Treesearch

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...

The University of California's Wildland Resources Center has established a new program of forest gene conservation to ensure that California's rich and diverse forests maintain their vigor and productivity in the face of human activities. At an international level, conservation biologists recognize the importance not only of protecting rare species from extinction by safeguarding habitats, but of caring for the genetic diversity of established forests. In some parts of the world past neglect, insufficient knowledge of genetics, and indiscriminate forestry practices have resulted in forests...

The locations and characteristics of five, small, previously undescribed stands of bishop pine (Pinus muricata) in central Marin Co., California, are reported. Three stands lie on dry sites in the Kent Lake Drainage north of Mt. Tamalpais: San Geronimo Ridge, a spur ridge above Little Carson Cr., and Oat Hill. These stands are anomalous in occurring 15 km from the ocean and up to 435 m in elevation. The remaining two stands are on rocky, dry sites on the west slope of Bolinas Ridge, near the McCurdy Trail, and south of Wilkins Gulch. Trees of all stands have slower growth, more spindly...

Of the seven pines that compose subsection Oocarpae (Little and Critchfield) in the genus Pinus, only the three Californian species form a coherent group, while the other four differ from each other and from the Californian species. Traits of the Californian species (Pinus radiata, P. muricata, P. attenuata) vary in complex geographic patterns, a situation that has led to nomenclatural confusion. Modern studies of genetic variation clarified some relationships among the taxa and uncovered other new problems. The taxonomic history and present status are reviewed and discussed. Monterey pine...