宁波市森林火灾时空分布特征研究

Research on Temporal and Spatial Distribution Characteristics of Forest Fires in Ningbo

本文对浙江省宁波市1996—2021年574起森林火灾的年、月、日变化规律及和地域分布、地形地貌、林分类型、林分结构特征等空间分布特征进行了统计分析,构建了林火空间分布特征图。研究结果表明,1996—2021年宁波森林火灾出现了由低发到高发再降低的变化特征,其中2003—2005年达到最高峰,近年出现了持续低发的良好态势;一年之中,11月至次年4月是森林火灾发生较为集中的月份,其中以3月和4月为高发期;一天之中上午10时至下午16时是引发森林火灾最集中的时间。森林火灾的发生与区域森林面积大小、野外非法用火、路网分布、海拔高度、坡度、坡向、林种、林龄、林分郁闭度等空间因子呈现出关联性,区域森林面积大、野外非法用火多、与路网距离近、低丘缓坡、阳坡、林缘、松林、中幼林、林分郁闭度为0.2~0.3的林分,林火发生的风险较高。通过核密度分析方法生成了宁波市历史森林火灾发生情况热力图,并在空间上提出了县域内、县域间、市域间等3类高风险区域。

This paper made a statistical analysis of the annual,monthly,and daily variation laws of 574 forest fires in Ningbo from 1996 to 2021,as well as spatial distribution characteristics such as geographical distribution,topography,stand types,and stand structure characteristics.The results showed that:from 1996 to 2021,Ningbo forest fires showed a change from low incidence to high incidence and then decreased,which reached the highest peak between 2003 and 2005,and showed a good trend of continuous low incidence in recent years.During the year,from November to next April,forest fires are more concentrated,especially in March and April.There has been a significant correlation in the occurrence of forest fires with spatial factors such as regional forest area,illegal using fire in the wild,distance to the road network,altitude,slope,slope aspect,forest species,forest age,and stand canopy closure.There can be a higher risk of forest fires in regions with larger forest areas,more illegal use of fire in the wild,closer distance to the road network,lower hills and gentler slopes,sunnier slopes,forest margins,pine forests,young and middle-aged forests,and forest stands with a canopy density of 0.2~0.3.The thermal map of historical forest fire in Ningbo generated by Kernel density analysis method indicated three types of high-risk areas which were within the district,between districts,and between cities.