Treesearch

Overstocked 70- to 90-year-old stands of ponderosa pine on medium- to low-quality sites were thinned in 1980 to 40, 55, and 70 percent of normal basal area and compared to an unthinned control. Mortality, diameter, and height in these northern California stands were measured annually from 1980 to 1987. After 8 years, mortality, primarily from mountain pine beetle (Dendroctonus ponderosae) and annosus root disease (Heterobasidion annosum), was reduced 100, 95, and 86 percent relative to increasing amounts of reserve basal area. Thinned stands averaged five times more cubic-foot volume...

Seasonal differences in use of food and habitat have been shown for numerous bird species. Especially during winter, when insect food is often at its lowest availability, birds may be unable to secure enough food for survival. In earlier work in the mixed-conifer zone of the western Sierra Nevada (Blodgett Forest, El Dorado County), observers found that many birds significantly increased their relative use of incense-cedar (Calocedrus decurrens [Torr.] Florin.) for foraging in winter as compared to summer. Preliminary examination of cedar showed the presence of one predominant arthropod...

Baseline levels for densities of snags (standing dead trees) wered etermined in undisturbed old-growth stands on the Gasquet Ranger District. Six Riven National Forest, California. Snag species, number, diameter at breast height (d.b.h.), height, cavity type, cavity use, decay class, and snag origin were recorded on 317 plots over a 2-year period. The 2121 snags recorded consisted of Pseudotsuga menziesii (36 percent), Abies concolor (29 perecnt), Abics mgnifica var. sharlemis (7 percent), Pinus lambertiana (4 percent), Chamaecyparis lawsonina (6 percent), hardwoods (10 percent), and other...

Two hydrologic models were adapted to estimate postfire changer in water yield in Pacific Northwest watersheds. The WRENSS version of the simulation model PROSPER is used for hydrologic regimes dominated by rainfall: it calculates water available for streamflow onthe basis of seasonal precipitation and leaf area index. The WRENSS version of the simulation model WATBAL is used for hydrologic regimes dominated by snowfall; it calculates water available for streamflow based on seasonal precipitation, energy aspect and cover density. The PROSPER and WATBAL models estimate large postfire...

Assessing the trade-offs between market and nonmarket products of wildlands poses a major problem fornatural resource planners and managers. Scenic quality is a resource that is not quantifiable in monetary terms. To determine if market values of real estate offering views could define relative dollar values for physical dimensions and objects in views, they were correlated to real estate prices for 13 recreation subdivisions in California wildlands. View variables were related to lot values in each subdivision, but the specific view variables related to value varied greatly among subdivisi...

Comparisons between abnormal and normal sprout clumps of tanoak (Lithocarpus densiflorus [Hook. & Am.] Rehd.) in northern California indicated that sprouts in abnormal clumps had about five times the number of sprouts per dump, were three times as wide, and only one-fifth as tall. Stunted and chlorotic sprouts were examined for virus and disease organisms that might be used for biological control of this often weedy species. No pathogens or viruses that could account for the abnormal development were found in field or laboratory. but tests were not exhaustive. Decline could be from...

Recent measurements indicate significantly enhanced biogenic soil emissions of both nitric oxide (NO) and nitrous oxide (N2O) following surface burning. These enhanced fluxes persisted for at least 6 months following the burn. Simultaneous measurements indicate enhanced levels of exchangeable ammonium in the soil following the burn. Biomass burning is known to be an instantaneous source of NO and N2O resulting from high-temperature combustion. Now we find that biomass burning also results in significantly enhanced biogenic emissions of these gases, which persist for months following the burn.

Abstract - Storm yields of water and sediment are being measured as part of a study of the effects of roading, logging, and burning in a second-growth redwood forest in northern California. Two primary basins, each about 500 ha, and 13 sub-basins in one of them are measured for sediment flux and the presence and magnitude of sediment-based ""cumulative effects"". Study objectives require a more sophisticated sediment sampling design than typically used in watershed experiments. Sediment is sampled and estimated by using PSALT - a probability-based method for sampling that enhances data...

The San Dimas Experimental Forest serves as a field laboratory for studies of chaparral and related ecosystems, and has been recognized by national and international organizations. It covers 6,945 ha (17,153 acres) in the foothills of the San Gabriel Mountains northeast of Los Angeles, and has a typical Mediterranean-type climate. The Forest encompasses the San Dimas and Big Dalton watersheds, which have vegetation typical of southern California, are separated by deep canyons from the rest of the San Gabriel Mountains, have small tributaries suitable for study, and are harnessed by flood...