Treesearch

Stylized fuel models, or numerical descriptions of fuel arrays, are used as inputs to fire behavior simulation models. These fuel models are often chosen on the basis of generalized fuel descriptions, which are related to field observations. Site-specific observations of fuels or fire behavior in the field are not readily available or necessary for most fire management planning situations. Fuels are thought of in general terms and a single fuel model is often assigned to represent large areas of land. Variations in weather, which can substantially affect fire behavior, are not reflected in...

In the last decade, the fire management program of the Forest Service, U.S. Department of Agriculture, has come under closer scrutiny because of ever-rising program costs. The Forest Service has responded by conducting several studies analyzing the economic efficiency of its fire management program. Some components of the analytical models have been difficult to develop, particularly changes in the net value and output of timber caused by wildfire.

Advance regeneration is common under decadent, old-growth stands of California red fir (Abies magnifica A. Murr.). Intense competition for the site's resources can create sapling stands of poor vigor and advanced age. When competition is reduced by overstory removal and thinning, suppressed advance regeneration has been shown to respond with increased growth. But, to select leave trees, land managers need to know which tree characteristics we associated with growth after release and thinning. This paper reports those easily measured tree characteristics found to be most closely associated...

After 100 years of fire exclusion, controlled burning in the fall was used as a first step in the reintroduction of periodic burning in a southwestern ponderosa pine ecosystem near Flagstaff, Arizona, U.S.A. Organic matter storage in woody debris was decreased 63 percent from 2,325 g/m² to 869 g/m², with a disproportionate (99 percent) decline in the large, rotten wood. Nutrient storage in the woody debris decreased by 80 percent for N, 62 percent for P, 70 percent for Ca, 71 percent for Mg, and 74 percent for K. Forest floor storages were less drastically affected, with organic matter...

A series of tracer experiments were carried out as part of the Atmospheric Studies in Complex Terrain (ASCOT) program to evaluate pollutant transport and dispersion characteristics of nocturnal drainage flows within a valley in northern California. The results indicate that the degree of interaction of the drainage flows with the larger scale regional flows are strongly dependent on how well the shallow drainage flows are shielded by the surrounding topography from the external environment. For the valley under study, the drainage flows from about mid-slope elevations and below were...

Since the early 1900s, four major infestations of the koa moth, Scotorythra paludicola (Butler), have defoliated koa (Acacia koa Gray) stands on the island of Maui. After trees on 7564 ha of the Makawao Forest Reserve were damaged in 1977, a study was begun to determine growth and refoliation response of completely defoliated trees in a stand previously subjected to three different silvicultural treatments. Relative growth rates before defoliation ranged from 5.7 percent to 14.2 percent per year. Trees on thinned-and-fertilized plots showed significantly greater relative growth rates than...

Koa (Acacia koa) is the most valuable native timber species in Hawaii. Bark stripping of young trees by rats, a common but unstudied phenomenon, may affect survival, growth, and quality of koa. Up to 54% of the trees sampled in 4- to 6-year-old stands in the Laupahoehoe and Waiakea areas on Hawaii were wounded by rats; only 5% of trees sampled in a l-year-old stand on Borge Ridge, Maui, were wounded. Wounds were generally long and narrow. Complete girdling was not observed, and direct mortality seemed low. However, indirect effects of damage-deformation of stems, infection by pathogens,...

Field workers doing surveys, control operations, and research on western spruce bud worm often encounter other kinds of foliage-feeding larvae, some of which closely resemble western spruce bud worm , Workers must be able to distinguish between the different species and groups.

Prescribed burning was used to improve blacktailed deer (Odocoileus hemionus columbianus) habitat in Trinity County, northern California. Deer response was measured by comparing pellet group deposition on one burned and three unburned areas. Pellet group counts were highest on the burned area for 3 years after burning. One year after burning, pellet group deposition on one unburned areas was lowest adjacent to the burned area and increased with distance from the burned area. Using control areas adjacent to the burn led to an overestimate of increase in deer activity. Prescribed burning...