Treesearch

This report assembles the results of a number of small exploratory studies on the extraction, storage, and viability testing of pollen of several species of pines. These studies indicate clearly the need for more knowledge of the physiology of pollen — particularly of the relation between atmospheric humidity at the time of pollen shedding and the subsequent reactions of the pollen to environmental conditions.

This study was designed to obtain thermal conductivity of som common forest fuels which hitherto had defied such efforts because of their shape, size, or structure. Dry leaves and decayed. wood (punk) were modified so that conductivity measurements could be made by a thin plate uni-directional heat flow calibration stand, Resultss of these measurements are compatible with a linear relationship between thermal conductivity and specific gravity, established by MacLean, and indicate that conductivities of most common forest fuels may be determined from their specific gravities, MacLean's...

Forest fuels are heterogeneous mixtures of a number of green and dead woody substances. Most common are leaves, grass, conifer needles, moss, bark, and wood. As a result of past fires, an area may also contain some charcoal. With the exception of charcoal, these materials are in various stages of decay or decomposition. Logs, limbs, and decayed wood in an advanced stage of decay are referred to as punk. Mixtures of decayed needles, leaves, and grass are usually called duff.

Records of permanent sample plots and extensive observations by forest management research workers indicate that tree selection methods of cutting in sugar pine-fir types have not favored the establishment of sugar pine reproduction. Since sugar pine is a highly prized lumber producing species in the California region, special measures to preserve or increase its place in the stand were made part of an experimental logging project on the Stanislaus Experimental Forest in 1948 and 1949. This project was a combination field test and demonstration of unit area control, a silvicultural system...

Epicormic branches have developed on white fir (Abies concolor) one to two years after part of the live limbs were removed in a pruning experiment. The appearance of an average of six epicormic sprouts per tree raises some doubt as to the desirability of planting this species.

Reducing logging damage to reproduction and residual stands is an important part of harvesting the old-growth forests of California. Much of the over mature timber: is on areas with an acceptable stocking of advance growth. When the old trees are harvested, the advance growth is scarred, deformed, broken, or killed outright. Insects and disease attack the broken and scarred trees, and the quantity and quality of wood grown for the next harvest is reduced. Sometimes the advance growth is so severely damaged that the stand must be regenerated. This is costly and of course extends the time...

There is a definite distinction between the basic concept of unit area control and the specific techniques or treatments used for specific units. Unit area control as a term was first used in connection with a cutting trial in the sugar pine-fir type; consequently, many foresters think the term refers merely to the technique used in sugar pine management, This is not the case, Applying silviculture unit areas is appropriate and desirable for other major types as well. So far, however, techniques have been developed only for pine and mixed-conifer types in the Sierra Nevada. The remainder...

Direct seeding is a highly desirable method of regeneration. It is more economical and more flexible in both time and place than the planting of trees. In California, however, direct seeding generally has been an ineffective method of regeneration. Early trials by the Forest Service with broadcast sowing and spot sowing invariably failed to produce an adequate stand of reproduction primarily because forest rodents destroyed the seed or seedlings. Poisoning and trapping had little effect. Protecting seed spots with screens was judged to be effective but not economical. More recently direct...

Natural reproduction must provide future crops of timber on most of the forest land being placed under management in California. Relatively few acres will be planted or seeded in the near future because planting costs are high, facilities for undertaking large-scale planting are inadequate, and direct seeding has not yet proved satisfactory. In the pine region it is desirable that reproduction stands be adequately stocked with vigorous pine seedlings. How promising is the outlook for natural restocking. The degree of success in one important locality is the subject of this paper. It...

Instructions for establishing fire-weather stations in Region 5 have usually specified that the fuel-moisture indicator sticks be placed over a bed of ponderosa pine needles. This specification was made to insure uniform ground-cover effect for all stations. Because ponderosa pine needles are not readily available in all areas of California fire control technicians have often asked if pine needles must be used in preference to local litter types.