Factor contribution to fire occurrence, size, and burn probability in a subtropical coniferous forest in East China

The contribution of factors including fuel type, fire-weather conditions, topography and human activity to fire regime attributes (e.g. fire occurrence, size distribution and severity) has been intensively discussed. The relative importance of those factors in explaining the burn probability (BP), which is critical in terms of fire risk management, has been insufficiently addressed. Focusing on a subtropical coniferous forest with strong human disturbance in East China, our main objective was to evaluate and compare the relative importance of fuel composition, topography, and human activity for fire occurrence, size and BP. Local BP distribution was derived with stochastic fire simulation approach using detailed historical fire data (1990–2010) and forest-resource survey results, based on which our factor contribution analysis was carried out. Our results indicated that fuel composition had the greatest relative importance in explaining fire occurrence and size, but human activity explained most of the variance in BP. This implies that the influence of human activity is amplified through the process of overlapping repeated ignition and spreading events. This result emphasizes the status of strong human disturbance in local fire processes. It further confirms the need for a holistic perspective on factor contribution to fire likelihood, rather than focusing on individual fire regime attributes, for the purpose of fire risk management.

包括燃料类型、火灾天气条件、地形与人类活动在内的各类因子对火灾态势（fire regime）属性（例如火灾发生、规模分布与火灾烈度）的贡献已得到广泛讨论，但上述因子在解释燃烧概率（BP）——这一火灾风险管理中的关键指标——方面的相对重要性却尚未得到充分研究。本研究聚焦中国华东地区受强烈人类干扰的亚热带针叶林，核心目标为评估并对比燃料组成、地形与人类活动对火灾发生、火灾规模以及燃烧概率的相对重要性。研究基于1990–2010年的详细历史火灾数据与森林资源清查结果，采用随机火灾模拟方法推导得到局地燃烧概率分布，并据此开展因子贡献分析。研究结果表明，燃料组成对火灾发生与火灾规模的解释度最高，而人类活动则是燃烧概率变异的最主要解释因子。这意味着人类活动的影响会通过重复点火与火灾蔓延的叠加过程被放大，凸显了局地火灾过程中强烈人类干扰的作用地位。本研究进一步证实，在火灾风险管理工作中，需从整体视角分析各类因子对火灾发生可能性的贡献，而非仅聚焦于单一火灾态势属性。