Treesearch

Large fires pose risks to a number of important values, including the ecology, property and the lives of incident responders. A relatively unstudied aspect of fire management is the risks to which incident managers are exposed due to organizational and sociopolitical factors that put them in a position of, for example, potential liability or degradation of their image as a leader. This paper explores the hypothesis that the concept of risk in large fire management extends beyond the potential for physical harm and includes perceived potential damages in the form of social harm that can...

The abandonment of land, the high energy load generated and accumulated by vegetation covers, climate change and interface scenarios in Mediterranean forest ecosystems are demanding serious attention to forest fire conditions. This is particularly true when dealing with the budget requirements for undertaking protection programs related to the state of current and future forest landscapes. Based on economic analysis, suppression costs represent a significant proportion of the total budget available for forest fire protection programs. The need to make efficient use of available budgets...

To better evaluate the potential impacts of wildland fire in the San Bernardino National Forest, we developed a geographic information system (GIS) data layer containing nonmarket economic values for the San Jacinto Ranger District. Each pixel in the data layer contains an estimate of the most prominent nonmarket values at that location. This information can be used by forest managers as a decision making aid when deciding how to allocate resources to protect high value areas. To estimate the recreation value component and potential losses due to wildfire, backcountry hikers entering the...

Non-native diseases of dominant tree species have diminished North American forest biodiversity, structure, and ecosystem function over the last 150 years. Since the mid-1990s, coastal California forests have suffered extensive decline of the endemic overstory tree tanoak, Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh (Fagaceae), following the emergence of the exotic pathogen Phythophthora ramorum and the resulting disease sudden oak death. There are two central challenges to protecting tanoak: 1) the pathogen P. ramorum has multiple pathways of spread and is thus...

The combination of sprouting and reproduction by seed can have important consequences on fine-scale spatial distribution of genetic structure (SGS). SGS is an important consideration for species’ restoration because it determines the minimum distance among seed trees to maximize genetic diversity while not prejudicing locally adapted genotypes. Local environmental conditions can be expected to influence levels of clonal spread and SGS, particularly in the case of disturbance regimes such as fire. Here, we characterize fine-scale genetic structure and clonal spread in tanoak from drier...

Over a century of fire suppression activities have altered the structure and composition of mixed conifer forests throughout the western United States. In the absence of fire, fuels have accumulated in these forests causing concerns over the potential for catastrophic wildfires. Fuel reduction treatments are being used on federal and state lands to reduce the threat of wildfire by mechanically removing biomass. Although these treatments result in a reduction in fire hazard, their impact on wildlife is less clear. We use a multi-species occupancy modeling approach to build habitat-suitabilit...

Background: As a result of past practices, many of the dry coniferous forests of the western United States contain dense, even-aged stands with uncharacteristically high levels of litter and downed woody debris. These changes to the forest have received considerable attention as they elevate concerns regarding the outcome of wildland fire. However, attempts to reduce biomass through fuel reduction (i.e., thinning of trees) are often opposed by public interest groups whose objectives include maintaining habitat for species of concern such as the spotted owl, Strix occidentalis, the northern...

Due to the aquatic nature of oomycetes, Phytophthora spp. can be found in a wide variety of waterways in and around natural and agricultural ecosystems—including forest streams, urban streams, and irrigation ponds. They are disseminated effectively and efficiently in flowing water, so Phytophthora spp. can be moved readily from an infested area (e.g., a nursery) to nearby non-infested environments if waterways in the infested area become contaminated with propagules of the pathogen. This type of dissemination—particularly for exotic species like P. ramorum—poses a serious threat to plants...

In Oregon, efforts to eradicate Phytophthora ramorum from forested areas have included use of herbicides to kill infected plants. Use of herbicides on disease-infected plants leads to various outcomes, from decreased spread of disease to greater spread of disease, depending on the plant-pathogen system being examined. In this study, viburnum (Viburnum) cuttings, rhododendron (Rhododendron) cuttings, and chestnut oak (Quercus prinus L.) seedlings were treated with herbicides at standard application rates for woody shrubs 4 days after their roots had been infected with P. ramorum. The amount...

The objective of our research was to determine the environmental conditions and lesion age favorable for Phytophthora ramorum sporulation under field conditions. For 2 years, new camellia, rhododendron, and California bay laurel (Umbellaria californica (Hook. & Arn.) Nutt.) nursery stock were seasonally inoculated (every 3 months) on foliage. They were covered overhead to prevent rainfall from falling on the plants, but otherwise the plants were completely open to the natural environment. Consistent leaf wetness periods were produced with overhead misting systems and controlling sensors to...