Treesearch

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

In a low-phosphate medium fosetyl-Al showed a much higher activity in vitro against Phytophthora than previously reported in the literature. Both fosetyl-Al, and more particularly phosphorous acid (H3PO3), were highly inhibitory in vitro against several species of Phytophthora. Phosphorous acid was much less inhibitory in vitro against Pythium and had only low activity against a selection of non-oomycetous fungi. The EC50 values for an isolate of Phytophthora cinnamomi, cultured on a low phosphate medium, were 0.05 PO3 meq of H3PO3 (4 μg/mi) and 0.45 PO3 meq of fosetyl-Al per liter (54...

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 (R2) 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 - Solution and landsliding, the dominant erosion processes in undisturbed forested mountainous watersheds, are both influenced by subsurface drainage. Biological processes that generate organic acids accelerate loss of dissolved solids by promoting the dissolution of primary minerals in granitic rock. These organic acids can also disperse the secondary minerals, kaolinite and ferric hydroxide. This accelerates erosion by subsurface drainage through suffusion and piping, particularly in well-drained, gap-graded soils. Solution, suffusion, and piping on steep slopes can promote...