Treesearch

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...

As early as 1914 Coert DuBois and his staff recognized that knowledge of the rates which fires spread was essential to sound fire control planning, strategy, and tactics, and therefore designed the fire report form so that such data might be accumulated. Although the individual fire report form has changed appreciably since that time, the supply of data has grown continuously. The need for summarizing this practical fire experience is still present. While more accurate knowledge of the factors influencing fire behavior and their effects is also required, and is being obtained, the informati...

Cutworms, Noctuidae larvae, frequently cause serious damage to natural and planted seedlings in the California pine region. Observations during several years in California and reports from other regions suggest that these insects contribute to frequent failures of plantations and natural reproduction. Careful study of the insects with a view to their control seems justifiable.

A double wash bottle for dispensing two-part fixing solutions is described. Equal volumes of each stock solution are delivered simultaneously into the same vial.