Treesearch

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...

Acer rubrum L. is a highly polymorphic species occupying a range which includes almost all of the United States east of the prairies, southeastern Canada, and a portion of Newfoundland. The range of habitats occupied is equally impressive. Cytological study of this species was first undertaken by Mottier in 1893, but the first indication of intraspecific polyploidy was furnished by Taylor (Contrib. Bot. Lab. Univ. Penna. 5: 111, 1920), who reported finding in this species three different gametic chromosome numbers which approximated 36, 54, and 72, but was unable to relocate the trees from...

To organize cruises so as to steer a desirable middle course between high accuracy at too much cost and little accuracy at low cost is a problem many foresters have to contend with. It can only be done when the cruiser in charge has a real knowledge of the required standard of accuracy and of the variability existing in the timber stand. The study reported in this paper works out estimates of the average accuracy of cruises in California pine stands and outlines methods whereby the accuracy may be estimated for particular cruises.

The site-class curves presented . . . for the irregular pine-fir forests of California, were first prepared in connection with a yield-predicting procedure . . . developed in 1933. The original curves were designed principally for administrative use of the Forest Service in Region 5. Since they have now come to be accepted by other agencies and for general purposes, this research note has been prepared to make the curves more readily available and to describe their peculiar features sufficiently to enable correct application. It is hoped that this action may contribute to the establishment...

Maps are very useful in providing a picture of the location of vegetation types, but mapping as a method for determining type areas may be inadequate or costly. The measurement of vegetation type areas by means of line surveys is discussed in the following article, and the method is tested in connection with detailed studies on plots. The results indicate that the method has important advantages over mapping.

The period of seasonal growth of trees is not only an interesting natural phenomenon but also may be an important factor in the execution of certain field studies. The data presented indicate some significant differences among the periods of growth of certain coniferous species and in the period of growth of ponderosa pine at different locations.

Since Research Note No. 18, "Collecting and Propagating the Seeds of California Wild Plants," was issued in December 1937, additional information on handling seeds of California species has been accumulated. This information is assembled in the following tabulation, which lists 178 different species, arranged alphabetically by genera. For each species, as in the previous paper, the following information is given in tabular form: Time of seed collection, approximate number of seeds per pound, days elapsed between sowing the seed and germination, highest germination percentage obtained, and...

General principles of forest management were established over 200 years ago in Central Europe and the task of the American forester has been largely to adapt these principles to the management of the vast, rough, and inaccessible natural forests of this country. A series of essentially new problems has arisen, however. In the humid climate where forestry originated, forest fires are relatively rare and unimportant, while in the New World, fire protection is the most serious of all problems facing American foresters. This has necessitated the development of methods of investigation for...