Wei Pujie, Tang Li, Xiong Zixuan, Lamont Byron B, Chen Lin, Xue Weixing, Zhao Zeyao, Lu Wenxiong, Han Jisi, He Wanwan, Yang Wei, Yan Zhaogui
Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
Ecology Discipline, School of Molecular and Life Sciences, Curtin University, Perth, WA, 6845, Australia.
J Environ Manage. 2025 Feb;374:124053. doi: 10.1016/j.jenvman.2025.124053. Epub 2025 Jan 9.
The readiness of leaf-litter to burn in the presence of fire differs greatly between species. Thus, forests composed of different species vary in their susceptibility to fire. Fire susceptibility of forests may also differ from the arithmetic means of flammability of their component species, i.e., non-additive effects exist. Here, we assessed nine indices of flammability and five physicochemical properties of the leaf litter of eight common subtropical tree species in China. We then tested the net effects on litter flammability of different mixtures of the eight species. We measured the following variables: time to ignition, combustion time, spread rate, ignition temperature, mass loss, maximum flame height and three temperature indices, moisture, cellulose, lignin and ash contents, and specific leaf area (SLA). Our results show that the flammability of leaf litter: time to ignition, combustion time, ignition temperature, and flame height, varies widely between the eight species. Time to ignition was short (<3 s) for the three conifer species and Quercus variabilis and Q. aliena, but long (3.5-8.8 s) for Q. fabri, Q. glauca, and Liquidambar formosana. The five species with a short time to ignition all have high cellulose and lignin contents, and SLA, and are highly flammable. In contrast, the three species with long time to ignition have low cellulose and lignin contents, and SLA, and high ash content. Cellulose and lignin contents, and SLA are the major drivers of litter flammability, and ash and moisture contents are important negative drivers. Mixed litters containing species with high cellulose and lignin contents and SLA have positive non-additive effects (synergistic) on overall flammability whereas those containing species with low cellulose and lignin contents, and SLA have negative non-additive effects (antagonistic) on flammability. These results are essential for assessing forest fire-risks and assisting species selection in plantations or fire-break forests as a part of a forest fire-management strategy.
在有火源的情况下，不同树种的落叶易燃程度差异很大。因此，由不同树种组成的森林对火灾的易感性也各不相同。森林的火灾易感性也可能与其组成树种的可燃性算术平均值不同，即存在非加性效应。在此，我们评估了中国八种常见亚热带树种落叶的九个可燃性指标和五个物理化学性质。然后，我们测试了这八个树种不同混合物对落叶可燃性的净效应。我们测量了以下变量：着火时间、燃烧时间、蔓延速率、着火温度、质量损失、最大火焰高度和三个温度指标、水分、纤维素、木质素和灰分含量以及比叶面积（SLA）。我们的结果表明，落叶的可燃性：着火时间、燃烧时间、着火温度和火焰高度，在这八个树种之间差异很大。三种针叶树种以及栓皮栎和槲栎的着火时间较短（<3秒），但白栎、青冈和枫香的着火时间较长（3.5 - 8.8秒）。着火时间短的五个树种都具有高纤维素、木质素含量和比叶面积，且易燃性高。相比之下，着火时间长的三个树种纤维素和木质素含量低、比叶面积低且灰分含量高。纤维素和木质素含量以及比叶面积是落叶可燃性的主要驱动因素，而灰分和水分含量是重要的负驱动因素。含有高纤维素、木质素含量和比叶面积树种的混合落叶对整体可燃性有正的非加性效应（协同作用），而含有低纤维素、木质素含量和比叶面积树种的混合落叶对可燃性有负的非加性效应（拮抗作用）。这些结果对于评估森林火灾风险以及在人工林或防火林中辅助物种选择作为森林火灾管理策略的一部分至关重要。
