Treesearch

Flame geometry plays a key role in shaping fire behavior as it can influence flame spread, radiative heat transfer and fire intensity. For wildland fire, thorough characterizations of flame geometry can help advance the derivation of comprehensive models of wildfire behavior. Within the fire community, a classical flame modeling approach has been to develop semi-empirical models. Many of these models have been derived for surface fuels or for pool fire configurations. However, few have sought to model flame behavior in chaparral crown fires. Thus, the objective of this study is to assess...

Background Understanding the temporal patterns of fire occurrence and their relationships with fuel dryness is key to sound fire management, especially under increasing global warming. At present, no system for prediction of fire occurrence risk based on fuel dryness conditions is available in Mexico. As part of an ongoing national-scale project, we developed an operational fire risk mapping tool based on satellite and weather information. Results We demonstrated how differing monthly temporal trends in a fuel greenness index, dead ratio (DR), and fire density (FDI) can be clearly different...

A bird observatory is a research and education institution whose overall and primary mission is typically to provide information on the life history and conservation of birds. Originally known as the Point Reyes Bird Observatory (PRBO), this institution has survived and flourished since its founding more than 50 years ago. Known in later years as Point Blue Conservation Science, it has been led and staffed by a camaraderie of dedicated and inspired people. It has also provided important leadership in field ornithology and related fields of natural history, and most importantly, as a leader...

The chaparral restoration workshop held in Arcadia, CA, in 2013 brought together experts, managers and others to discuss alternatives that more effectively protect, manage and even revegetate diminishing shrublands. This publication is a compilation of some of the workshop and oral presentations that update our current knowledge of shrubland ecology and management with respect to its loss and recovery. Shrubland species have evolved strategies that allow them to endure Mediterranean climate extremes. Combinations of often complex factors allow these plants to survive unpredictable and...

Comparisons between historical and current conditions indicate that modern red fir (Abies magnifica) and subalpine forests of the Sierra Nevada bioregion are largely within their natural range of variation (NRV) with respect to compositional, functional, and some structural variables. Exceptions common to both forest types include a considerable shift in the tree size class distribution to smaller diameters, decrease in large-diameter tree densities (e.g., red fir, lodgepole pine [Pinus contorta], western white pine [P. monticola]), and greater homogenization of forest structure at both...

Wildland fire, which includes both planned (prescribed fire) and unplanned (wildfire) fires, is an important component of many ecosystems. During wildland fires, low heating rate pyrolysis (slow pyrolysis) occurs during preheating and/or smoldering of plant material. High heating rate pyrolysis (fast pyrolysis) exists in the flame region. Pyrolysis temperature and heating rate play important roles on the yields and the compositions of pyrolysis products. In this work, the effects of pyrolysis temperature and heating rate on the yields and the compositions of pyrolysis products from 14...

Volatile organic compounds (VOCs) are emitted from many sources, including wildland fire. VOCs have received heightened emphasis due to such gases’ influential role in the atmosphere, as well as possible health effects. We have used extractive infrared (IR) spectroscopy on recent prescribed burns in longleaf pine stands and herein report the first detection of five compounds using this technique. The newly reported IR detections include naphthalene, methyl nitrite, allene, acrolein and acetaldehyde. We discuss the approaches used for detection, particularly the software methods needed to...

Ambient soil temperatures were measured every four weeks from May 1986 to November 1986 at three depths under the organic forest floor in ponderosa pine (Pinus ponderosa Lawson & C. Lawson) forests in three stand types subjected to periodic prescribed burning. Temperatures at the organic layer – soil surface interface in sawtimber stands were higher and more variable than in pole and saplings stands. Temperature variability reached a maximum in the summer and decreased into the fall and early winter. Soil temperature variability decreased as depth below the surface increased. Three years...

Before widespread fire exclusion policies, American Indians used broadcast understory fires or cultural burns to enhance resources integral for their livelihood and cultural practices. To restore ecocultural resources depleted from decades of fire exclusion and to reduce wildfire risks, the Karuk and the Yurok Tribes of Northwest California are leading regional collaborative efforts to expand broadcast fires and fuel reduction treatments on public, private, and Tribal lands in their ancestral territories. Through collaboration with Karuk and Yurok Tribal members and basketweavers, we...

Smoke from human-induced fires such as prescribed fires can occasionally cause significant reduction in visibility on highways in the southern United States. Visibility reduction to less than 3 m has been termed "superfog' and environmental conditions that lead to its formation have been proposed previously. Accurate characterization and prediction of precursor conditions for superfog is needed to prevent dangerous low visibility situations when planning prescribed fires. It is hypothesized that extremely hygroscopic cloud condensation nuclei from the smoldering phase of a fire can produce...