模拟地表火行为对燃烧剩余物水溶性碳氮的影响

燃烧剩余物是火烧迹地土壤表面必然存在的残留物，可以通过降水过程以及地表径流释放其所含有的矿物质和有机质至土壤生态系统，从而在一定时间内持续地对火后生态系统恢复过程造成影响。但不同火行为下，相同的可燃物所产生的燃烧剩余物可能具有不同的生态学功能，为了认知火行为对燃烧剩余物的影响，进一步了解二者对火烧迹地生态恢复过程中养分循环和能量流动的潜在影响，探究了火行为对燃烧剩余物水溶性碳氮化学计量特征的影响。以红松人工林地表可燃物为实验材料，通过设置不同坡度和含水率为火行为的驱动因子，进行了森林可燃物床层地表上坡火和下坡火的室内模拟燃烧实验。用独立样本T检验、单因素方差分析、多因素方差分析探究了火环境对燃烧剩余物水溶性碳氮和火行为的影响，用基于距离的冗余分析(db-RDA)探究了火行为对燃烧剩余物水溶性碳氮化学计量特征的影响。上坡火实验组的燃烧剩余物水溶性碳氮含量明显高于下坡火实验组(P<0.01);5°实验组中，燃烧剩余物的水溶性碳含量随着可燃物预设含水率的升高而升高(P<0.05)。进一步的数据分析发现火行为与燃烧剩余物水溶性碳氮化学计量特征关系密切，火焰宽度是影响燃烧剩余物水溶性...

Effect of the simulated surface fire behavior on water-soluble carbon and nitrogen in ash

Ash is the inevitable residues on the soil surface in burned area. Mineral and organic matter of ash can be released into the soil ecosystem through precipitation and surface runoff, which is an important way for fire to indirectly affect the restoration process of the post-fire ecosystem during a certain period of time. However, the ash from the same fuels but produced by different fire behaviors may have different ecological functions. In order to understand the influence of fire behavior on ash and their potential effects on the nutrient cycle and energy flow in the process of ecological restoration of the burned areas, the influence of fire behavior on the ash stoichiometric characteristics of water-soluble carbon and nitrogen was explored. In this study, the surface fuel of Pinus koraiensis plantation was used as experimental materials, different slopes and fuel moisture content were set as the driving factors of fire behavior, and the indoor simulation combustion experiments of the upslope and downslope forest surface fire were performed on the combustion bed. The influence of fire environment on the stoichiometric characteristics of ash water-soluble carbon and nitrogen and fire behavior indicators was explored by the independent-samples t-test, One-way ANOVA, Multivariate ANOVA, while the distance-based Redundancy analysis was used to explore the relationship of fire behavior and the stoichiometric characteristics of ash water-soluble carbon and nitrogen. The water-soluble carbon and nitrogen content of ash in the upslope fire experiment group was significantly higher than that in the downslope fire experiment group (P<0.01); In the 5° experiment group, the water-soluble carbon and nitrogen content of the ash was increase with fuel moisture content (P<0.05). Further data analysis found that the fire behavior was closely related to the stoichiometric characteristics of the ash water-soluble carbon and nitrogen. The flame width was the most significant factor affecting the stoichiometric characteristics of ash water-soluble carbon and nitrogen, and the correlation coefficients with water-soluble carbon, nitrogen and the water-soluble carbon-nitrogen ratio of ash were:-0.515, -0.317, and -0.550 (P<0.05). The flame height and combustion efficiency were negatively correlated with the water-soluble carbon and nitrogen content of ash, the fire intensity was negatively correlated with the water-soluble carbon-nitrogen ratio of ash, and the duration was positively correlated with the ash water-soluble carbon and nitrogen content (P<0.01). The stoichiometric characteristics of ash water-soluble carbon and nitrogen from the Pinus koraiensis plantation were directly affected by fire behavior and indirectly affected by fire environment. Fire disturbance can have a continuously potential impact on the ecological restoration process of burned areas by affecting the characteristics of ash.