Treesearch

The effects of tree spacing and brush competition were evaluated on a ponderosa pine (Pinus ponderosa Dougl. ex Laws. var. ponderosa) site of low productivity in California's North Coast Range. Eleven-year-old saplings were thinned to square spacings of 2.1, 2.4, 3.0, and 4.3 m (7, 8, 10, and 14 ft), and all, half, and none of the understory brush (principally manzanita [Arctostaphylos sp. J) manually removed in a split-plot design. Analysis of variance showed that brush crown cover was significantly related to periodic annual increment in diameter-at-breast-height, height, and volume of...

This report analyzes the procedures used in three regions of the Forest Service, U.S. Department of Agriculture, for selecting the projects that constitute their annual program budget. Personnel at the Southwest (R-3), Pacific Southwest (R-5), and Southern (R-8) Regions were interviewed during September and October 1982. Of special concern was the extent to which analytical methods are used that include an explicit and formal consideration of the relative costs and benefits of alternative program allocations. Current program development and budget processes were found to allow only limited...

Information on the regeneration of Douglas-fir, one of the most valuable timber species in the United States, is summarized, from seed production to care of young stands. General recommendations are given to guide the practitioner. Seed production can be increased by applying fertilizer and by stem girdling. To prepare sites for planting, mechanical, burning, chemical or a combination of treatments should be used. All details during each stage of the planting process should be followed. Steps should be taken to control vegetative competition and animal damage to seedlings and young trees....

In the past, decisionmaking in wildland fire management generally has not included a full consideration of the risk and uncertainty that is inherent in evaluating alternatives. Fire management policies in some Federal land management agencies now require risk evaluation. The model for estimating the economic efficiency of fire program alternatives is the minimization of the sum of fire management cost plus the fire-induced net value change in the resource outputs (C + NVC). Risk can be graphically displayed in this model by the addition of probability distributions about the C + NVC curve....

Careful selection of an experimental design for a bioassay substantially improves the precision of effective dose (ED) estimates. Design considerations typically include determination of sample size, dose selection, and allocation of subjects to doses. DOSESCREEN is a computer program written to help investigators select an efficient design for the estimation of an arbitrary ED. This report establishes the statistical basis for DOSESCREEN and suggests several ways to utilize DOSESCREEN out-put. A copy of the computer program in Fortran 77 is provided so users can easily convert DOSESCREEN...

Potential fire characteristics can be estimated as functions of weather, fuel, and terrain slope. Such information is needed by forest and other land managers--especially for anticipating fire suppression needs and planning prescribed burns. To provide this information, an Atlas has been developed for California. The Atlas includes statistical analyses of spread component, burning index, ignition component, temperature, relative humidity, dead fuel moisture, live woody fuel moisture, live herbaceous fuel moisture, precipitation, windspeed and direction for 200 fire-danger rating stations...

A classification system for use in describing vegetation has been developed for Hawaii. Physiognomic and taxonomic criteria are used for a hierarchical stratification of vegetation in which the system categories are Formation, Subformation, Series, Association, and Phase. The System applies to local resource management activities and serves as a framework for resource assessment reporting as it relates to vegetation. Although developed for Hawaii, the system can be applied to other Pacific islands.

Although erosion-hazard ratings are often used to guide forest practices, those used in California from 1974 to 1982 have been inadequate for estimating erosion potential. To improve the erosion-hazard rating procedure, separate estimating equations were used for different situations. The ratings were partitioned according to yarding method, erosional process, and both yarding method and erosional process. Partitioning by yarding method resulted in a slight improvement in the precision of erosion estimates. The other two methods resulted in fourfold increases in prediction errors. Results...

The relationship between measures of site disturbance and erosion resulting from timber harvest was studied by regression analyses. None of the 12 regression models developed and tested yielded a coefficient of determination (R 2) greater than 0.60. The results indicated that the poor fits to the data were due, in part, to unexplained qualitative differences in disturbance associated with cable and tractor yarded harvests. Improved prediction might be achieved by weighting each elementary area of disturbance by the sine of its slope for estimates of surface erosion and by both the sine of...

Abstract - To document a relationship between progressive hillslope deformation and precipitation, boreholes on the Redwood Creek basin in northern California were surveyed semiannually from 1974 to 1982. Regressions were calculated between borehole displacement and an antecedent precipitation index (API) variable. Values for the API variable were obtained by summing daily API values over the time between borehole surveys, if the daily API value exceeded some threshold