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林业科学 ›› 2022, Vol. 58 ›› Issue (6): 110-121.doi: 10.11707/j.1001-7488.20220611

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兴安落叶松林火烧迹地地表枯落物燃烧性变化

王立轩,杨光*,高佳琪,郑鑫,李兆国,瓮岳太,邸雪颖,于宏洲   

  1. 东北林业大学林学院 森林生态系统可持续经营教育部重点实验室 哈尔滨 150040
  • 收稿日期:2020-12-28 出版日期:2022-06-25 发布日期:2022-09-24
  • 通讯作者: 杨光
  • 基金资助:
    国家自然科学基金项目(31870644);黑龙江省自然科学基金项目(LH2021C011)

Changes in the Flammability of Post-Fire Aboveground Litter of Larix gmelinii

Lixuan Wang,Guang Yang*,Jiaqi Gao,Xin Zheng,Zhaoguo Li,Yuetai Weng,Xueying Di,Hongzhou Yu   

  1. Key Laboratory of Sustainable Forest Ecosystem Management of Ministry of Education College of Forestry, Northeast Forestry University Harbin 150040
  • Received:2020-12-28 Online:2022-06-25 Published:2022-09-24
  • Contact: Guang Yang

摘要:

目的: 揭示地表枯落物燃烧性影响因素、层间关系及其变化趋势, 为北方森林火烧迹地燃烧性评估及其生态恢复提供数据支撑。方法: 选取大兴安岭塔河林场不同过火年份兴安落叶松天然林火烧迹地, 研究地表枯落物(未分解层和半分解层)理化性质(灰分含量、脂肪含量、热值)和酶含量(纤维素酶、半纤维素酶、木质素酶)2类指标, 采用单因素方差分析比较各恢复期枯落物燃烧性和酶含量的差异显著性, 采用皮尔森相关性和冗余分析探究各因子的相关关系, 采用配对样本t检验比较各层燃烧性和酶含量时间变化趋势, 采用线性回归方程拟合粗脂肪、灰分含量与热值耦合模型并采用直线斜率显著性检验验证层间斜率一致性。结果: 1) 枯落物层燃烧性随恢复时间不断提升, 在恢复后期粗脂肪含量和高位热值均显著高于对照组而灰分含量显著低于对照组; 半分解层各指标变化较明显。此外枯落物纤维素酶含量>半纤维素酶含量>木质素酶含量, 三者在火后恢复期均呈下降趋势。2) 坡向、坡位是枯落物层燃烧性的重要影响因素, 在阴坡和坡底枯落物层粗脂肪含量和高位热值较高, 灰分含量则与之相反。3) 各时期粗脂肪含量、高位热值未分解层显著高于半分解层; 灰分含量未分解层显著低于半分解层, 二者显著正相关; 未分解层去灰分热值、半纤维素酶、木质素酶、纤维素酶含量高于半分解层; 未分解层纤维素酶含量与半分解层显著正相关。4) 枯落物粗脂肪-热值和灰分-热值存在极显著线性关系, 半分解层粗脂肪-热值线性模型斜率显著高于未分解层, 两层灰分-热值模型斜率相同。结论: 火烧迹地地表枯落物燃烧性在火后16~27年恢复并超过原生境。未分解层燃烧性强于半分解层, 层间差异随恢复时长增加而减小。地形因子对地表枯落物燃烧性产生显著影响, 在探究与评估森林燃烧性时要因地制宜, 综合考量。纤维素酶含量可影响地表枯落物灰分、粗脂肪和热值。地表枯落物灰分含量和高位热值线性模型为y = 21.225 - 0.207 x (y为高位热值, x为灰分含量, P < 0.001, R2 = 0.908)拟合优度良好, 在进一步验证后可作为参考为快速估计地表可燃物热值和燃烧性、林火发生预测预报增添新途径。

关键词: 兴安落叶松, 火烧迹地, 地表可燃物, 燃烧性, 恢复时长, 环境因子, 酶含量

Abstract:

Objective: This study aims to reveal the influencing factors, inter-layer relationship and change trend of the flammability of surface litter, in order to provide data support for the assessment of the flammability of the northern forest burned area and its ecological restoration. Method: In this paper, the burned slash of natural Larix gmelinii forest in Tahe forestry bureau of Daxing'an Mountains was targeted. The physical and chemical properties (ash content, fat content and calorific value) and enzyme content (cellulase, hemicellulase and ligninase) of the aboveground litter were investigated. One way ANOVA was used to compare the significant differences in litter flammability and enzyme activities in each recovery period since fire. Pearson correlation and redundancy analysis were used to explore the correlation of each factor. Paired sample t-test was used to compare the temporal change trend of flammability and enzyme activity in litter and fermentative layer. Linear regression equation was used to fit the coupling model of crude fat, ash content and calorific value, and the linear slope significance test was used to verify the consistency of inter-layer slope. Result: 1) The flammability of litter layer increased with the recovery time, and the crude fat content and high calorific value were significantly higher than those of the control group in the late recovery period, while the ash content was significantly lower than that of the control group. The indexes of semi-decomposition layer changed obviously. In addition, the content of enzymes in the litter ranged as cellulase > hemicellulase > ligninase, and all the three enzymes showed a decreasing trend in the recovery period after fire. 2)The aspect and position of slope were important factors affecting the burning property of litter layer. The crude fat content and high calorific value of litter layer were higher in shady slope and bottom of slope, while ash content was opposite. 3)The crude fat content and higher heating value in litter were significantly higher than that in fermentative layer, and there was not significant correlation between them. The ash content in litter was significantly lower than that in fermentative layer, and there was significant positive correlation between them. The ash free calorific value, hemi cellulase, ligninase and cellulase content in litter were higher than those in fermentative layer, and there was no significant correlation between layers. There was a significant positive correlation between the content of cellulase in litter and fermentative layer. 4) There was a very significant linear relationship between crude fat content, ash content and higher heating value in litter. The slope of the model of crude fat content and higher heating value in fermentative layer was significantly higher than that in Litter, and the slope of the model of ash content and higher heating value was the same in two layers. Conclusion: The flammability of aboveground litter in burned area have recovered and exceeded the original habitat 16-27 years after the fire. The combustibility in litter is stronger than that in fermentative layer, and the difference between layers decreases as the recovery time increases. Terrain factors have a significant impact on the flammability of aboveground litter, thus it is necessary to make a comprehensive assessment of forest combustibility by multi factors in accordance with local conditions. Cellulase content can affect the ash content, crude fat and higher heating value of aboveground litter. The linear model of ash content and high calorific value of aboveground litter is y = 21.225 - 0.207 x (y is high calorific value, x is ash content, P < 0.001, R2 = 0.908), which has a good goodness of fit. After further verification, it can be used as a reference to add a new way to rapidly estimate calorific value and combustibility of surface fuel and predict forest fire occurrence.

Key words: Larix gmelinii, burned area, surface fuel, fermentative, time since fire, environmental factors, enzyme content

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