平地无风条件下蒙古栎阔叶床层的火行为Ⅲ.火线强度、可燃物消耗和燃烧效率分析及预测模型

Fire behavior of Quercus mongolica leaf litter fuelbed under zero-slope and no-wind conditions.Ⅲ.Analysis and modelling of fireline intensity,fuel consumption,and combustion efficiency

以东北地区针阔混交林重要建群种和伴生种蒙古栎为对象,在平地无风条件下进行室内点烧试验,分析含水率、载量和厚度对蒙古栎凋落叶床层火线强度、消耗量和燃烧效率的影响,并对相关模型进行了验证.结果表明:含水率、载量和床层厚度对蒙古栎凋落叶床层火线强度、消耗量和燃烧效率均有显著影响,并且3个指标之间存在交互作用.在已有模型中,Byram模型需参数调整后方可用于本地凋落叶可燃物,其重新估计的α、β拟合值分别为98.009和1.099,得到的预测值均方根误差为8.676 kW·m-1,平均相对误差为21.0%,R2为0.745.对Albini提出的燃烧效率模型参数a、b的重新估计值分别为0.069和0.169,得到的预测值均在93.0%以上,绝大多数偏高.Consume模型适用性较强.新建立的火线强度、消耗量和燃烧效率的一般线性模型调整后的R2分别为0.82、0.73和0.53,均方根误差分别为8.266 kW·m-1、0.081 kg·m-2和0.203.在低强度地表火中,细小可燃物可能不会被完全消耗,现有一些系统中将凋落叶和细小可燃物按全部消耗处理,将高估碳的释放量.

Mongolian oak （Quercus mongolica） is an important constructive and accompanying spe- cies in mixed broadleaf-conifer forest in Northeast China, In this paper, a laboratory burning experi- ment was conducted under zero-slope and no-wind conditions to study the effects of fuel moisture content, loading, and thickness on the fireline intensity, fuel consumption, and combustion effi- ciency of the Mongolian oak leaf litter fuelbed. The fuel moisture content, loading, and thickness all had significant effects on the three fire behavior indices, and there existed interactions between these three affecting factors. Among the known models, the Byram model could be suitable for the prediction of local leaf litter fire intensity only after re-parameterization. The re-estimated α and β parameters of the re-parameterized Byram model were 98. 009 and 1. 099, with an adjusted determi- nation coefficient of 0. 745, the rooted mean square error （RMSE） of 8. 676 kW ·m-1 , and the mean relative error （MRE） of 21%, respectively （R2 =0. 745）. The re-estimated a and b by the burning efficiency method proposed by Albini were 0. 069 and 0. 169, and the re-estimated values were all higher than 93 %, being mostly overestimated. The Consume model had a stronger suitabi- lity for the fuel. The R2 of the general linear models established for fireline intensity, fuel consumption, and burning efficiency was 0.82, 0.73 and 0.53, and the RMSE was 8. 266 kW· m-1 0. 081 kg· m-2, and 0. 203 , respectively. In low intensity surface fires, the fine fuels could not be completely consumed, and thus, to consider the leaf litter and fine fuel in some forest ecosystems being completely consumed would overestimate the carbon release from forest fires.