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

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.