Treesearch

Fire weather stations used to be located only where observers were available. Now, remote automatic weather stations can sample weather without manual assistance, virtually anywhere, Locating them, however, remains a problem. An objective method was developed for designing a fire weather network. The design process begins with the identification of the area to be sampled, the relevant meteorological variables, target meteorological fields, and interpolation (or other analysis) method to be used. Using a least-squares criterion, optimum networks for a varying number of stations are computed...

The usefulness of an analytical model as a fire management decision tool is determined by the correspondence of its descriptive capability to the specific decision context. Fire managers must determine the usefulness of fire models as a decision tool when applied to varied situations. Because the wildland fire phenomenon is complex, analytical fire spread models will have descriptive limitations. Some limitations in the widely used and accepted Rothermel fire spread model are discussed in terms of the model's assumptions and mathematical formulations, in the context of prescribed burning...

The historic Bel Air fire of 1961 was not unusually large or fast-moving, nor was it a disaster for the native chaparral ecosystem. Yet it was disastrous for residents of the area, a consequence of unrestricted urban development in the chaparral of Southern California. Its costs included human suffering and financial loss from the destruction of 484 of 2,300 homes.

The summer of 1933 in northwest Oregon had been exceptionally hot and dry. When in mid-August, hot, dry winds blew in from the east, all the fire crews were ready. But there were not enough of them. Scattered fires that started in the coast range merged into what became known as the Tillamook Bum. In 1986, the Forest Service is researching procedures to forecast severe fire-weather conditions like those of 1933 far enough in advance to move fire crews and equipment from where little fire activity is expected to areas where conditions point to high fire danger and a shortage of equipment...

Check the laboratory reports after your next physical. You'll find information on a number of biochemical processes. Procedures like those used in the medical sciences are yielding valuable information about genetic differences among trees and tree pests. New procedures that provide ways to isolate and move genes are advancing progress in tree improvement. These procedures can be applied to forestry because life processes are remarkably similar in all organisms.

Unlike most white pines, sugar pine (Pinus lambertiana) is severely restricted in its ability to hybridize with other species. It has not been successfully crossed with any other North American white pine, nor with those Eurasian white pines it most closely resembles. Crosses with the dissimilar P. koraiensis and P. armandii, both native to eastern Asia, have produced one and a few hybrids respectively. These Asian species are highly resistant to white pine blister rust (Cronartium ribicola), and hybrids and hybrid derivatives of sugar pine X P. armandii show some enhancement of resistance...

Monoterpene and isozyme loci, used as markers to study the genetic structure of Scots pine (Pinus sylvestris L.) native to Scotland, showed that the endemic populations are not genetically impoverished, in spite of severe contraction in range and numbers as a result of both natural and anthropogenic causes. On the contrary, variability in the relict populations is almost the highest of any plant species studied, with average heterozygosities of 0'33 for monoterpenes (five loci) and 0-30 for isozymes (16 loci). The overwhelming proportion of this variability (> 95 %) was within populations,...

Many North American and Eurasian white pines retain their ability to hybridize even after long isolation, and about half of all white pine hybrids from controlled pollinations are inter-hemisphere crosses. Within the morphologically homogeneous and otherwise highly crossable core group of white pines, an exception in crossing behavior is Pinus lambertiana of western North America. Although it is an archetypal white pine in its winged seeds and long, unarmed cones that open at maturity, P. lambertiana has not been successfully crossed with any other species in the core group. It has been...

Building Acacia koa, Hawaii's most marketable native tree, into a viable resource is economically and eco1ogically desirable. But little is known about natural stand development and management of this scarce resource. Therefore, the effect of thinning, fertilizing, or both on short-term growth and survival was studied in a stagnated 12-year-old koa stand on Kaleakala, Maui. Mean relative basal area growth rates (RGR) for the period 1975-77 ranged from 6.7 percent per year for control trees to 10.0 percent per year for thinned-fertilized trees. Both thinned and thinned-fertilized trees grew...

Blowdown in shelterwood, sanitation cuts, and other partial cuts on the Kings River Ranger District, Sierra National Forest, are due to Mono winds. Both winter storm and Mono winds were considered as causes of winter blowdown. All evidence, e.g., direction of tree-fall and occurrence of high wind events, point to Mono wind events as the cause of blowdown. Only 12 percent of Mono wind events cause blowdown. Windspeed during a Mono wind (northeast winds) blowdown averages 50 mi/h with gusts to 100 mi/h. The probability of a blowdown occurring is about once per year, with some years having...