Treesearch

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...

In an exploratory study of personality and background, children who, according to California Division of Forestry files, had set two or more fires were compared with children who had set only one fire. Multiple-fire setters were characterized by several associated problems, such as excessive activity, aggression, and psychosomatic difficulties as well as family and school difficulties, rather than by a single distinguishing attribute. First offense firesetters who show any evidence of these associated problems should be considered potential fire-problem children. Their early identification...

Potential redwood crop seedlings, 3 to 4 years old, were released from competition with shrubs and herbs in a trial on the Redwood Experimental Forest, North Coast California. The release distances tested were radii of 2, 3, and 4 feet; the methods used were basal spraying and foliage spraying with 2,4,5-T and 2,4-D mix, and hoeing-cutting. For the first 3 years, released seedlings grew faster than untreated seedlings. By the end of the fourth growing season, when competing vegetation had already reoccupied the weeded areas, height growth of all seedlings appeared to be equalizing. This...

Douglas-fir seedlings were planted by four methods in late February and late March on hot, south-facing slopes in northwestern California. Besides standard planting, the techniques used included deep planting at two different depths, and shading the lower stem. The differences in survival after 3 growing seasons were not statistically significant, but deep planting had helped height growth. Excellent survival in all treatments was probably the result of good stock, careful handling and planting, proper site preparation, and timely rainfall the first spring.

The optimum interval at which to plant tropical ash (Fraxinus uhdei) is being studied on the Waiakea Forest Reserve, island of Hawaii. Four spacing intervals are being tried: 6,8, 10, and 12 feet. Measurements of trial plots in 1969-8 years after plots were set up-suggest that (a) interval had not affected survival rate; (b) spacing had not affected diameter or height growth; (c) basal area per acre varied inversely with interval; and (d) spacing had not affected proportion of acceptable, desirable, and cull trees to total number of trees planted.

Creeping sage (Salvia sonomensis Greene), a semi-shrub, is useful for plantings to reduce fire hazard and to stabilize soil. The most effective, practical, and lasting technique to break seed dormancy was a soaking in gibberellic acid under constant agitation at 500 p.p.m. for 4 hours. Lesser concentrations of this acid and shorter soaking periods were satisfactory if the seeds were planted soon after treatment and if soil moisture and other conditions favored germination. Sulfuric acid, thiourea, hydrogen peroxide, hot water, and gibberellic acid slurry-used alone or in various combination...

Two traditional techniques of forest control and regulation-formulas and area-volume check-are compared to linear programing, as used in a new computerized planning system called Timber Resource Allocation Method ( Timber RAM). Inventory data from a National Forest in California illustrate how each technique is used. The traditional methods are simpler to apply and less expensive, but Timber RAM allows a more realistic definition of timber resources and can analyze a wider spectrum of forest management practices.

While the age distribution and species composition of North American avian breeding populations is reasonably well known, comparable information is generally not available on migrating populations. Capture data taken at the Point Reyes Bird Observatory on the coast at Bolinas, 23 km NW of San Francisco, and at other stations in California have provided information on the composition, seasonal timing, and relative abundance of various species of land bird migrants.