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Abstract
Introduction
Fire is one of the most dangerous ecological factors in Ukrainian forests resulting in catastrophic consequences. The study of the conditions of the forest debris combustion and burning is important for solving the problem of preventing forest fires and also for using effective fire-fighting methods and means. In particular, the pine forests of Ukrainian Polissya have the root system placed close to the earth surface, and it is the litter to be the most important object of the primary burning.
Materials and Methods
The object of the study was combustion temperature of forest litter from pine plantations of State Enterprise “Ostkivske Forest Economy” of Rivne Regional Department of Forestry and Hunting. In a laboratory, we studied monoliths of litter from different trophotopes (infertile (A) and fairly infertile (B) pine site types) and hygrotopes (dry and very dry). The temperature was measured according to the litter depth using thermocouple instrument. We studied the dynamics of change of litter monolith layers temperature while the flame front (smoldering front) goes through them.
Results and Conclusions
Various trophic monoliths showed a difference in combustion temperature dynamics. In particular, the combustion modes of monoliths from fairly infertile pine site (trophotope B) are characterized by the higher temperature (by 50–100°С) than monoliths from infertile pine site (trophotope A). At the same time, the speed of combustion front expansion of trophotope B monoliths is lower, and the reason of it is the higher density of the combustible material. There is a difference in the monoliths combustion modes in dry and very dry conditions. For dry infertile pine site type litter monoliths, the maximum temperature varies in the range of 131–295°С from lower to upper layers. The lowest temperature was measured in the lowest H layer and the medium F layer of the litter. The litter combustion temperature of very dry monoliths increases significantly. The minimum combustion temperature was recorded at the depths more than 3 cm in the H layer (333–347°С), and maximum one was recorded in the F layer (525–655°С). The forest litter burning speed has a tendency of reducing to the depths of the layer. The exception is the monolith surface refreshed by its convection currents while burning with heat evolution.
The effect of the wind on changing combustion parameters was qualitatively evaluated. The presence of wind during the experiment causes the oxygen enrichment in the deep litter layers and also more intense burning and elevation of the temperature in these layers.
The methodology used is promising, as it can be used to simulate not only litter-humus and steppe fires in the laboratory.