Treesearch

Mathematical models can be used to solve quickly some simple day-to-day marketing problems. This note explains how a sawmill production manager, who has an essentially fixed-capacity mill, can solve several optimization problems by using pencil and paper, a forecast of market prices, and a simple algorithm. One such problem is to maximize profits in an operating period where total costs are insensitive to the rearrangement of production schedules.

Seeds collected from 17 Pinus sabiniana Dougl. populations in California were tested for germination. Unstratified seeds germinated slower than stratified seeds. Germination of stratified seeds showed distinct population differences. Some populations started germination at 5°C. and reached a level of 60 to 70 percent after 30 days at 25°. Less than 10 percent of the seeds germinated in 30 days at 25°C. in the slowest samples. Replication with seeds from "slow" and "fast" germinating populations showed that the type of response was similar for different samples within a local area, and from...

Thirteen insecticides were tested against Ips paraconfusus Lanier, and six against the western pine beetle (Dendroctonus brevicomis Lec.). The ranking of toxicity at LD90 by topical application to I. paraconfusus was: SD 3450 > endosulfan > malathion > lindane > phorate > carbayl > carbophenothion = Imidan > crotoxyphos > dimethoate > DDT > Dilan > trichlorfon. The ranking of toxicity to D. brevicomis was: Zectran = dichlorvos > Dursban > malathion > pyrethins = Endane. Five compounds-Zectran, Dursban, malathion, dichlomos, pyrethrins-show promise for study as possible alternatives to...

Trials are underway to detemine the feasibility of direct seeding timber species to specific sites. Three major timber species were direct seeded on a moist, cindery, low-elevation site on the island of Hawaii. After 1 year, West Indies mahogany and monkey-god had acceptable stocking; stocking of lemon-gum eucalyptus was considered poor. All thee species made rapid height growth. If more extensive trials result in similar stocking for West Indies mahogany and monkey-pod, direct seeding can be considered a feasible method for establishing forests of these two species.

Studies in northeastern California showed that the number of dwarf mistletoe (Arceuthobium campylopodum) seeds trapped declined at a logaithmic rate as the distance from overstory source of infection increased. The most seeds were dispersed in the direction of preuading winds. It Is quite likely that storms also aid dispersal. Total numbers of seeds trapped varied from year to year, sugesting good as well as poor years of seed production. A distance of 100 to 150 feet from infected overstopy trees is necessary to prevent infection in regeneration.

Survival, growth, and tree quality of 84 introduced species planted from 1956 to 1960 on the Waiakea Arboretum, near Hilo, Hawaii, were measured in 1970. Four species show good-to-excellent growth and good potential for timber use: Queensland maple, black cypress-pine, rosegum eucalyptus, and Amammanit eucalyptus. Several other species have good reforestation potential, but less desirable wood qualities. Rate of survival was lowest among the pines.

A new computerized technique called VIEWIT for measuring the terrain visible from a given point was applied in a study on the Black Hills National Forest, South Dakota. The seen area from 12 heavily visited scenic points and along three proposed routes for a scenic tramway were delineated. The computer produced overlay maps that show the maximum area visible from each obsewation point.

Genetic, environmental, and age effects were found in 29-yr-old ponderosa pine progenies from different elevational sources, when they were grown at 960, 2730, and 5650 ft elevation in the Sierra Nevada of California. Wood specific gravity decreased as elevation of seed parents increased, and all genotypes produced significantly lower specific gravity wood in the high-elevation plantation. For ponderosa pine under similar conditions, if higher specific gravity wood is wanted, low-elevation seed sources should be used, or plantings made at low elevations, or both. If lower specific gravity...

Five enzyme classes from 11 developmental stages of germinating embryos were separated by starch gel electrophoresis. Alcohol dehydrogenase isozymes found in embryos of dry seed were most active at the time of radicle emergence; activity decreased thereafter, fading below the level of detection when seed coats were shed. Peroxidase isozymes were absent and esterase isozymes were nearly absent from stratified seed, but both increased steadily in number and stainability from time of radicle emergence through epicotyl elongation. Leucine aminopeptidase and catalase isozymes were detectable in...

In Acer and many other woody genera, leaf form changes drastically and often abruptly during the life of the plant. Heterophylly is of two principal kinds in these woody plants: (1) changes during seedling and post-seedling stages, and (2) changes during the development of single annual shoots of adult plants. Type (1) is ubiquitous in Acer] type (2) is a regular feature of some species but uncommon or poorly expressed in others. These two types of heterophylly tend to converge; deviations in leaf shape on adult plants are often in the direction of seedling leaves. This tendency of woody...