Inflamabilidade de espécies da caatinga para uso em cortinas de segurança no Semiárido Paraibano.

Abstract

Forest fires cause numerous social and environmental impacts in Brazil and worldwide. The origin of forest fires can occur intentionally, accidentally or naturally, consuming the combustible material present in the environment. The implementation of safety curtains prevents the spread of a fire on the property and assists in fighting techniques by the firefighters. Thus, the objective of this research was to evaluate the flammability of Caatinga plants and their efficiency as safety curtains in the prevention of forest fires in the Paraiba semiarid. The following combustible materials were tested: T1Palma, T2Pinus (control), T3Mandacaru, T4Pereiro, T5Catingueira, T6Xiquexique and T7Faveleira. Fuel materials from hardwoods, branches with diameters ≤ 0.7 cm and leaves at 50% proportionality were collected. For cactaceae, the vegetative size was considered. The hardwoods and the control treatment were collected and packed in 60 kg bags, properly identified and dried for 90 days. The cacti were collected and put in shed for 15 days, only to decrease the humidity. The flammability evaluation was performed by burning 2.0 kg in 28 plots with dimensions of 1m2, using four repetitions in randomized blocks. Subsequently, the thickness and volume of the blanket, the material humidity, the frequency and time of ignition, the burning time, the flame height, the propagation velocity, the fire intensity, the combustibility and severity index, the temperature of the combustible material and the soil temperature, released energy, ash content and calorific value were determined. The meteorological conditions presented relatively homogeneous values during the burning in all plots, which average values were 32.82%, 26ºC and 2.99ms1, North, for relative humidity, temperature and wind speed, respectively. The cactaceae (Opuntia sp, Cereus jamacaru, Pilosocereus gounellei) presented longer ignition times and shorter combustion times, being burned only the thorns. The faveleira (Cnidoscolus quercifolius) did not differ from the cactaceae in terms of combustion time, which presented lower combustibility and fire severity indexes. The Pereiro (Aspidosperma pyrifolium) and the Catingueira (Poincianella pyramidalis) presented modern severity index, due to the high calorific value of the wood. The Pereiro showed higher temperature and intensity of fire. Cactaceae and faveleira showed lower values of calorific value, confirming and indicating zero flammability in cactaceae and low flammability of the faveleira, being recommended for use as safety curtains. The Pereiro and catingueira showed differences in flammability between the constituent parts of the plants, but with high calorific value in the wood, not being recommended as safety curtains. Caatinga species respond differently to the action of fire, especially among the constituent parts of plants. The combustibility and severity indices methodology are efficient in the evaluation of fire behavior.