Treesearch

Immature or unripe seed may be one cause of the poor germination of sugar pine occasionally experienced in nursery practice or direct seeding projects. Ripeness of pine seed, or the time to harvest cones, is usually judged by a change from green to brown in the color of cones or by the development of a firm consistency in the endosperm. However accurately these criteria may be applied, they are subjective and cannot be described well enough to permit consistency in their use. This paper describes an index of ripeness for sugar pine seed.

Propagation of conifers by rooting of cuttings is an old art that has recently benefited by the findings of the plant physiologist. The forest tree breeder may now use rooting as a tool in his efforts to evaluate the heredity of his trees. In a study undertaken to use vegetative propagation of members of a variable hybrid population as a guide for selecting superior individuals, the authors found that wide differences occurred in rooting ability among members of the population, and that in general the differences corresponded in two successive years.

The Eddy Arboretum at Placerville, California, contains more than 90 species, varieties, and hybrids of pines, and is therefore of great interest to horticulturists. The Arboretum was established in 1925 as a source of breeding stock for the Eddy Tree Breeding Station, founded in the same year by Mr. James G. Eddy of Seattle. In 1934 Mr. Eddy presented the Arboretum and Station, now called the Institute of Forest Genetics, to the people of the United States. and the U.S. Forest Service carries on the program of tree breeding.

The temperature profile of a mature forest seldom has been observed. Temperatures at specific locations are of interest to the forester because they may help explain many phenomena, such as growth or death of seedlings and freezing of terminals and floral parts of trees. The opportunity to combine a vertical succession of such temperature measurements into a temperature profile was afforded the author by a battery of thermometers installed in a study of natural regeneration at the Stanislaus Branch of the California Forest and Range Experiment Station. This branch station is located on the...

During the past few years, the Institute of Forest Genetics has received an increasing number of requests for pollen of various species of pine. Many of these requests have been fulfilled; others which stipulated arrival in time for specific crossing operations could not be fulfilled. The accompanying table is compiled to furnish cooperating pine breeders with the dates and places of pollen collection from various pine species and hybrids. This table will be revised and expanded to cover more species and additional genera as circumstances permit.

On the national forests there has been a trend during recent years toward placing on a systematic basis such fire-control practices as rating fire danger, determining the proper size of suppression crews and speed of attack, and planning fire-suppression strategy. This trend has resulted in greatly improving the techniques of planning and managing the fire-control organization. At the same time it has revealed a serious lack of essential information. The outstanding need is for specific data on the rate at which forest fires may be expected to spread under various conditions of forest...

Tables giving average tree volumes by breast-height diameter classes frequently may be used in timber cruising to save money, time, and men. Such tables may be appropriate in cruises of large areas having many trees in low-intensity cruises warranting the sacrifice in accuracy that results from omission of individual tree height measurements, during wartime when men are scarce or when inexperienced cruisers have difficulty in estimating heights. In response to numerous recent requests from cruisers and forest land agencies, nine of the more important tables used by the Forest Service in...

On many thousands of acres of cut-over timber lands in California, brush of various species has gained such control of the soil that the success of natural reproduction is problematical. This condition is particularly serious in the high site quality sugar pine-white fir and sugar pine-ponderosa pine types, where the maintenance of sugar pine in the stands is a silvicultural objective. This study was designed to determine whether clearing the brush from unstocked areas during a good sugar pine seed year would foster natural regeneration of sugar pine and to compare the effectiveness of...

After the chaparral cover of the mountain watersheds in southern California is burned, damage is usually done during winter storms by increased runoff and erosion debris from the denuded area. The damage is done not only to the works of man, but to the watershed itself. Improvements that most often suffer tangible damage include water storage and diversion structures; roads, trails, railroads, and public utility lines; agricultural land; campgrounds , cabins, homes, and even whole communities. Other tangible losses are incurred through the wastage of flood water by-passed to the ocean...

Bitterbrush (Purshia tridentata D. C.) is one of the most important range plants in the West. It is grazed by cattle, sheep, and goats, as well as by deer, antelope, and other game animals, and the seeds are an important item in the diet of rodents and birds. The range of bitterbrush (fig. 1) covers about 340,000,000 acres in the 11 western range States and southern British Columbia. In California bitterbrush is distributed on approximately 7,500,000 acres east of the Sierra Nevada and Cascade Mountains at altitudes ranging from 3, 500 to 11,000 feet. It commonly grows on sites occupied by...