以林分为空间单元,动态评估小班尺度潜在森林火灾风险对于火灾预防管理实践具有重要作用。研究以云南临沧市临翔区多年采脂思茅松林分为对象,采集多年未采脂、采脂条件下的林分因子样本,以火源可及性、死可燃物载量、林分易燃性,以及坡度、坡向、地表湿润度为评估变量,构建小班尺度上的森林火险评估模型,分别评估林分在全国火险等级模型下的基础火险值(BHX)、未采脂条件下的静态火险值(SHX)及采脂条件下动态火险值(DHX)。在地理信息系统(GIS)支持下,利用地图模拟表达采脂活动引起林分可燃物载量和易燃性、火源密度等增加下的火险动态变化格局,并分析林分森林火险等级大幅变化原因。研究结果表明:研究区所有林分具有一致的基础森林火险值(BHX),危险性大;林分可燃物条件差异造成的未采脂林分静态火险值差异较大,大部分小班处于高火险等级;林分因采脂经营活动使各小班火险值呈现不同程度的增加,林分火险等级主要集中在极高火险,火险上升比率大于25%的林分面积超过60%;过度、非规范的采脂经营活动是林分火险等级增加的主要原因。林分是森林经营活动的基本单位,火险评估精细化至不同经营水平下的林分小班尺度,研究对基层林火管理及其它经营措施下火险动态评估具有一定的参考及借鉴价值。

Dynamic assessment of potential fire risk in subcompartment scale of forest stand plays an important role in the application of fire prevention and management practice.Fire risk of tapping and no tapping forest stand of Pinus kesiya var. langbianensis in Lincang city was conducted with fire accessibility,dead fuel load,stand flammability,and surface moisture gradient,aspect based on national rating system BHX,static fire risk SHX and dynamic fire risk DHX respectively.With the support of geographic information system (GIS),the dynamic change pattern of fire risk caused by the increase of fuel load and flammability and the density of fire ignition was mapped,and the reasons for the drastic change of forest fire risk level were discussed.The results show that all forest stand have the consistent values of high fire rating BHX.When accounting the variation of forest fuel condition,the static fire risk of no tapping stand is quite different,mostly at high fire risk.While tapping activities make forest stand fire risk increase in different degree,forest fire danger rating is mainly concentrated in severely high as fire risk rise ratio greater than 25% takes more than 60% forest stand.Excessively and non-standard tapping is the key point of forest fire risk increased.Forest stand is the basic unit of forest management activities,and the fire risk assessment is refined to the small scale of forest stand under different management levels,so the study has certain reference value for fire risk assessment under basic forest fire management and other measurement.