LUZ, M. N.; http://lattes.cnpq.br/8959201543385705; LUZ, Mellina Nicácio da.
Resumo:
The use of fire in a controlled way in vegetation can provide positive results, however, it can
spread in an uncontrolled way in the area, causing damage in the most diverse aspects. Thus,
the objective of this research was to evaluate the characteristics of species found in the
immediate geographical region of Patos when submitted to the action of fire. Twig, branches
and leaf samples were collected from ten species that occur in the immediate region of Patos.
Each treatment material was packed in 60kg nylon bags and were properly identified. The
design used was entirely randomized, in which 10 treatments were tested with 3 repetitions,
consisting of combustible material from the following species: angico (Anadenanthera
colubrina), capim panasco (Aristida adscensionis), catingueira (Cenostigma bracteosum),
craibeira (Tabebuia aurea), faveleira (Cnidoscolus quercifolius), juazeiro (Sarcomphalus
joazeiro), jurema preta (Mimosa tenuiflora), marmeleiro (Croton sonderianus), oiticica
(Microdesmia rigida) and pereiro (Aspidosperma pyrifolium). In fire behavior, parameters such
as material and soil temperature before and after burning, flame height and temperature, ignition
time and frequency, propagation speed, burning duration, and fire intensity were evaluated. In
addition, the ash content was also evaluated. The meteorological conditions varied little, with
averages of 33.47ºC, 52.33% and 0.93 m s-1 for temperature, relative humidity and wind speed,
respectively. The temperature of the material did not differ statistically between treatments;
however, there were statistical differences after burning, especially for the craibeira,
marmeleiro and oiticica. Significant differences were found for the height of the flames, where
the lowest heights were observed in the faveleira, catingueira, angico and jurema preta.
However, for flame temperature, the treatments were statistically similar. Some species had
some difficulty in igniting, such as the pereiro and, especially the faveleira, the flames ceased
quickly. In the speed of propagation, we identified statistical superiority of capim panasco with
0.0335 m s-1, being the only species classified as medium speed and the jurema preta obtained
the lowest rate, with 0.0025 m s-1, classified as slow. Besides these, the velocity of the faveleira
was null, since the fire was extinguished in a short time. The maximum burning duration was
found in the angico plots, with an average of 24 min in the combustion process, being
statistically different from the faveleira plots, which accounted for about 3 min in combustion.
The capim panasco stood out in fire intensity, in which 402.43 kcal m-1s
-1 were responsible for
the classification in very high severity. In contrast, species such as catingueira and jurema preta
were rated low and moderately low, respectively. The jurema preta obtained the lowest wood
ash content, which is favorable for its energy potential. When affected by fire, the species found
in the caatinga have different responses. C. quercifolius is a species of low flammability, in
view of the difficulty in igniting and maintaining combustion. Places with the abundant
presence of A. adscensionis should be monitored frequently for the risk of occurrence of fires,
especially in times with atmospheric conditions favorable to the occurrence of fire.