Treesearch

Ammonium-based fire retardants are important in managing wildfires, but their use can adversely affect water quality. Their entry, fate, and impact were studied in five forest streams. Initial retardant concentrations in water approached levels which could damage fish, but no distressed fish were found. Concentrations decreased sharply with time after application and distance downstream, and there was no long-term entry. The numbers and kinds of stream insects were not affected. Simulations of retardant dispersal in streams showed fish mortality might occur from zero to more than 10,000 m...

Adjacent headwater streams were monitored for postfire shade, summer streamflow and maximum water temperature following the 40,000 ha Silver Complex fire in southern Oregon. Average postfire shade (30 percent) for the three streams was considerably less than prefire shade (est.>90 percent). Dramatic increases in direct solar radiation resulted in large but variable increase in maximum water temperature. Increase was greatest in Stream C where temperature increased 10.0°C. Stream B increased 6.2°C. Stream A increased 3.3°C.

SAC88 is a major revision of the Sacramento Model, which was developed in 1969 with minor revisions through 1973. Two of many 1988 changes make it possible to estimate hydrologic effects of a fire in a watershed where pre-fire parameters can be calibrated or estimated: (1) Evapotranspiration, treated as extracted from six root-zone layers under pre-fire conditions, may be limited to one to five layers in the burned area; (2) An infiltration-rate limiting value, large for an unburned area, may be substantially reduced for an area where high soil temperatures and ash are thought to have...

Effects of brush fire on hydrologic characteristics of chaparral watersheds were analyzed. An unburned chaparral produces moderate surface runoff. The vegetation promotes infiltration by retarding the runoff and providing temporary storage during intense rainfall. The hydrologic characteristics of chaparral watershed, however, are drastically changed by fires. The high rate of runoff following brush fires may result from the combined effects of denudation and formation of a water-repellent soil layer beneath the ground surface. This layer greatly decreases infiltration rates and reduces...

Wildfires and prescribed burns are common throughout Arizona and California chaparral. Predicting fire effects requires understanding fire behavior, estimating soil heating, and predicting changes in soil properties. Substantial quantities of some nutrients, particularly nitrogen and phosphorus, are lost directly during combustion. Highly available nutrients released during a fire are deposited on the soil surface where they are immobilized or lost by erosion. Information on the effect of fire on physical, chemical, and biological soil properties provides a basis for discussing short- and...

The Angel Fire of September, 1987 caused extensive damage to second growth forest in the south fork drainage of Cow Creek, 55 km northeast of Grant's Pass, Oregon, USA. The fire was characterized by a high-intensity burn over areas of steep topography. The areal distribution of soil hydraulic properties in a small, tributary watershed following high-intensity wildfire is examined using tests of infiltration capacity, saturated hydraulic conductivity, and soil moisture characteristics. Also, measures of soil water-repellency are determined. Soil hydraulic properties are evaluated for logged...

Recognizing annosus root disease affecting conifers in northwestern United States forests is discussed. Field diagnosis can bemade by observing characteristic stand patterns, wood stain and decay, ectotrophic mycelium, and sporophores. Most seriously affected trees include hemlocks, grand fir, white fir and Pacific silver fir. Ponderosa pine and other true firs may also be damaged. Wounded trees, especially hemlocks and true firs, are readily colonized by Heterobasidion annosum and wounds can be used as an indicator of infection. Laboratory analysis can be used to confirm field diagnosis.

Rapidly chancing land use patterns are having a significant impact on watershed management and the included elements of fuel management and fire protection. The complexity of watershed management was defined in the Watershed Management Council's publication prepared for the first conference. This publication, California's Watersheds, emphasized that all land use activity has an impact, that individual impacts can be cumulative and even synergistic. In California, the impact of development on fire effects and fire protection is a grand example.

Fire management has always meant fire suppression to the managers of the chaparral covered southern California National Forests. Today, Forest Service fire management programs must be cost effective, while wilderness fire management objectives are aimed at recreating natural fire regimes. A cost-effectiveness analysis has been developed to compare fire management options for meeting these objectives in California's chaparral wilderness. This paper describes the analytical procedure using examples from a study currently being conducted for the Los Padres National Forest, and discusses some...

Stand patterns of annosus root disease include various degrees and patterns of tree mortality; tree crown, root collar, and root symptoms; and the condition and location of stumps. In the Intermountain states of Montana, Idaho, and Utah, annosus root disease is found in the ponderosa pine, mixed conifer and high-elevation fir forests. Stand patterns are of value in diagnosing the disease in each of these forest types, but other root pathogens may cause similar symptoms. Confirmation of annosus root disease depends upon further steps in the diagnosis process.