Treesearch

Since no nuclear devices have been detonated by the United States under conditions leading to both mass fires and radiological fallout, a theoretical and small-scale experimental study was undertaken to see if fire-induced convection columns could significantly affect fallout patterns. Experiments were conducted in a 6- by 6-foot low-velocity wind tunnel using full-scale fallout simulants. Values of characteristic parameters of fallout patterns were compared for experiments conducted with and without fire, all other factors being held constant. As predicted by theory, a fire upwind of the...

In 1956 Hallinl reported some observed effects of pruning ponderosa and Jeffrey pine based on the response after 5 years. This report is an extension of those observations, after a 10-year reexamination of the experiment. Hallin suggested that half the live crown, or six-tenths of total height of the tree could be pruned without adverse effects on growth. Pruning out three-fourths of the live crown resulted in death of 52 percent of such treated trees at the end of 5 years. Also of considerable interest was the rapid growth rate found for open-grown trees on the poor site where the study...

The California flatheaded borer (Melanophila californica Van Dyke) kills an estimated 30 million board-feet of pine timber in California each year. The insect is especially troublesome on ponderosa and Jeffrey pines growing on dry sites, and it has caused serious losses in Jeffrey pine stands on valuable , watershed and recreational lands of southern California. An effective control is needed to prevent such losses. This paper presents the results of tests in which the potential of DDT applied as a foliar spray against the adult borers was studied. The tests showed that control with DDT is...

Bitterbrush (Purshia ssp. ) is an important element of range grazing capacity in the West . This browse shrub provides premium forage on many important winter-deer ranges and is a valuable part of the diet of many animals. But the shrubs have been destroyed or damaged over large areas by fire, heavy grazing by livestock and game, insect defoliation, girdling by mice , adverse weather conditions, and possibly other unknown factors. Natural reproduction is not enough in many places to sustain existing stands. Methods must be developed to maintain or improve the stands

A forester faces many problems in selecting the proper seed source of ponderosa pine. He wants a seed source well adapted to all of the conditions of his planting site–one that can tolerate all of the extremes of heat, cold, and drought; that can resist the ravages of insects, diseases, and animals; that can produce the most of the desired product in the shortest time.

White fir (Abies concolor Gord. and Glend.) Lindl.) is an economically important native tree in western United States and parts of Mexico. In the United States it is widely distributed in the Rocky Mountain and Pacific Coast regions, extending from New Mexico and Wyoming, westward to Oregon and California. It attains best development in California and southwestern Oregon.

The estimation of herbage production and· utilization in browse plants has been a problem for many years. Most range technicians have simply estimated the average length of twigs or leaders. then expressed use by deer and livestock as a percentage thereof based on the estimated average length left after grazing. Riordan used this method on mountain mahogany (Cercocarpus montanus Raf.) and service berry (Amelanchier utahensis Koehne) and found that reliable estimates were virtually impossible. Measurements of 10,000 to 20,000 twigs or leaders were necessary with these two species for a...

On June 16, 1957, a trip was made by boat to Little Marin Island, off San Rafael, California, for the purpose of banding in the heronry that covers this small privately-owned island. We also wished to investigate the possibility of Snowy Egrets nesting there. The heron colony was conservatively estimated at 2000 birds, of which approximately 50 per cent were Common Egrets (Casmerodius albus), 20 per cent Snowy Egrets (Leucophoyx thula), and 30 per cent Black-crowned Night Herons (Nycticorax nycticorux) .

Prize-winning essay

Phoradendron, new world counterpart of the European Viscum or Christmas mistletoe, is mainly tropical or subtropical in occurrence. Only the group Boreales, found primarily in southern and western United States and in the highland plateau of northern Mexico, grows in temperate regions (Trelease 1916). In the Atlantic States, one species of this group extends as far north as New Jersey. In the milder Pacific States, several species are found in Oregon, one of them, Phoradendron villosum Nutt, up to approximately latitude 45° N. These limits are much more restricted than those of the host...