Abstract
Objective Prescribed burning is the most widely used and effective management measure for forest fuels. This study aims to reveal the behavior characteristics of prescribed burning in Pinus yunnanensis forest, so as to effectively clean up the forest land combustibles, reduce the possibility of forest fire, and realize the goal that forest fire management should focus on prevention. Method Downhill fire technology was employed as prescribed burning in P. yunnanensis forest. In the early stage of the fire prevention period, field investigation was conducted in the continuous distribution area of P. yunnanensis in Zhaobi Hill, Xinping County in central Yunnan Province, including sample plot setting and prescribed burning test to investigate the characteristics of fuels and record dynamic changes of fire behavior during the burning process, such as fire spreading rate, fireline intensity, flame temperature and height. Result In the early stage of fire prevention, the moisture content of surface fuels in the forest was 11.99%−12.06%, which was dry and flammable. The burning test showed that the fire spreading speed was 0.14−0.29 m·min−1, the fireline intensity was 147−332 kW·m−1, the flame temperature was 386−578 ℃, and the maximum flame height was 0.9 m. The parameters of fire behavior differed significantly among different surface fuels (P＜0.05), but they were all low-intensity fires. The average under-branch height of P. yunnanensis forest was more than 7 m, and the vertical continuity of surface fuels was poor, so it was difficult for the understory burning flame to spread to the canopy. The unburned land rate accounted for 5% and the overall burning rate was 59.00%−75.00%, which achieved the expected effect and could effectively control combustibles. Conclusion The burning and fire spreading speed in P. yunnanensis forest is slow, belonging to stable surface fire, with spreading speed less than 4 km·h−1, and the surface combustibles burn thoroughly. Fireline intensity is less than 750 kW·m−1, which is a low-intensity fire and manually controllable. The average burning rate is 63.05% and the burning effect is good, and the load of flammable and combustible materials can be regulated to prevent forest fires. [Ch, 2 fig. 5 tab. 33 ref.]
DownLoad:
