Fire Behavior And Fighting Measures Of Major Forest Types In The Mountainous Area,Beijing

In this paper,the major forest types in mountainous area of Beijing of Pinus tabulaeformis forest,Platycladus orientalis forest,Quercus variabilis forest and Robinia pseudoacacia forest were studied.The typical forests were selected for field surveys,combined with indoor experiment,model prediction et al.By studying the distribution characteristics of surface fuel loadings and canopy fuel loadings in different forest types,the Behaveplus software was used to investigate the potential fire behaviors of different forest types under different combustion conditions.And the firefighting measures under different burning conditions were presented.Under the premise of ensuring the safety of personnel and equipment,the theoretical basis is provided for minimizing the harm brought by forest fires.The results are as follows:(1)There were significant difference in fuel loading of major different forest types.The Pinus tabulaeformis forest had the highest surface fuel loading,at 13.054 t/hm2.The other surface fuel loadings was expressed as follows:Robinia pseudoacacia forest,Platycladus orientalis forest,Quercus variabilis forest;The Platycladus orientalis forest had the highest crown fuel loading,at 24.399 t/hm2,along with the high vertical continuity,the other crown fuel loadings was expressed as follows:Pinus tabulaeformis forest,Robinia pseudoacacia forest,Quercus variabilis forest.(2)Based on fuel moisture content and the wind speed,forest burning level were divided into high,medium and low level.In the low burning condition,the four forest types can only form low intensity surface fire and cannot threaten the forest.In the medium burning condition,the Pinus tabulaeformis forest had high speed passive crown fire,and the Platycladus orientalis forest will occur more dangerous active crown fire.The surface fire intensity of Robinia pseudoacacia forest can reach the medium intensity surface fire.In the high burning condition,Pinus tabulaeformis forest and Platycladus orientalis forest can form active crown fire.Although the Robinia pseudoacacia forest had the high intensity surface fires,but because of the low branch height and low canopy fuel loadings could not be transformed by a surface fire to crown fire.(3)The potential fire behavior parameters of different forest types was positively correlated with fuel load,wind speed,slope,and negatively correlated with moisture content.The contribution degree of wind speed is higher than slope.In the absence of wind conditions,low moisture content,high slope,Four kinds of fuel type could only form low intensity surface fire;under the condition of low humidity environment,slope of 0°,15m/s wind speed.The Platycladus orientalis forest fire could have great harm to forest.(4)Under different burning conditions,different forest types took different fighting measures.With the increase of heat release per unit area,the fire became more and more difficult to fight and the range of man controllable fires became smaller.When the surface flame length was more than 3m,the fire will be completely out of control,people and property should be transferred in time.