NOAA/WDS Paleoclimatology - Bigio fire data from Ashanga sawmill, Siberia - IMPD RUASH001

Every year, millions of hectares burn across Siberia, driven by a combination of warming temperatures, regional drought and human-caused ignitions. Dendrochronology provides a long-term context to evaluate recent trends in fire activity and interpret the relative influence of humans and climate drivers on fire regimes. We developed a 400-year record of fire-scarred trees from 17 sites in pine-dominated forests located southeast of Lake Baikal. Site-level mean fire return intervals (MFI) ranged from 4 – 27 years for all fires and 8 – 35 years for widespread fires within sites. Sites with the lowest MFI values were located within 1 km of agricultural fields in grassland valleys, suggesting that agricultural burning influenced MFIs at nearby sites. Fire frequency varied over the record, with significantly high values around 1790, from 1865 to 1880, 1948 to 1955 and 1995 to 2005. The increased fire activity corresponded with migration waves to the region and major socio-economic change connected with the establishment and breakdown of the Soviet Union. At broader scales, Superposed Epoch Analysis (SEA) showed that synchronous fire years were associated with regional drought and precipitation deficits. Wet conditions for two to three years prior to the event year were also significant, suggesting that increased moisture promoted growth of understory fine fuels to support more extensive fires across the study area. Although fire frequencies increased during the 20th century, fire-climate relationships weakened, suggesting increased human-caused ignitions may override the climate system. Our dataset presents a continuous record of fire over the past 400 years, providing a valuable opportunity to compare dendrochronology-based reconstructions with satellite and documentary records.

每年，西伯利亚地区均有数百万公顷的土地因气温升高、区域性干旱以及人为火源而发生野火。树木年代学（Dendrochronology）可为评估野火活动的近期趋势、解析人类与气候驱动因子对野火格局的相对影响提供长期视角。本研究于贝加尔湖东南部的针叶松主导森林中选取17个采样点，构建了长达400年的火疤树木记录。各采样点的平均火轮回期（Mean Fire Interval, MFI）整体介于4至27年（针对所有野火事件），而区域内大规模野火的平均火轮回期则为8至35年。平均火轮回期最短的采样点均位于草原河谷内的农田周边1公里范围内，这表明农业用火对邻近采样点的火轮回期产生了影响。野火发生频率在整个记录时段内存在显著波动，在1790年前后、1865年至1880年、1948年至1955年以及1995年至2005年期间达到显著高位。野火活动的增强时段与该地区的移民浪潮以及与苏联建立及解体相关的重大社会经济变革相吻合。在更大尺度下，叠加epoch分析（Superposed Epoch Analysis, SEA）结果显示，同步野火年份与区域性干旱及降水亏缺存在关联。事件发生前2至3年的湿润气候条件同样具有显著影响，这表明水分补给的增加会促进林下细燃料的生长，进而为研究区域内更大范围的野火提供发生条件。尽管20世纪野火发生频率有所上升，但野火与气候的关联却有所减弱，这表明人为火源的增加可能已超越气候系统的调控作用。本数据集提供了过去400年连续的野火记录，为基于树木年代学的野火重建结果与卫星观测及文献记录的对比提供了宝贵契机。