武夷山风景名胜区森林地表可燃物含水率特征及其与环境因子的关系

Characteristics of forest surface fuel moisture contents and their relationships with environmental factors in Wuyi Mountain scenery district

以世界双遗产地武夷山风景名胜区内4种森林类型地表可燃物作为研究对象,采用外业调查与内业实验相结合的方法,对比分析地表可燃物含水率（绝对含水率与熄灭含水率）特征及其与地形、林分等14个影响因子的关系.结果显示：活地表可燃物绝对含水率、熄灭含水率在4种林型间差异较小,死地表可燃物差异较大,其中毛竹林在不同林型中绝对含水率较高,熄灭含水率较低,马尾松近成熟林则相反.在灌木、草本、1小时时滞可燃物（1 hr）、10小时时滞可燃物（10 hr）中,毛竹林绝对含水率大于熄灭含水率,不易点燃;马尾松近成熟林灌木、草本绝对含水率大于熄灭含水率,1 hr和10 hr可燃物绝对含水率〈熄灭含水率,容易点燃.绝对含水率中,不同坡向毛竹林的地表可燃物无显著差异,马尾松近成熟林仅在灌木、1 hr可燃物有差异,1 hr差异表现为阴坡〉阳坡.冗余分析（RDA）结果显示,活可燃物、死可燃物受不同的环境因子影响,环境因子对死可燃物含水率的解释量高于活可燃物.本研究结论表明,不同林型地表可燃物熄灭含水率比绝对含水率稳定,为评估景区森林点燃风险与火行为模拟提供了重要理论指导.

The characteristics of surface fuel moisture contents（absolute and extinction moisture contents） and their relationships with fourteen environmental factors such as terrain and stand were analyzed by combining field investigation with internal experiment in Wuyi Mountain scenery district, a World Heritage site. The results showed that the differences between absolute and extinction moisture contents of active surface fuel were relatively small; however, dead surface fuel showed an opposite trend in the four forest types. Bamboo forest had the highest absolute moisture content and lowest extinction moisture content, whereas near-mature Pinus massoniana forest showed an opposite trend. Shrub, herb, 1-hour dead fuel（1 hr）, and 10-hour dead fuel（10 hr） in bamboo forest were not flammable, because their absolute moisture content was greater than the extinction moisture content. Shrub and herb were also not flammable in near-mature P. massoniana forest, but 1 hr and 10 hr were flammable. No significant differences were found in surface fuel absolute moisture content of bamboo forest among different slopes, but significant differences were noted in shrub and 1 hr of near-mature P. massoniana forest： shady slopes had greater absolute moisture content than sunny slopes in 1 hr. Redundancy analysis indicated that active and dead fuels were affected by different environmental factors that had more influence on moisture content of the dead fuel than on that of active fuel. These results showed that the extinction moisture content of different forest surface fuel was stable relative to the absolute moisture content, which would provide a key theoretical guidance for assessing forest igniting risk and fire behavior simulation.