Flammability of forest combustible material when exposed to the heat fow

In recent years, the number of forest fires has significantly increased in a number of countries of the world, often acquiring catastrophic scales, which is largely caused by global warming. In the cur- rent situation, adaptation of fire protection measures to the conditions of prolonged drought and increased fire hazard of forest combustible material is required. One of the main factors affecting the occurrence and spread of forest fires is the ability of the ground cover to ignite and maintain the combustion process when exposed to an ignition source. Open flames, sparks, hot objects, ther- mal radiation can serve as sources for initiating combustion. Based on the data on the thermal re- sistance of vegetation, the probability of occurrence and conditions for the development of fires are predicted, methods are being developed to increase the fire resistance of natural ecosystems and limit the development of combustion. A significant place in the issues of forest fire prevention is given to the creation of a system of fire barriers that limit the spread of fires. The width of the obstacle should ensure that the level of thermal impact on the ground material is below the critical value. In this re- gard, the study of the flammability of forest combustible material is extremely relevant. In the course of the studies, it was found that the critical (minimum) value of the heat load required to ignite the main conductors of ground combustion in the form of moss, needle litter, small branch- es, foliage and bark is about 10 % humidity, which meets the conditions of a fire hazard period, is 20 kW/m2 . With an increase in the moisture content of the ground cover up to 30 %, the ignition of . forest combustible material, depending on its type, is observed at a heat load level of 35–40 kW/m2.