Treesearch

Pertinent literature on the biological aspects of annosus root disease is reviewed. Key features of the life cycle of Heterobasidion annosum such as stump infection, stump colonization, host-parasite relations, and interactions of various physical and biological factors are discussed in relation to forest stands in the western United States. This review suggests our knowledge of the pathology of this disease is limited on most affected tree species. Further research on various aspects of the life cycle of this fungus is essential to minimizing losses to this disease.

Recent advances in the genetics and population biology of Heterobasidion annosum are reviewed. H. annosum is a heterothallic (outbreeding) basidiomycete with a unifactorial, multiallelic incompatibility system which regulates mating. H. annosum in western North America consists of two intersterility groups (biological species) which can be identified through mating tests and isozyme analysis. Intersterility groups in western North America appear to be host specific. Intersterility between groups is attributable to specific genes. Intergroup hybrids have been formed in the laboratory, but...

The California Department of Conservation, Division of Mines and Geology provided technical assistance to the California Department of Forestry and Fire Protection in assessing potential geologic hazards that could be affected by proposed prescribed burns on Mt. Tamalpais. This research yielded the following conclusions: (1) landsliding and surface erosion have contributed to the denudation of Mount Tamalpais; (2) Debris flows and surface erosion could affect property and the environment on and below the mountain; (3) The removal of chaparral will reduce the stability of the slopes; and...

Fires were a part of our wildlands prehistorically. Prescribed burning reduces fire hazard and potential fire behavior primarily by reducing fuel quantity and continuity. Fuel continuity should be considered on the micro scale within stands, the mid-scale among, and the macro-scale among watersheds or entire forests. Prescribed fire is only one of the tools which can be used to reduce fire hazard, but it can be effective at all scales.

Prescribed burning for fire hazard reduction in the chaparral is predicated on the belief that young fuels (20 years old and less) are highly resistant to burning. To test this belief, a data base search of large fires in San Diego County between 1940 and 1985 was conducted to locate reburns of young chaparral fuels greater than 1000 acres (400 ha) in extent. Of the 147 fires examined, 17 (11.6 percent) contained at least one area of young fuels that had reburned. The majority of the reburns occurred under severe weather conditions. The finding that young fuels do not necessarily inhibit...

The distribution of Plecoptera along a California river was used to test several predictions of the River Continuum Concept about how functional feeding groups should change along a stream's length. Stoneflies were collected from stream orders 1-6 (123 km) of the Cosumnes River continuum in the central Sierra Nevada. The 69 stonefly species collected were separated into three functional feeding groups – 26 shredders (detritivores), 39 predators (engulfers), and 4 scrapers. Stonefly shredders and predators reached maximum species richness at middle stream orders (3-5). The relative abundance...

The fires of 1987 had a heavy impact on the Hayfork Ranger District. Over 50,000 acres were burned within the South Fork Trinity River watershed, which contains an important anadromous fishery. Major problems within the burned area were found to be: (1) slopes having highly erodible soils where intense wildfire resulted in a total loss of ground cover, and (2) burnout of the natural woody sediment barriers in stream channels. Emergency watershed treatments included aerial seeding of selected slopes with species selected for their ability to germinate quickly and re-establish ground cover....

Timber salvage on the Indian Burn was carried out without compromising watershed values. In some cases watershed condition was actually improved by providing ground cover, by removing trees that were a source of erosive water droplets, and by breaking up hydrophobic soil layers. Negative impacts of timber salvage on watersheds were minimized by using an interdisciplinary team that identified issues, concerns, and opportunities early, defined specific objectives for each resource, had access to accurate site information, and developed management prescriptions in the context of whole...

Wildfires traditionally have been regarded as a threat to many of the multiple resources produced by forest lands. Timber, fish, recreation, and water are all important forest products that can be adversely affected by wildfires. The greatest threat, however, is to the long-term productivity of the land. Foresters are particularly aware of this threat because the production of their primary crop--trees--is such a long-term endeavor.

Aerial seeding of Italian annual ryegrass (Lolium multiflorum) is a common, but controversial, emergency rehabilitation practice following wildfire in California. Replicated study plots, with and without ryegrass, established after a summertime chaparral wildfire on California's central coast revealed the following: 1. Ryegrass-seeded plots developed significantly greater total plant cover than unseeded plots in the first year. 2. Regeneration and growth of native species were significantly depressed in the presence of ryegrass. 3. Soil erosion was significantly greater on ryegrass-seeded...