Treesearch

Posts of ohia and robusta, pressure- treated with two preservatives--chromated copper arsenate and pentachlorophenol, are being tested for durability at the Makiki Exposure Site, Honolulu, Hawaii. All treated posts are still sound after 5 years. Untreated ohia posts averaged 4 years of service life before failing; untreated robusta posts averaged 4 ½ years.

Fresh and chemically fixed sectioned plant material can be quickly stained by applying a Brook Cyte Chrome I polychrome stain. Staining time averaged only about 10 minutes. And exact timing of staining and de-staining is not as critical as with most of the commonly used stains. The overall quality is comparable to that of the traditional stains.

The use of large-scale 70 mm. aerial photography proved to be an effective technique for detecting trees in white fir stands killed by Douglas-fir tussock moth in northeastern California. Correlations between ground and photo estimates of dead trees were high. But correlations between such estimates of lesser degrees of tree damage--thin tops and topkill--were much lower; increased training of interpreters could improve these correlations.

The lookout tower offers a ready-made platform from which the speed of true unobstructed wind can be measured, then reduced to equivalent of 20-foot wind. Tower-mounted instruments must meet the requirements of a lightning conductor system, but should also be easily installed and removed for storage and maintenance. Lightweight aluminum mountings for catwalk or flat-roofed installations are described.

Six imported and eight Hawaii-grown species are being tested for their natural resistance to decay and insect attack. Damage to the heartwood has progressed far enough in 4 years to allow comparisons among some of the species.

A survey of the primary forest products harvested in Hawaii in 1967 showed a total value of $334,000, a 24 percent increase over the value in the 1958 survey. Compared with the earlier survey, the volume of sawlogs and treefern harvested has gone up while the volume of fuelwood and posts harvested has declined.

The terrain visible from a given point can be determined quick and efficiently by a computer. A FORTRAN subprogram--called VIEWIT--has been developed for this purpose. Input consists of data on elevations, by coordinates, which can be obtained from maps or ae rial photos. The computer will produce an overlay that shows the maximum area visible from an observation point. Both the observation point and the length of line-of-sight are variable. This new technique makes it unnecessary to draw overlays manually.

Heat-resistant anemometers have been developed for measuring horizontal and vertical air flow in fire behavior studies. The anemometers will continue to produce data as long as the anemometer body is less than 650°F. They can survive brief immersion in flame without major damage. These air-flow sensors have aluminum bodies and rotor hubs and stainless steel cups or vanes supported by stainless steel tubing. The anemometers are suitable for use in normal situations as well as in high temperatures.

A portable station for recording fire weather data has been developed for use in wildland fires, prescribed burns, evaluating sites for fire weather stations, and fire research. Housed in a mechanic's tool box, the station weighs about 60 pounds. One man can have it ready to operate in about 15 minutes. The unit can record five weather variables, but additional data can be recorded by modifying the electronic circuitry. Data are recorded on strip chart recorders.

Two fires burned in the same area in southern California under nearly similar weather conditions, 11 years apart. Yet the Inaja fire of 1956 was much more disastrous than the Pine Hills fire of 1967. The earlier fire claimed 11 lives, and covered an area five times larger than the 1967 fire. Differences in fuels, topography, fire behavior, fire-control action, and severity and duration of Santa Ana conditions help explain the differences in the size of the two fires.