Carbon (C) emissions from wildfires are a key terrestrial–atmosphere interaction that influences global atmospheric composition and climate. Positive feedbacks between climate warming and boreal wildfires are predicted based on top-down controls of fire weather and climate, but C emissions from boreal fires may also depend on bottom-up controls of fuel availability related to edaphic controls and overstory tree composition. Here we synthesized data from 417 field sites spanning six ecoregions in the northwestern North American boreal forest and assessed the network of interactions among potential bottom-up and top-down drivers of C emissions. Our results indicate that C emissions are more strongly driven by fuel availability than by fire weather, highlighting the importance of fine-scale drainage conditions, overstory tree species composition and fuel accumulation rates for predicting total C emissions. By implication, climate change-induced modification of fuels needs to be considered for accurately predicting future C emissions from boreal wildfires.

野火产生的碳（C）排放是影响全球大气成分和气候的重要地-大气相互作用。基于自上而下的火天气和气候控制，可以预测气候变暖和北方野火之间的积极反馈，但是北方大火产生的C排放也可能取决于自下而上的对燃料控制性的控制，与可控性和过高的树木组成有关。在这里，我们综合了来自北美西北寒带森林六个生态区的417个现场的数据，并评估了自下而上和自上而下的C排放驱动因素之间的相互作用网络。我们的结果表明，碳的排放更受燃料供应的驱动，而不是火天气的驱动，这凸显了精细排水条件的重要性，过度树种的组成和燃料积累速率，以预测总碳排放量。言外之意，需要考虑气候变化引起的燃料改性，以准确预测北方野火造成的未来碳排放。