Treesearch

Koa is Hawaii's finest native timber tree. Unfortunately, it grows best in areas that can be converted into good grazing land, and most of the best koa forests have been cleared to develop pasture. Consequently, not much koa is left. Koa seedlings are also palatable to grazing animals, so that the number of young, vigorous koa trees is small.

To convert old-growth redwood (Sequoia sempervirens) to younger managed stands, three types of regeneration cuttings are being tried at the Redwood Experimental Forest, northern California: clearcutting, shelterwood, and selection cutting. Logging mortality was heavy for all tree sizes and greatest where the heaviest cuts were made. The large size of a negative net growth of sawtimber on selection cuttings is attributed to mortality during a 10-year postlogging period. Net growth was slightly negative on shelterwood cuttings. By the end of the 10 years, basal area growth for saplings on...

Ten species of Mexican pines were planted on adverse sites at 6450 feet (1970 m) elevation on Maui, and five species on similar sites at 3200 feet (975 m) elevation on Molokai, Hawaii. Initial survival was poor because of the low quality of the planting stock and harsh site conditions, but subsequent mortality was low. Growth and vigor has been satisfactory. Average annual height growth five years after outplanting ranged from 1 to 3 feet 0.3 to 1 m) on Maui and from 1 to 2 feet (0.3 to 0.6 m) on Molokai. Most trees showed good vigor. The results suggest that Mexican pines would be...

Cutting by the minimum standard of the Rules of California's North Sierra Pine Forest District was evaluated for effects on species composition, seed fall, regeneration, and residual growth at the Challenge Experimental Forest, central California. Cutting removed 74 percent of the stand basal area and 94 percent of the merchantable volume. The heavy cut changed the species composition from primarily ponderosa pine to hardwoods and tolerant conifers. Sound seed was deficient in quantity, although trees in the cut blocks produced more seed than did trees in the control. Regeneration of...

Heights of permanent sample trees with tops visible from any point can be measured from that point with any clinometer, measuring one vertical angle per tree. Two horizontal angles and one additional vertical angle per observation point are necessary to orient the point to the plot. Permanently recorded coordinates and elevations of tree locations are used with the angles to calculate the instrument location and elevation, instrument-to-tree distance, and total tree height. The method is efficient only if a programmable calculator or a computer can be used for calculations. Procedures and...

A dynamic fuel model for the chaparral brush fields of southern California shows that (a) the fire threat for the first few years after a fire primarily is related to forbs and grasses; and (b) after 10 to 20 years, the brush fields will sustain very fast-spreading, high-intensity fires, depending upon the ratio of the live-to-dead fuel. The mathematical models described permit systematic analysis of the consequences of fuel treatment and fire control and projection of these consequences for the future.

Samples of ordinary “ash-free” cellulose papers and similar samples decrystallized by swelling in liquid ammonia were pyrolyzed in vacuo to a weight loss ranging from

An earIier numerical analysis showed that the second approximate method of Horotitz and Metzger can be rendered exceedingly accurate for reduction of thermo-gravimetry data. It is demonstrated here that this result can be justified on the basis of an asymptotic expansion with a nondimensional activation energy as the large parameter. The order of magnitude of the error is ascertained for this and two other approximate methods. Higher-order terms in the approximation are developed.