Data on variables of fire behavior in a study carried out in the Caatinga Biome
Description
The hypothesis is that the fire behavior varies with the type and quantity of combustible material in the different regions of the Caatinga. The objective of this work was (i) to evaluate the fire behavior of material from preserved areas of the Caatinga biome in different geographic regions of the hinterland of the Paraíba and (ii) to determine whether the type and amount of combustible material collected in each preserved area of Caatinga affect the fire intensity and spread. The combustible material was collected in the geographic regions of Cajazeiras, Catolé do Rocha, Itaporanga, Patos, Pombal, Princesa Isabel and Sousa in the hinterland of the Paraíba State, Brazil. The combustible material was collected in seven areas (one per region) of the Caatinga with at least 30 years of preservation with arboreal-shrubby vegetation and herbaceous layer in August 2018. Three plots of 20 x 20 m (400 m²) 200 meters apart from each other were marked per area. The combustible material wascollected with the aid of a template (1.0 m x 1.0 m), thrown randomly three times per plot totaling nine samples per area. The vegetation, up to 1.8 m high inside the template, was removed with a machete and pruning shears to facilitate the removal of superficial combustible material. The fire behavior variables observed during the burning of the material in each plot were: 1- propagation speed (PS); 2- burning duration (BD); 3- flame height (FH). These observations allowed to obtaining the following parameters: 1- fire intensity (I); 2- heat released per unit of area. The fire behavior response variables differed between regions. The propagation speed was higher in the material from the Cajazeiras region (0.0168 m s-1) than in the others and with the lowest value in Catolé do Rocha (0.0941 m s-1). The burning duration of the combustible material was longer for Catolé do Rocha (928.6 s) and shorter for Cajazeiras (203.0 s) and Princesa Isabel (271.3 s) materials. The flame height was greater in the combustible material from the Pombal (1.37 m) region, almost triple that of Catolé do Rocha, with the lowest value (0.53 m). An inverse pattern was observed for fire intensity, with a higher value in the material from the Catolé do Rocha region (9687.58 kJ m-1 s-2) than from the Cajazeiras, Princesa Isabel and Patos minor regions, 427.65 kJ m-1 s-1, 490.54 kJ m-1 s-1 and 667.97 kJ m-1 s-1 respectively. The fire behavior in materials from the Caatinga preserved areas of the hinterland of the Paraíba state, Brazil varied with the types and quantities of combustible material, with emphasis on the greater accumulation of fire in the Catolé do Rocha, Itaporanga and Pombal regions. The continuous deposition and the low moisture content of the combustible material on the forest floor prove that the areas evaluated are susceptible to high intensity fires.