Treesearch

For at least 20 years foresters have been experimenting with methods designed to reduce transpiration from planted conifers. The object is to decrease the water requirement of the plants until the root systems become adjusted to their new environments and are able to supply enough water for the trees to survive. Despite the fact that relatively few clearcut instances of success have been published, considerable enthusiasm for use of transpiration retardants exists.

The purposes of this bibliography are to enumerate and describe publications that have a bearing on the growing of sugar pine for timber production. It is intended primarily for the information of forest managers, and it includes mainly those articles which appeared to pertain rather directly to management. Although a careful search was made for titles, no claim is made that all possible informative sources of information have been included.

Ecological studies of the genus Ribes have been in progress in northern California for more than 20 years. A thorough under- standing of the ecology of native ribes in general, and of the Sierra Nevada gooseberry (Ribes roezli Regel) in particular, is necessary in connection with the control of the white pine blister rust in California. This disease of five-needled pines, caused by the fungus Cronartium ribicola Fischer growing on ribes as its alternate host, threatens to destroy sugar pine (Pinus lamberliana Dougi.) on about a million and a half acres of forest land that supports sufficien...

The transfer theory is applied to the problem of atmospheric diffusion of momentum and heat induced by line and point sources of heat on the surface of the earth. In order that the validity of the approximations of the boundary layer theory be realized, the thickness of the layer in which the temperatures and velocities differ appreciably from the values at infinity must be small compared to the height of the region of influence. Variations of four dependent variables--inflow rate, inflow velocities, maximum velocities, and maximum temperature--as a function of elevation for representative...

Thirty years of research in the ponderosa pine and mixed conifer forests of the Sierra of California by Dunning and his associates have shown that previous methods of silviculture were not providing adequate restocking of pine. Analysis of records indicated a new approach was necessary. From this work, new procedures that gave most promise of success were formulated by Duncan Dunning. These procedures are techniques for applying unit area control in the ponderosa pine and mixed conifer forests.

When the forester finds planting necessary to regenerate an area he should know which species and class of planting stock is best suited to his particular operation. He should also weigh the expected successes on various locations which could be planted. Through such a procedure the best planting locations will be given priority and the best results, measured by survival and growth, will be obtained from the efforts expended. A test conducted at the Blacks Mountain Experimental Forest, an area typical of the California eastside pine type, has shown that survival of ponderosa pine (Pinus...

Squirrels may harvest a far greater proportion of ponderosa pine cones than many foresters realize. This was evident while making a routine cone count on a number of permanent plots on the Stanislaus Experimental Forest near Pinecrest, California, in September 1952. Ponderosa and Jeffrey pines were the predominant species affected. Many ponderosa pines had more than half their total number of cones cut and destroyed.

Sodium fluoroacetate (compound "1080") and, to a lesser extent, red lead and zinc phosphide, have been suggested for use as rodent repellents in direct seeding. On the basis of a small test in 1950 on the Stanislaus Experimental Forest in California, none of these chemicals appears effective as repellents even though all three are effective as poisons.

A new type of protective screen for seed spots has attracted the attention of foresters on the Pacific coast. This screen is cylindrical in form, 4 inches long, about 1 inch in diameter, and is formed from 8-mesh hardware cloth. Foresters have named this protective device a "K-screen". K-screens appeal to the forester because they are relatively cheap, can be pre-loaded with seed and germinating medium before being transported to the field, can be placed quickly, and may not need to be removed from the seed spot. To protect the seed from rodents, the tops of the screens are pinched...

Activity in pine breeding has increased throughout the temperate forest regions of the world since the Institute of Forest Genetics issued its first summary of pollen collection dates in 1947. Cooperation between pine breeders has increased at the same time. The information most essential for conducting cooperative breeding operations are the dates of pollen collection (which also approximate the dates at which the bagging of flower buds to control pollination should be done) for various species at various localities. This publication, adding four years' data to the note issued in 1947,...