wildFIRE Lab, University of Exeter, Exeter, EX4 4PS, UK.
Botany Department, School of Natural Sciences, Trinity College Dublin, Dublin, D02 PN40, Ireland.
New Phytol. 2022 Aug;235(4):1442-1454. doi: 10.1111/nph.18299. Epub 2022 Jun 30.
The Triassic-Jurassic boundary marks the third largest mass extinction event in the Phanerozoic, characterized by a rise in CO -concentrations from c. 600 ppm to c. 2100-2400 ppm, coupled with a c. 3.0-4.0°C temperature rise. This is hypothesized to have induced major floral turnover, altering vegetation structure, composition and leaf morphology, which in turn are hypothesized to have driven changes in wildfire. However, the effects of elevated CO on fuel properties, such as chemical composition of leaves, are also important in influencing fire behaviour, but yet have not been considered. We test this by selecting three Triassic analogue species grown experimentally in different atmospheric compositions, and analyse variations in leaf chemistry, and leaf level flammability. These data were used to inform a fire behaviour model. We find that all three species tested showed a reduction in their volatile component, leading to lower flammability. Accounting for these variations in a model, our results suggest that leaf intrinsic flammability has a measurable impact on modelled fire behaviour. If scaled up to ecosystem level, periods of elevated CO may therefore be capable of inducing both biochemical and morphological changes in fuel properties, and thus may be capable of influencing fire behaviour.
三叠纪-侏罗纪交界标志着显生宙中第三大的大规模灭绝事件，其特征是 CO 浓度从约 600ppm 上升到约 2100-2400ppm，同时温度上升约 3.0-4.0°C。这被假设为引发了主要的植物更替，改变了植被结构、组成和叶片形态，而这又被假设为引发了野火的变化。然而，升高的 CO 对燃料特性的影响，如叶片的化学成分，对于影响火灾行为也很重要，但尚未得到考虑。我们通过选择三种在不同大气组成下进行实验生长的三叠纪模拟物种来检验这一点，并分析叶片化学性质和叶片级别的可燃性的变化。这些数据被用于为火灾行为模型提供信息。我们发现，所有三种测试的物种都表现出挥发性成分的减少，导致可燃性降低。在模型中考虑到这些变化，我们的结果表明，叶片内在可燃性对模型火灾行为有可测量的影响。如果扩展到生态系统水平，那么 CO 升高的时期可能有能力在燃料特性上引起生物化学和形态变化，从而可能影响火灾行为。
