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    基于小班尺度的北京市密云区森林火灾危险性评价

    Hazard assessment of forest fire in Miyun District of Beijing based on the subcompartment scale

    • 摘要:
      目的 森林火灾危险性评价是实现科学林火管理工作的重要前提和基础,基于小班尺度开展森林火灾危险性评价及其空间特征分析,可为林火精细化管理提供依据。
      方法 以密云区为研究对象,基于2019年森林资源二类调查小班数据、森林可燃物数据、气象数据、重要火源点等数据,构建密云区森林火灾危险性评价体系,应用层次分析法和熵权法相结合的主客观赋权法确定评价体系中各指标权重,根据评价体系中最终权重采用加权综合评价法计算各小班的危险性指数,依据自然断点分级法划分为高、中高、中低、低4个等级;采用全域和局域莫兰指数判断各小班之间的空间自相关性和聚集分布特征。
      结果 (1)基于小班尺度综合4类因子构建体系,权重分布比例合理,可较好地开展火灾危险性评价;(2)研究区内高等级、中高等级、中低等级、低等级危险性的小班面积占比分别为12.75%,19.01%,41.70%,26.54%。其中,高等级危险性小班以灌木林、侧柏林、油松林为主,小班面积占比分别为38.40%、25.76%、24.13%;(3)高等级危险性小班分布在研究区范围的东部以及中南部区域,从乡镇尺度分析,呈片状分布于巨各庄镇、高岭镇和新城子镇;(4)小班危险性的全域莫兰指数为0.241 3(大于0),说明密云区各小班存在一定的正相关性,即小班呈现出聚集分布的特征,采用局域莫兰指数分析发现火灾危险性等级为高−高聚集型小班的面积达34 637.77 hm²,占密云区面积的15.56%。
      结论 (1)构建的森林火灾危险性评价体系中,野外火源所占权重最大,是影响森林火灾危险性的主要因素;(2)高等级危险性小班区域灌木林占比较高,且聚集分布特征明显,根据权重结果,建议增强对野外火源和重点人群的监督和管理;另一方面,制定可燃物清理的标准和要求,定期在农林交错地区和火源点周围进行可燃物清理作业。

       

      Abstract:
      Objective Forest fire hazard assessment is an important prerequisite and foundation for achieving scientific forest fire management. Conducting forest fire hazard assessment and spatial feature analysis on subcompartment scale can provide a basis for refined forest fire management.
      Method Taking the subcompartment of Miyun District as the research object, based on the data of forest resource secondary survey subcompartment, forest fuel data, meteorological data, important fire source points, etc. in 2019, a forest fire hazard assessment system was constructed. We used the subjective and objective weighting methods of combining analytic hierarchy process and entropy weight method to determine the weights of various indicators in the evaluation system. Based on the natural breakpoint classification method, four levels were divided as high, medium-high, medium-low, and low. Global and local Moran indices were used to determine the spatial autocorrelation and clustering distribution characteristics between subcompartments.
      Result (1) Research was based on the construction of a comprehensive system of 4 types of factors at the subcompartment, with reasonable weight distribution ratios, which can effectively carry out fire hazard assessment. (2) The proportions of hazard subcompartment areas with high level, medium-high level, medium-low level, and low level were 12.75%, 19.01%, 41.70%, and 26.54%, respectively. Among them, the high-level hazard subcompartment was mainly composed of shrubbery, Platycladus orientalis forest, and Pinus tabuliformis forest, with subcompartment areas accounting for 38.40%, 25.76%, and 24.13%, respectively. (3) High level hazardous small classes were distributed in the eastern and central southern regions of the research area. From a township level analysis, they were distributed in a patchy pattern in Jugezhuang Town, Gaoling Town, and Xinchengzi Town. (4) The global Moran index of the hazard of subcompartments was 0.2413 (> 0), indicating that there was a certain positive correlation among the subcompartments in Miyun District and the subcompartments exhibited clustering distribution characteristics. Using the local Moran index analysis, it was found that the area of the subcompartments with a high to high clustering was 346 37.77 ha, accounting for 15.56% of the area of Miyun District.
      Conclusion (1) In the forest fire hazard assessment system constructed in this article, the weight of outdoor fire sources is the largest, which is the main factor affecting the forest fire hazard. (2) The proportion of shrub forests in high-risk small class areas is relatively high, and the clustering distribution characteristics are obvious. Based on the weight results, it is recommended to strengthen the supervision and management of outdoor fire sources and key populations; on the other hand, establishing standards and requirements for combustible material cleaning, and combustible material cleaning operations were regularly carried out in areas where agriculture and forestry intersect and around fire sources.

       

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