We modeled tree mortality occurring two years following wildfire in Pinus ponderosa forests using data from 1275 trees in 25 stands burned during the 1987 Stanislaus Complex fires. We used logistic regression analysis to develop models relating the probability of wildfire-induced mortality with tree size and fire severity for Pinus ponderosa, Calocedrus decurrens, Quercus chrysolepis, and Q. kelloggii. One set of models predicts mortality probability as a function of DBH and height of stem-bark char, a second set of models uses relative char height (height of stem-bark char as a proportion of tree height) as the predictor. Probability of mortality increased with increasing height of stem-bark char and decreased with increasing tree DBH and height. Analysis of receiver operating characteristic (ROC) curves indicated that both sets of models perform well for all species, with 83 to 96 percent concordance between predicted probabilities and observed outcomes. The models can be used to predict die probability of post-wildfire mortality of four tree species common in Pinus ponderosa forests in the central Sierra Nevada of California.

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This report characterizes smoke emissions from small-scale prescribed burns in southern California chaparral. In situ measurements of smoke emissions were made from 12 fires. Three replicate tests were performed in each of four distinct fuel and fire treatments common to vegetation management operations: a young and rigorous chamise-dominated stand; an old and decadent chamise-dominated stand; an old chamise-dominated stand after crushing; and a stand consisting mainly of old ceanothus. Emission factors for total particulate matter, particulate matter 10 micrograms in size and less, particulate matter 2.5 micrograms in size and less, carbon monoxide (CO), carbon dioxide (CO2), methane, and nonmethane hydrocarbons have been developed from the tests. In addition, combustion efficiency and the rates of fuel consumption and heat release were derived from real time measurements of CO, CO2, temperature, and vertical mass flux. The highest combustion efficiencies observed for the flaming phase were from tests at the crushed sites, where most flaming phase emission factors were lower than for the other areas. These results suggested positive management implications for crushing. Emission factors from previous tests in untreated (standing) chaparral are combined with the present data, and the average values from the combined tests are provided for general use in describing smoke emissions from standing chaparral in southern California.Keywords: Emission factor, smoke emissions, chaparral, prescribed burning, smoke management. SummaryEmission factors for total particulate matter (PM), particulate matter 10 pg in size and less (PM10), particulate matter 2.5 IJg in size and less (PM2.5), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and nonmethane hydrocarbons (NMHC) have been developed from measurements of smoke emissions from 12 prescribed burns in southern California chaparral. Three replicate tests were performed in each of four distinct fuel and fire regimes to represent a range of chaparral fuel types and management treatments: a young and thrifty chamise-dominated stand; an old and decadent chamise-dominated stand; an old chamise-dominated stand after crushing; and a stand consisting mainly of old ceanothus.Results from the present study also are combined with data from a previous study to form the most complete set of data available for management to use in making decisions on the impacts of prescribed burning on the air resource. The following values are averages from the combined tests and are provided for general use in describing emissions from standing, untreated chaparral. Weighted-average emission factorsPhase PM PM101 PM2.5 CO CO2 In addition, combustion efficiency and the rates of fuel consumption and heat release were derived from real-time measurements of CO, CO2, temperature, and Vertical mass flux. CH4 NMHC Pounds per ton (+ SE)The highest combustion efficiencies observed for the flaming phase were from the Newhall crushed tests, where flaming phase emission factors for CO, PM, CH4, and NMH...