气候变化背景下大兴安岭林区火险期动态格局与趋势研究

Fire is one of the dominant disturbances in Greater Xing'an Mountains forest , and forest fire is a primary process that influences the vegetation composition and structure of this area. Research indicates that climate change may have short and longer term effects on forest fires, and forest fires may be the response indicator of climate change on forest. Studies of the impacts of climate change and forest fire season for the Greater Xing'an Mountains forest are our most urgent need at present. Forest fires in the Greater Xing'an Mountains forest are most serious in China, and the Greater Xing'an Mountains is also one of the regions which are most sensitive to climate change. Due to the lack of a quantitative method to define the fire season, it is hard to quantitative analysis of the key factors of fire season with the impact of climate change, and the quantitative analysis of fire season is in urgent need to determine the fire season period. This project selects the Greater Xing'an Mountains as the study area, will build the quantitative fire season model based on fire history data, meteorological data and fire weather index, determine the threshold criteria for the fire season period, and study dynamic fire season regime of the Greater Xing'an Mountains for nearly 40 years in the context of the study of climate change. Based on remote sensing, study the humidity and accumulation of typical forest fuel near and between fire season, and analysis flammability of different type of fuel. In addition to studying the impact of past climate change on fire season, this project will also study the dynamic spatiotemporal pattern of fire season based on climate change scenarios and quantitative fire season model, analysis the changes characteristics of the key factors of fire season under future climate change scenarios (2020-2100). This project will change the static management of fire season to dynamic management of fire season under the study of quantitative fire season, and propose fire management methods and strategies to adapt to the climate change of the study area.

大兴安岭林区是中国森林火灾最为严重，对气候变化最敏感的区域之一。受气候变化影响，大兴安岭林区火险期发生明显变化。火险期响应的数量化特征，是反应气候变化对森林火灾影响的关键指标之一，由于缺乏数量化定义火险期的方法，很难对火险期各关键因子进行定量分析，对火险期定量化分析成为一个难题，急需定量化确定火险期的方法。 本项目以大兴安岭林区为研究区域，根据火历史数据、气象数据和火险指数等构建林火发生概率模型和火险期模型，确定火险期的阈值标准。研究气候变化背景下大兴安岭林区过去40年火险期动态响应特征。基于遥感反演和地面分析，研究火险期前后研究区域内典型可燃物燃烧性变化。基于气候变化情景数据和火险期模型,研究不同气候变化情景下未来（2020-2100年）火险期关键因子和可燃物燃烧性时空趋势特征，提出适应于研究区域火险期变化特点的林火管理方法和策略，实现火险期由静态管理向动态管理的转变。

项目围绕气候变化背景下大兴安岭林区火险期动态格局与趋势研究的关键科学问题，系统开展了大兴安岭森林可燃物燃烧性研究、大兴安岭林火发生的时空格局、不同气候变化情景下黑龙江森林火灾发生、季节性和空间变异性研究、大兴安岭火发生概率模型构建、防火期模型构建、气候变化背景下大兴安岭防火期响应特征、不同气候变化情景大兴安岭防火期发生趋势等方面的研究。结果表明：可燃物和火管理对火险具有重要影响，计划烧除是一种有效的可燃物调控方式，能有效减少可燃物载量，降低可燃物高度和厚度，改变可燃物立体结构和连续分布，切断林火发生和蔓延的通道，降低火险。防火期与高火险期首日间隔的天数呈明显缩短的趋势。大兴安岭防火期日数在整体上增加的同时，高火险期日数的增加趋势更大。1987年以后火灾次数明显降低，从2000年开始火灾次数开始有比较大的增加，但这种增加在各个月份是不均衡的，主要由6月份和8月份雷击火次数大量增加引起来的，而尤以8月份增加速率最快。雷击火次数占总火灾次数比例加大。不同情景下防火期终日和高火险期终日均有延后的趋势，其中高火险期延后趋势更加明显。A2情景下，防火期和高火险期比B2情景下延后的速率更大一些。A2、B2气候变化情景下，防火期和高火险期日数均有明显增加的趋势。高火险期日数增加更加明显。在A2气候变化情景下2090s年比2010S年防火期平均日数增加了6天，高火险期平均日数增加了26天。在两种情景下，均是雷击火增加比例最大，在气候变化影响下，雷击火的发生将会日趋严重。人为火发生最危险的区域主要位于大兴安岭的东南部，雷击火发生最危险的区域主要分布于大兴安岭的北部。项目构建了火发生概率模型、防火期模型，同时编制了行业标准、发明专利和软件,研究气候变化情景下未来火险期关键因子和火灾发生危险性时空趋势特征，有一定的使用价值，对实现火险期由静态管理向动态管理的转变有重要意义。