Treesearch

To meet the growing need for a portable instrument capable of accurately indicating water depths in wells and channels over a considerable range, the point gage was designed. As in other electric point gages, the distance of the water surface from a reference point is measured with a plumb-bob suspended on a graduated steel tape. Contact of the bob with the water surface closes an electric circuit, which activates the needle of a milliameter.

The measurement of infiltration has, in recent years, assumed increasing importance as a means of estimating the relative absorptive capacities of soils under different vegetal types or kinds of land use. The utility of infiltration-criteria rests partly on the assumption that surface-runoff in any appreciable volume is deleterious and that it results in movement of soil and in excessive peak-rates of stream-flow. Based on this assumption, a land-use providing maximum infiltration-capacities may be considered optimum for retention and storage of precipitation. In hydrologic investigations,...

The fact that plant cover influences run-off, erosion, and infiltration has been firmly established by past research. Only under a few special conditions, however, has the degree of this influence been determined quantitatively. The study reported in this article was undertaken to secure a usable measure of this quantitative relationship, and to provide data for watershed management in the mountains of Colorado. With the use of small plots, results have been secured which evaluate plant cover as a watershed factor and at the same time demonstrate that under certain circumstances, soil...

The purpose of this bulletin is to bring together the available information on natural regeneration of the western white pine type, based on about 25 years of forest research and 30 years of national-forest timber-cutting experience. Western white pine (Pinus monticola) forms the key species of the valuable western white pine type of northern Idaho and contiguous portions of Washington, Montana, and British Columbia.

Altitude, in broad subdivisions, exerts recognized and well-understood effects on climate. Aspect further modifies the altitudinal influence. Many publications have dealt with the interrelations of these geographic factors with climate and life zones or have discussed variations of individual weather elements as influenced by local altitude and aspect differences and the resultant effects on vegetation types, frost belts, thermal belts, phenology of plants, water resources, and agricultural economics in mountainous countries. Such variations have never before been systematically investigate...

Forest Service administrators and fire-research men have long felt the need of information concerning the effect of vegetation such as shrubs, grasses, and forbs (nongrasslike herbs) on the rate of spread of fires. To date, all knowledge of the subject has been acquired empirically in the field, or deduced from knowledge of fire behavior as influenced by the condition of deadwood, duff, etc. It is known that the luxuriant green vegetation of late spring and early summer does not lend itself to dangerous, fast-spreading fires, and that the matured and naturally cured or dried vegetation of...

The object of the study was to analyze and evaluate the environmental factors which govern the progressional stages of the secondary forest succession in northern Idaho. \When this study began much uncertainty existed regarding the distribution of trees and forest types in relation to temperature, precipitation, and evaporation and regarding their soil moisture and nutrient requirements in this region. Little was definitely known of the conditions which favored good growth and form of trees, or what gave rise to pure as distinguished from mixed stands. Furthermore, more exact and dependable...

The forest industry of the western white pine region depends on the production of white pine as a major species on about 2,670,000 acres of commercial forest land. Continued production of this species and maintenance of the forest industry at anything approaching its present level is impossible unless the white pine blister rust is controlled. Existing merchantable timber can and probably will be harvested before serious losses occur but the young growth, which is the commercial future of this industry, is the great value at stake. The stakes are large - a major industry of the Inland...

A satisfactory silvicultural management of ponderosa pine stands requires a judicious selection of trees to be left in the reserve stand. The timber marker must know what type of tree has the greatest growth potentialities and what type of tree will respond but slightly upon being released. The silvicultural problem in marking therefore is one of recognizing the combination of characters, age, and crown vigor, which indicate high or low growth capacities. The trees selected for cutting should be those which have ceased growing or which have lost their ability to respond to an increase in...

On August 27, 1937, Lloyd G. Hornby died of heart failure on the Toboggan Creek forest fire in the Clearwater National Forest. Few if any men in or out of the U.S. Forest Service have made a greater contribution to fire control planning than did he. In the following article, H. T. Gisborne outlines the principles of fire control planning developed by Mr. Hornby, emphasizing the major features which have too often been obscured by the detailed technical procedures of the component processes of fuel type classifications, seen area mapping, smokechaser coverage, transportation planning, etc.