多气候情景下大兴安岭森林燃烧性评估

Assessment of Burn Probability Assessment in Daxing'anling under Multi-Climatic Scenarios

【目的】利用燃烧概率模型BURN-P3描述未来不同气候情景下大兴安岭地区的林火动态变化,提高对气候变化影响的认知,为开展林火管理适应技术提供科学依据。【方法】基于RCP2.6、RCP4.5、RCP6.0和RCP8.5气候情景的气候模式数据,利用历史地面观测气象数据对气候模式数据的气温和降水量分别进行了校正。根据火险天气指数系统(FWI)分别计算研究区各格点的森林火险天气指数,结合研究区可燃物类型、火发生和地形等数据,利用BURN-P3软件逐日模拟1971—2050年黑龙江大兴安岭地区的火发生与蔓延状况,分析不同气候情景下的森林燃烧概率和火行为变化。【结果】1991—2010年研究区模拟平均燃烧概率为0.010 8,过火区(除2003年)燃烧概率为0.011 3,火发生位置的平均燃烧概率为0.012 45,t检验表明差异显著。2003年研究区平均燃烧概率为0.014 2,比1991—2010年平均值高31.5%。通过对过去时段的模拟结果与实际过火区比较分析,表明BURN-P3模型能较好地模拟大兴安岭地区的林火动态。与基准时段相比,2021—2050年RCP2.6、RCP4.5、RCP6.0和RCP8.5气候情景下燃烧概率平均增幅分别为-6.21%,7.71%,7.80%和19.48%,燃烧概率增幅较大的区域主要分布在中南部;火烧强度将分别增加-13.0%,4.4%,1.5%和8.0%;树冠火比例分别增加-12.7%,4.2%,5.0%和4.7%,中部和西部树冠火增多显著。【结论】BURN-P3模型可用于模拟大兴安岭的林火动态,模拟结果可反映森林燃烧概率状况。与基准时段相比,2021—2050时段RCP2.6气候情景下平均燃烧概率有所降低,RCP4.5、RCP6.0和RCP8.5气候情景下燃烧概率将增加,火烧强度、蔓延速度和树冠火比率都呈现小幅增加。中南部的火活动明显增强,不同气候情景之间有所差异。

【Objective】The assessment for forest combustion is a base of fire management. Simulation of the fire regime under different climate change scenarios with the burn probability model is an important way to understand the effects of climate change on fire activities. In this study,burning probability model（ BURN-P3） was used to simulate the fire occurrence and spread on the landscape scale. The fire regime changes in Daxing＇anling under four climate scenarios were described quantitatively based on the simulations with the burn probability model,which would facilitate understandings of the impacts of climate change and provide the scientific basis for fire management. 【Method】The climate data simulated from the climate model for climate scenarios RCP2. 6,RCP4. 5,RCP6. 0,and RCP8. 5 were calibrated by using historical ground observations for temperature and precipitation. This paper simulated daily fire occurrence and spread in the Daxing＇anling in 1971- 2050 for four climate scenarios with the climate model data,fire weather index system and combustion probability model（ BURN-P3）. It was analyzed for the burn probability and fire behavior with the data of fuel type,fire occurence and terrain in the study area. 【Result 】The average burn probability for the whole study area in1991- 2010（ except 2003） was 0. 010 8,and the average for fire scars 0. 011 3. The average burn probability for thelocations of fire occurrence was 0. 012 45,which showed significant difference with the average for whole study area by ttest. In 2003,the average burn probability for the study area was 0. 014 2,which 31. 5% higher than that of 1991-2010. BURN-P3 model can be used in the study area for simulating fire regimes through comparative analysis for the simulation results and actually burned areas in history. Compared with the baseline period（ 1971- 2000）,the average combustion probability in 2021- 2050 under climate scenarios RCP2. 6,RCP4. 5,RCP6. 0,and RCP8. 5 would increase- 6. 21%,7. 71%,7. 80%,and 19. 48%,respectively. The increased areas were mainly distributed in the central and southern parts. Fire intensity would increase- 13. 0%,4. 4%,1. 5%,and 8. 0% respectively. Meanwhile,the crown fraction burned would have an increase by- 12. 7%,4. 2%,5. 0%,and 4. 7%,respectively. The central and western parts would have a significant increase.【Conclusion】The simulation results of BURN-P3 can reflect the status of forest burn probability in Daxing＇anling. Compared to the baseline period（ 1971- 2000）,the average combustion probability in 2021- 2050 under climate scenario RCP 2. 6 would decrease,but it would increase under RCP4. 5,RCP6. 0 and RCP8. 5. The average fire intensity,rate of spread and combustion probability would show a slight increase. The fire regime in central and western parts would have a significant increase.