Treesearch

Data accumulated for more than 25 years from old-growth sugar pine stands in central California showed that the mountain pine beetle preferred to attack mature and overmature trees with the most decadent crowns. Analyses included four age groups and eight crown types. Beetle outbreaks in second-growth sugar pine were nondiscriminating between trees. These outbreaks developed during drought when heavy populations were reared in snow-breakage debris.

Describes how to make an economical "can-cone"-type storage precipitation gage, based on one originally designed by the California Department of Water Resources. The cone was modified by including an inner skirt to prevent loss of water between the cone and can. Periodic records of precipitation are obtained by stick measurement. Five complete cones cost $120.

A new electronic instrument, called the Heterodyne Vegetation Meter to measure herbage yield and utilization was built and tested. The instrument proved to be reliable and rapid. Further testing will be conducted.

A hybrid pine developed in the course of forest-tree improvement research. by the U. S. Forest Service has caught the interest of Christmas tree growers. It is a hybrid between two races of lodgepole pine (Pinus contorta) produced at the Institute of Forest Genetics at Placerville, California, and has some desirable attributes for use as a Christmas tree: good form and color, relatively rapid growth, and early production of persistent cones.

Hybrids between Abies procera Rehd., and Abies magnifica A. Murr., made reciprocally at Marys Peak near Corvallis, Oreg., and near Placerville, Calif., suggest that no significant genetic barriers prevent crossing of the two species where ranges overlap. Hence, maintenance of species differences must be looked for in other factors. Cotyledon number, a very early expressed trait, was used to verify that recently germinated seedlings were true hybrids. A. magnifica cotyledons averaged nine, A. procera five, and the hybrids at both locations seven, with each seedling population statistically...

A water emulsion spray of DDT applied by hand sprayer to young trees infested with eggs and early-instar larvae of the ponderosa pine tip moth halted further larval activity and effectively prevented all damage.

The principal tree degrade was caused by blue stain fungi introduced by bark beetles and flatheaded borers. Roundheaded borers caused the most serious wood boring. Smaller trees suffered more degrade than larger, and degrade was more severe below 5,000 feet elevation. Degrade due to insects was not as heavy as expected, probably because of cool summer weather and low insect populations before the wind damage.

Theory necessary for sampling with probability proportional to prediction ('three-pee,' or '3P,' sampling) is first developed and then exemplified by numerical comparisons of several estimators. Program 'T RP' for computer generation of appropriate 3P-sample-selection criteria is described, and convenient random integer dispensers are illustrated.

By the year 2000, total lumber consumption in Hawaii is expected to be between 78 and 128 million board feet. Hardwood lumber consumption is expected to exceed 16 million board feet — an increase of nearly 2½ times the present level of use. In contrast, softwood lumber use is expected to remain at about the present level of 79 million board feet. Plywood consumption is expected to be about 40 million square feet (⅜-inch basis). These estimates are based on an expected increase in population in Hawaii between now and the year 2000.

Equations were developed to predict the fuel moisture content of indicator sticks from the controlling weather variables. Moisture content of ⅛-inch thick basswood slats used in the South and East could be determined with about equal precision by equation in the critical low moisture range or by weighing at fire danger stations. The most useful equation developed included three variables: dry bulb temperature, dew point temperature, and dew point depression. The moisture content of ½-inch dowels used in the West could not be estimated by equation as precisely as slats, possibly because...