthobium campylopodum) on red fir (Abies magnifica) were made by cutting and examining 14 trees 24-86 years old (avg 58). Bole infections, tallied separately, were found on all but 1 tree and averaged 2.2/tree. Of the 1,299 branch infections examined, 23% were dead. Of the remaining live infections, 51% bore shoots, 18% bore fruit, and only 5% bore large fruiting clumps. These observations indicate that only...

Stands of red fir and white fir in California are extensively infected with the fir dwarfmistletoe, and damage is heavy over much of the fir belt. Field observations and cross-inoculation studies show that there are two specialized forms of fir dwarfmistletoe, one attacking only red fir and one only white fir. In most fir stands, only one form is present in a given area. In such stands, reduction of mistletoe damage through stand conversion or through selective thinning of reproduction is suggested. Where both forms of mistletoe are present in the same stand, standard control procedures or...

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. They were reviewed again in February, 1963 by J.R....

A fuel-break is a wide strip or block of land on which native brush fuels have been reduced or eliminated to facilitate fire control. Brush removal creates a plant vacuum which should be filled rapidly with plants that will protect the soil against erosion, produce lower fuel volume than native chaparral, and possibly provide grazing for wild or domesticated animals. Fuel-breaks are usually constructed along ridge tops, but also along mountain roads, and valley or canyon bottoms. Topography may be steep and irregular, soils shallow and course; rocks, brush, and stumps may cover much of the...

Without effective, economic techniques to control regrowth of brush, permanent modification of large areas of chaparral to a stable cover of low fuel volume is virtually impossible. The aggressive reestablishment of most brush species after top removal will soon cancel out any value of an initial clearing operation. In 2 years, regrowth may attain a height of several feet. Grass or other cover being established for soil protection is rapidly crowded out. Practically all of the brush plants--except those left for esthetic purposes--must be eliminated. If they are not, reclearing is necessary...

"How much will it cost?" This question is asked in the planning stage of every brush conversion. "To bulldoze? To spray? To seed?" Frequently there is no experienced person standing by to answer. To provide-such information, we have assembled notes and figures from fuel-break studies at the San Dimas Experimental Forest, and from brush conversion projects by the California Division of Forestry, the National Forests in southern California, and the Los Angeles County Fire Department.

Late model helicopters equipped with new helitanks and adequately supplied can accurately deliver as much fire retardant as most fixed-wing air tankers at a potentially lower cost. Viscous water dropped from helicopters clung to fuel surfaces and was concentrated in a narrower pattern than plain water.

Operational tests conducted from air tanker bases in California in 1962 confirmed earlier laboratory and field studies and showed that viscous solutions of diammonium phosphate (DAP) are more effective than any other presently known fire retardant. These tests also indicated that corrosion is not a serious problem if inhibitors are used and equipment is properly maintained. Some storage problems still remain.

Soil pore volume and pore size were correlated with land use or vegetation cover type. The top foot of forest soils had more large pores and higher water-holding capacities than that of soils under cultivation, in pasture land, or in idle grassland.

In the first year of studies of moisture in living fuels, pine and manzanita had dissimilar moisture trends, the moisture content of brush varied with elevation during the growing season, and soil moisture was correlated with brush foliage moisture.