Larissa Alves Secundo White

Evaluation of Forest Fire Danger Indexes for Eucalypt Plantations in Bahia, Brazil

A Forest Fire Danger Index is a valuable tool in forest fire prevention and firefight because it grades fire occurrence possibility on a daily basis. Six Fire Danger Indexes were tested for accuracy based on forest fire occurrence in eucalyptus plantations of the north coast of Bahia, Brazil. They are Angstron, Nesterov, Telicyn Logarithmic Index, Monte Alegre, Rodriguez and Moretti, and Modified Monte Alegre. The results were analyzed using two parameters of the Heidke Skill Score test: Skill Score index and Percentage of Success. The Telicyn Logarithmic Index proved to be the most accurate for the study area.

EMPIRICAL MODELS FOR DESCRIBING FIRE BEHAVIOR IN BRAZILIAN COMMERCIAL EUCALYPT PLANTATIONS

Modeling forest fire behavior is an important task that can be used to assist in fire prevention and suppression operations. However, according to previous studies, the existing common worldwide fire behavior models used do not correctly estimate the fire behavior in Brazilian commercial hybrid eucalypt plantations. Therefore, this study aims to build new empirical models to predict the fire rate of spread, flame length and fuel consumption for such vegetation. To meet these objectives, 105 laboratory experimental burns were done, where the main fuel characteristics and weather variables that influence fire behavior were controlled and/or measured in each experiment. Dependent and independent variables were fitted through multiple regression analysis. The fire rate of spread proposed model is based on the wind speed, fuel bed bulk density and 1-h dead fuel moisture content (r2 = 0.86); the flame length model is based on the fuel bed depth, 1-h dead fuel moisture content and wind speed (r2 = 0.72); the fuel consumption proposed model has the 1-h dead fuel moisture, fuel bed bulk density and 1-h dead dry fuel load as independent variables (r2= 0.80). These models were used to develop a new fire behavior software, the “Eucalyptus Fire Safety System”.

FIRE BEHAVIOR PREDICTING MODELS EFFICIENCY IN BRAZILIAN COMMERCIAL EUCALYPT PLANTATIONS

Knowing how a wildfire will behave is extremely important in order to assist in fire suppression and prevention operations. Since the 1940’s mathematical models to estimate how the fire will behave have been developed worldwide, however, none of them, until now, had their efficiency tested in Brazilian commercial eucalypt plantations nor in other vegetation types in the country. This study aims to verify the accuracy of the Rothermel (1972) fire spread model, the Byram (1959) flame length model, and the fire spread and length equations derived from the McArthur (1962) control burn meters. To meet these objectives, 105 experimental laboratory fires were done and their results compared with the predicted values from the models tested. The Rothermel and Byram models predicted better than McArthur’s, nevertheless, all of them underestimated the fire behavior aspects evaluated and were statistically different from the experimental data.

Characterization of the understory fuel in 'Serra de Itabaiana' National Park - Sergipe State, Brazil

The National Park ‘Serra de Itabaiana’, as well as other conservation units in Brazil, has commonly suffered ecological losses caused by the wildfires. It is essential to comprehend the characteristics of the fuel to a better understanding of a forest fire behavior and how to extinguish it. In order to do so, 108 plots of 1m 2 were delimitated and all of the surface fuel was collected and weighed. The samples were then removed and placed in an oven to determine the moisture content and the dry weight. It was collected, in the study area, a total of 91.38 kg of dry biomass, corresponding to 8.46t/ha. Considering each vegetation type, the Grass Fields had an average of 3.7t/ha of fuel load, the Forests 12.5t/ha and the White Sands 9.18t/ha. The results suggest that the fuel in white sand areas can ignite more easily; there is greater difficulty of fire ignition in forest areas; and short-lived fires in grass fields.

CARACTERIZAÇÃO DO MATERIAL COMBUSTÍVEL SUPERFICIAL NO PARQUE NACIONAL SERRA DE ITABAIANA – SERGIPE, BRASIL

O Parque Nacional Serra de Itabaiana, assim como diversas outras unidades de conservacao no Brasil, comumente sofrem perdas ecologicas em funcao dos incendios que os atingem. Sendo assim, torna-se essencial compreender as caracteristicas do material combustivel para um melhor entendimento do comportamento do fogo e como melhor combate-lo. Para tal, foram demarcadas 108 parcelas de 1 m2 onde todo o material combustivel superficial foi coletado e pesado. Subamostras foram retiradas e colocadas na estufa para determinar o teor de umidade e o peso da materia seca. No total, foram coletados, dentro da area de estudo, 91,38 kg de biomassa seca, correspondente a 8,46 t/ha. Considerando cada fitofisionomia individualmente, os Campos Graminosos apresentaram uma media de 3,7 t/ha de material combustivel, as Matas 12,5 t/ha e as Areias Brancas 9,18 t/ha. Os resultados obtidos sugerem maior facilidade de ignicao do material combustivel nas areas de Areias Brancas; maior dificuldade de ignicao nas areas de Matas; e incendios de curta duracao nas areas de Campos Graminosos.