基于可燃物特征的塞罕坝林场人工林小班森林火险区划

Forest Fire Risk Zoning of Artificial Forest Subcompartment in Saihanba Forest Farm Based on Fuel Characteristics

【目的】以塞罕坝机械林场为例,建立一种基于可燃物特征的森林火险区划方法,为林场尺度火险区划提供借鉴。【方法】选取15个火险影响因子,运用层次分析法(AHP)、专家打分法和判断矩阵法获得小班尺度引燃危险、火强度危险和综合火险的因子权重,以小班调查数据和可燃物理化性质测定数据为基础,计算每个小班的引燃危险指数、火强度危险指数和综合火险指数;采用聚类分析法和ArcGIS技术,得到林场内引燃危险、火强度危险和综合火险的等级区划图,分析林场区域的火灾发生危险性。【结果】1)在塞罕坝机械林场,引燃危险等级极高(Ⅴ_(Y))区域面积占林场总面积的9.21%,主要零散分布于林场西部、南部和中部;高(Ⅳ_(Y))和较高等级(Ⅲ_(Y))分布区域较广,全区均有分布,较高以上等级(Ⅲ_(Y)、Ⅳ_(Y)、Ⅴ_(Y))面积占比67.95%。2)火强度危险极高等级(Ⅴ_(Q))面积最大,占林场总面积的46.42%,其次是高等级(Ⅳ_(Q)),面积占比26.38%,二者面积之和占比72.8%,集中在林场南部和西部;较高等级(Ⅲ_(Q))面积占比7.95%,主要分布在东部。3)综合火险等级高(Ⅳ_(Z))和较高(Ⅲ_(Z))面积占比大,分别为29.07%和28.12%;极高等级(Ⅴ_(Z))面积占比也达19.13%;较高以上等级(Ⅲ_(Z)、Ⅳ_(Z)、Ⅴ_(Z))区域面积总占比为76.32%,主要分布于林场西部、南部和中部。【结论】基于层次分析法、聚类分析法和ArcGIS技术的火险区划方法,能在小班尺度很好地进行森林火险分类,得到引燃危险、火强度危险和综合火险区划,对林场等级的可燃物管理有参考价值。塞罕坝机械林场综合火险等级很高,特别是西部、南部和中部;林场火强度危险等级极高(Ⅴ_(Q))和高(Ⅳ_(Q))的区域面积很大,一旦着火极易引发高强度森林火灾。引燃危险等级高和火强度危险等级高的区域并不完全重合,需在引燃危险等级高的区域内加强火源管理和易燃可燃物管理,降低火发生概率,建议在火强度危险等级高的区域和引燃危险等级高的区域之间规划隔离带,以有效阻滞可能发生的林火向火强度危险等级高的区域快速蔓延,防控大火巨灾发生。

【Objective】Using the Saihanba Mechanized Forest Farm as a case study,a forest fire risk zoning method based on forest combustible characteristics was established,providing a reference for fire risk zoning at the forest farm scale.【Method】15fire risk influencing factors were selected,The analytic hierarchy process(AHP),expert scoring,and judgment matrix methods were used to derive the factor weights for ignition danger,fire intensity danger,and comprehensive fire risk at the plot scale.Based on plot survey data and determination of the combustible physical and chemical properties,the ignition danger index,fire intensity danger index,and comprehensive fire risk index for each plot were calculated.Cluster analysis and ArcGIS technology were used to generate zoning maps for ignition danger,fire intensity danger,and comprehensive fire risk within the forest farm,and to analyze the fire occurrence risk within the forest farm area.【Result】1)In the Saihanba Mechanized Forest Farm,the area of the extremely high ignition danger(V_(Y))level accounts for 9.21%of the total area of the forest farm,mainly scattered in the west,south,and central parts of the farm;the high(Ⅳ_(Y))and moderately high(Ⅲ_(Y))levels have a wider distribution,with presence throughout the study area;The combined area of the higher than high levels(Ⅲ_(Y),Ⅳ_(Y),V_(Y))accounts for 67.95%.2)The area of the extremely high fire intensity danger(V_(Q))level is the largest,accounting for 46.42%of the total area of the forest farm,followed by the high level(Ⅳ_(Q)),which accounts for 26.38%;the sum of the two levels is 72.8%,mainly concentrated in the south and west of the forest farm;the higher level(Ⅲ_(Q))accounts for 7.95%of the farm area,mainly distributed in the east.3)The area of the high(Ⅳ_(Z))and moderately high(Ⅲ_(Z))comprehensive fire risk levels is large,accounting for 29.07%and 28.12%,respectively;the extremely high level(V_(Z))accounts for 19.13%;the moderately high and higher levels(Ⅲ_(Z),Ⅳ_(Z),and V_(Z))collectively account for76.32%of the total area,mainly distributed in the west,south,and central parts of the forest farm.【Conclusion】The fire risk zoning method established in this study,based on the AHP,cluster analysis,and ArcGIS technology,can effectively classify forest fire risk at the plot scale,generating zoning for ignition danger,fire intensity danger,and comprehensive fire risk,and is a valuable reference for the management of combustible materials at the forest farm level.The comprehensive fire risk level in the Saihanba Mechanized Forest Farm is very high,especially in the west,south,and central parts of the forest farm;the area of the extremely high(V_(Q))and high(Ⅳ_(Q))fire intensity danger levels is extensive,and once ignited,it is highly likely to cause high-intensity forest fires.The areas with high ignition danger and high fire intensity danger do not completely overlap.It is essential to strengthen fire source management and the management of flammable and combustible materials in areas with high ignition danger to reduce the probability of fire occurrence.In addition,the implementation of isolation belts located between areas with high fire intensity danger and high ignition danger is recommended to effectively prevent the rapid spread of potential fires to areas with high fire intensity danger,and to control the occurrence of large-scale disasters.