Treesearch

Under severe fire weather conditions arson is believed to be the primary cause of large wildland fires in southern California. Wildland fire suppression personnel and the public use the the expression "This weather brings out the arsonists" to indicate their awareness of the high potential for large arson-caused fires under these conditions. To determine the accuracy of this statement, fire occurrence and weather data were analyzed for four southern California National Forests for a 10-year period (1975–1984). The results showed that the proportion of arson and non-arson person-caused...

Shade at bus stops can enhance the thermal comfort of waiting riders and can encourage new passengers, thereby reducing air pollution and traffic congestion. This study used computer simulation to compare the cost-effectiveness of shade provided by metal shelters versus trees at 64 bus stops in Tucson, Arizona. The 40-year projected total future and present values of costs were over 50% greater for shelters than for trees. When differences in the amount of shade provided over time were considered, a 20% cost savings was projected for trees. Expenses for irrigation and pruning accounted for...

Predicting the movement of people into rural wildlands previously has been limited to studies of population and housing growth in counties or other large geographical areas. In these studies, the areas of high fire danger that contain dispersed rural housing cannot be distinguished from the areas less vulnerable to wildfire (small towns and adjacent urban areas) because the data and the analysis procedures associated with the l 980 census does did not give sufficient information about rural and wildland areas. Analysis studying rural demographics supplement census data with information...

Chaparral is a shrubby, sclerophyllous vegetation type that is common in middle elevations throughout much of California. It occupies 3.4 Mha throughout the state in some of the steepest terrain and adjacent to some of the most populated urban areas. Although chaparral has little direct commodity value, it does have great value in slope stabilization, watershed cover, wildlife habitat, and nutrient cycling. Combined effects of the summer-dry climate and the high flammability of chaparral vegetation render it extremely susceptible to periodic crown fires. Fires in the urban interface not...

Economic accountability concerns for wildfire prevention planning have led to the development of an ignition management approach to fire problems. The Fire Loss Prevention Planning Process (FLPPP) systematizes fire problem analyses and concomitantly establishes a means for evaluating prescribed prevention programs. However, new users of the FLPPP have experienced difficulty with both understanding and implementation. Consequently, an on-line tutorial is being developed for delivery of the rationale and methods of the FLPPP. This format takes the form of a knowledge-based intelligent...

Dimensional analysis has potential to help explain and predict physical phenomena, but has been used very little in studies of wildland fire behavior. By combining variables into dimensionless groups, the number of variables to be handled and the experiments to be run is greatly reduced. A low velocity wind tunnel was constructed, and methyl, ethyl, and isopropyl alcohol were used as buoyancy sources. Three diameters of pans, 4, 10, and 15 cm, were used and the order of six wind speeds was randomized in three replications. Flame angle was plotted against Byram's dimensionless group...

A high-density restriction fragment length polymorphism (RFLP) linkage map is being constructed for loblolly pine (Pinus taeda L.). Loblolly pine cDNA and genomic DNA clones were used as probes in hybridizations to genomic DNAs prepared from grandparents, parents, and progeny of a three-generation outbred pedigree. Approximately 200 probes were evaluated for their ability to detect polymorphic loci between DNAs prepared from the two parent trees, 20-1010 and 11-1060, and cut with four different restriction enzymes: BamHI, DraI, EcoRI, and HindIII. More than half of the probes detecting...

The forecast skill of theNational Meteorological Center's medium range forecast (MRF) numerical forecasts of fire weather variables is assessed for the period June 1,1988 to May 31,1990. Near-surface virtual temperature, relative humidity, wind speed and a derived fire weather index (FWI) are forecast well by the MRF model. However, forecast relative humidity has a wet bias during the winter and a slight dry bias during the summer, which has noticeable impact on forecasts of the derived fire weather index. The FWI forecasts are also strongly affected by near-surface wind forecast errors....

In this chapter we describe the results of airborne studies of smokes from 17 biomass fuel fires, including 14 prescribed fires and 3 wildfires, burned primarily in the temperate zone of North America between 34° and 49°N latitude. The prescribed fires were in forested lands and logging debris and varied in areas burned from 10 to 700 hectares (ha) (over a few hours). One of the wildfires ultimately consumed 20,000 ha and burned over a period of weeks. The larger fires produced towering columns of smoke and capping water clouds. As an indication of scale, the prescribed fires were visible...

Canyon live oak (Quercus chrysolepis Liebm.) showed sprouting patterns on root and trunk zones foUowing forest thinning. Root sprouting was heaviest on north and east (downhill) sides of residual trees; bole sprouts were concentrated on the south and west (uphill). Root and bole sprouting appeared to be responding to different stimuli, or responding differently to the same kind of stimulus. Thinning affected sprout growth, but not sprout numbers. Sprouting responses were at the tree level rather than the thinning treatment leveL Unexpected sprouting occurred in uncut control plots. Light,...