4. The supporting residual western redcedar chronology sampled from the study site and used in climate analyses 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.

尽管全球范围内野外野火（wildland fire）最频发于稀树草原-草原交错带（savannah-grassland ecotone），但沿海温带雨林中野火活动的相关记录却极为稀少。本研究依托加拿大不列颠哥伦比亚省沿海一处年均降水量超4000毫米的湿润温带雨林内的30个采样点，通过树木火疤（fire scars）与林分建立（stand establishment）数据，重建了该区域700年的野火活动历史。尽管野火发生当年的气候指数关联性较弱，但前一年的干旱与升温与野火事件呈显著正相关。在年代际尺度上，野火更易出现于厄尔尼诺-南方涛动（El Niño-Southern Oscillation）与太平洋年代际振荡（Pacific Decadal Oscillation）正相位之后，且与北极涛动（Arctic Oscillation）负相位存在30年的同步周期。野火发生频率与距原原住民居住遗址的距离呈显著负相关；19世纪末，受疾病与其他欧洲殖民影响导致原住民文化解体后，该区域野火活动彻底终止。在本研究区域乃至众多沿海温带雨林环境中，原住民极可能是野火的主要点火源。本数据集可为当代森林管理提供直接参考，同时驳斥了‘沿海温带雨林属于原始未受干扰自然景观’的错误认知。