Treesearch

This review article presents a summary of the knowledge of pyrolysis of cellulose and the factors that affect it.

The second year's data of a study designed to test the effects of perennial grass competition on the vigor of bitterbrush (Purshia tridentata) in an area of heavy bitterbrush mortality are reported. The data demonstrated that competition from other plants, mainly perennial grass, significantly reduced bitterbrush growth.

Systematized codes for plant names are helpful to a wide variety of workers who must record the identity of plants in the field. We have developed such codes for a majority of the vascular plants encountered on California wildlands and have published the codes in pocket size, using photo-reductions of the output from data processing machines. A limited number of the pocket-guides is available for distribution to field workers from the Director, Pacific Southwest Forest and Range Experiment Station, P.O. Box 245, Berkeley 1, California.

Routine business records of towlift tickets or restaurant receipts provided estimates of total attendance over a 2-month period within 8 percent of true attendance, and attendance on an average day within 18 to 24 percent of true attendance. The chances were that estimates would fall within these limits 2 out of 3 times. Guides for field use can be worked out after further tests and model development.

Volatility and vapor saturation were obtained for closed-faced collected resin of 10 pine species and 4 hybrids in California. Volatility ranged from 2 to 32 percent at 25°C., and from 14 to 36 percent at 100°C. Hybrids were usually less volatile than either parent. Vapor saturation ranged widely between species, from 2 to 20 mg. per 150 cc., but only slightly within a species; hybrids were usually intermediate between the two parents.

As a land use, an activity, and an industry, forest recreation is rapidly growing in importance. But it is relatively new in terms of objective data and theory. Critical problems are being met by an interdisciplinary research team drawing on seven fields of knowledge. Research problems, approaches, studies, and plans are summarized.

Use of radioactive probes inserted in mountain snowpacks may make possible more accurate appraisal and prediction of snowmelt water. Commercially available gamma and neutron probes were tested for their ability to measure snow density, ice lenses, and the thermal quality of individual layers in the snowpack.

Fuel temperature is and has always been difficult to measure. To understand better the problem of fire and fire weather behavior, it is important to measure this variable. We have developed for field use a new fuel temperature counter which can be used to obtain such measurements quickly and easily. This electronic recording instrument is easy to construct and operate, is highly portable, has low power requirements, and will operate up to 2 weeks without attendance. It consists of three fuel temperature sensors, a pulse generator, a timer, and an accumulating counter (figs. l and 2).

Ponderosa pine planting stock (1-0 and 2-0) grown from five different seed collection zones in the California pine region differed noticeably in size. On the west side of the Sierra Nevada, seeds from zones above 4,000 feet yielded smaller seedlings than those from lower zones, but larger seedlings than those from east-side sources. Average dimensions (seedling weight , stem diameter, top height) reflected these interzonal differences at each of five nurseries throughout the State.

Heavy use of 137 National Forest campgrounds and picnic areas surveyed in California has resulted in several critical types of site deterioration. More than half were inadequately stocked; four-fifths were disturbed 1963 by trampling , erosion, and mechanical means; and two-thirds had poor accumulations of protective plant litter on soil surfaces. Ecological studies of recreation site capacity, site maintenance and site improvement are required to supplement currently improved practices of campground and picnic site management and to develop new ones.