Treesearch

Analyses and interpretations of data from a randomized lightning modification experiment yield strong evidence that AgI seeding of mountain thunderstorms reduces the frequency of lightning and alters several lightning characteristics. Statistical procedures include likelihood ratio tests based on the log-normal distribution and two nonparametric tests (Wilcoxon and sum-of-squared ranks tests). Specifically, the estimated reduction in the long continuing current intervals in cloud-to-ground flashes is about one-fourth (two-sided p-values of both nonparametric tests are less than 0.04)....

Protection from grazing, alternate rest, or seasonal spring or fall grazing did not promote recovery of pine-bunchgrass range in Colorado which had been grazed heavily for more than 23 years. Application of 2,4-D herbicide or NPK fertilizer significantly changed vegetative composition and increased herbage yields of these rangelands under all grazing treatments. The herbicide reduced competition from forbs and permitted the grass species to increase in basal area and produce more herbage than plants on unsprayed, unfertilized control plots. Addition of NPK fertilizer stimulated production...

The primary objective of the research at the Manitou site was to determine at what classification level Skylab photographic products, or their equivalent, can be used for plant community classification in a central Colorado mountainous area. Secondary objectives were (1) to determine the kind of aircraft support photography needed to extend these classifications to other levels in the hierarchy, (2) to determine how both Skylab and aircraft support photography can be used to detect and identify cultural features of a mountainous landscape that could affect resource management alternatives,...

Long distance dissemination of Arceuthobium vaginatum subsp. cryptopodum (Engelm.) Hawksworth and Wiens was studied at the Manitou Experimental Forest, Teller County, Colorado. Specifically, the role that birds play in disseminating the parasite over long distances was examined. Dwarf mistletoe occurrence in an 0.8 km x 4. 3 km area was plotted on 1 :7920 aerial photographs. Thirty two infection centers (satellite centers) were found in 128 h of healthy timber. They were judged to have originated by some means other than or in addition to explosive seed discharge. Satellite centers were...

Dry matter yields of herbaceous native vegetation were effectively estimated with electronic herbage meters. Yields were estimated on vegetation types varying from a low-elevation annual type to a high-elevation alpine type. Phenology, dead organic matter, plant stature, composition, and meter placement within the vegetation affected efficiency of yield estimates. Double sampling techniques are necessary. Optimum sample size for either a fixed-cost or fixed-variance estimate should be determined for each vegetation type.

An expression for describing the effect of aspect and slope on tree growth is illustrated by the relation of western white pine site index to aspect, slope, and habitat type.

The wonders which Phil Briegleb remembered from that stint of work - the dark green spill of forest from ridgeline to valley floor, the colonnade of giant boles crowding acre upon acre, the Depression-staving paycheck earned by sizing up this big timber - may have been grand, all right, but no more so than the language which spelled out the project. The Forest Survey was prescribed in Section 9 of the McSweeney-McNary Act. In that 1928 manifesto which blueprinted the Forest Service's system of regional experiment stations and set the directions of federal forestry research, one sentence...

Volume and characteristics of logging residues from 34 harvest areas are presented. Clearcuts and partial cuts logged to conventional utilization levels and to close utilization levels are included. Residue volumes ranged from almost 3, 600 ft3 /acre of wood 3-inches-plus down to about 550 ft3 /acre, depending on treatment. More than 60 percent of the residues were sound. A high proportion of residues were in pieces under 9 feet in length.

Panels of judges have been evaluating the esthetic dimension of harvested areas in the Northern Rockies. Studies conducted in Wyoming and Montana agree with intuition in that forest scenes are generally liked less as the evidence of man's activities increases.

The Priest River Experiment Station was established in 1911 as the center for forest research in the productive forests of northern Idaho, western Montana, and northeastern Washington. Located out in the forest of northern Idaho, 15 miles from the nearest small town, it was to be the hub of forest research in this large forested area. Within a few years it became apparent that the range of conditions requiring study did not occur on the Priest River Experimental Forest and that the Station was too isolated to serve as the center for research. Thus, Missoula, Montana, headquarters for the...