3. Tree-ring reconstructions of climate indices used in Bivariate Event Analyses (BEA) and 20th century records of average annual summer and winter temperature and precipitation from Seven hundred years of human-driven and climate-influenced fire activity in a British Columbia coastal temperate rainforest

While wildland fire is globally most common at the savannah-grassland ecotone, there is little evidence of fire in coastal temperate rainforests. We reconstructed fire activity with a 700-year fire history derived from fire scars and stand establishment from 30 sites in a very wet (more than 4000 mm average annual precipitation) temperate rainforest in coastal British Columbia, Canada. Drought and warmer temperatures in the year prior were positively associated with fire events though there was little coherence of climate indices on the years of fires. At the decadal scale, fires were more likely to occur after positive El Niño-Southern Oscillation and Pacific Decadal Oscillation phases and exhibited 30-year periods of synchrony with the negative phase of the Arctic Oscillation. Fire frequency was significantly inversely correlated with the distance from former Indigenous habitation sites and fires ceased following cultural disorganization caused by disease and other European impacts in the late nineteenth century. Indigenous people were likely the primary ignition source in this and many coastal temperate rainforest settings. These data are directly relevant to contemporary forest management and discredit the myth of coastal temperate rainforests as pristine landscapes.

尽管全球范围内野火在稀树草原-草原交错带（savannah-grassland ecotone）最为频发，但温带沿海雨林中几乎无火灾相关记录。本研究针对加拿大不列颠哥伦比亚省沿海一处年平均降水量超4000毫米的湿润温带沿海雨林，通过30个样点的火灾痕迹（fire scars）与林分建立数据，重建了长达700年的火灾历史，还原了该区域的火灾活动特征。研究发现，火灾发生前一年的干旱与升温与火灾事件呈显著正相关，但火灾年份的气候指数关联性较弱。在年代际尺度上，火灾更易发生在厄尔尼诺-南方涛动（El Niño-Southern Oscillation）与太平洋年代际振荡（Pacific Decadal Oscillation）正相位阶段，且与北极涛动（Arctic Oscillation）负相位呈现30年的同步周期。火灾发生频率与距离原原住民居住点的距离呈显著负相关；19世纪晚期，受疾病与欧洲殖民带来的其他影响导致原住民文化解体后，该区域的火灾便彻底停止。在该区域及诸多温带沿海雨林环境中，原住民大概率是主要的点火源。本研究数据可直接应用于当代森林管理实践，同时驳斥了"温带沿海雨林为原生未受干扰景观"的错误论调。