亚热带树种多样性与凋落物层持水能力的关系

Relationship between tree species diversity and water holding capacity of litter layer in subtropical region

凋落物层作为森林土壤的“皮肤”,具有涵养水源、保持水土的功能。本研究以亚热带地区枫香、米老排、苦槠、红锥、杉木、马尾松、福建柏、南方红豆杉8个树种的纯林及其不同组合的混交林为研究对象,分析树种丰富度、功能多样性和群落加权平均性状与凋落物现存量、最大持水率、有效拦蓄量的关系。结果表明:各树种组合中,未分解层最大持水率、现存量和有效拦蓄量的范围分别为0~419%、0~0.58 t·hm^(-2)、0~1.66 t·hm^(-2);半分解层最大持水率、现存量和有效拦蓄量的范围分别为0~375%、0~6.14 t·hm^(-2)、0~16.03 t·hm^(-2)。树种丰富度和群落加权平均比叶面积对凋落物现存量和有效拦蓄量具有显著的正效应,群落加权平均叶氮含量对凋落物现存量具有显著的负效应。最大持水率随着比叶面积的多样性和群落加权平均比叶面积的增加而增加,随着群落加权平均叶片厚度的增加而降低。结构方程模型表明,树种丰富度通过增加比叶面积的多样性提高凋落物层持水能力;群落加权平均比叶面积通过增加凋落物现存量和最大持水率提高凋落层持水能力。在亚热带地区人工林的经营中,可以选择群落水平上具有较高比叶面积的混交林来提高凋落物层的持水能力。

Litter layer,serving as the“skin”of forest soil,plays a crucial role in conserving water resources and maintaining soil and water conservation.We analyzed the relationship of tree species richness,community weighted mean traits,and functional diversity with the standing mass,maximum water holding rate,and effective water sto-rage capacity of litters from various tree species including Liquidambar formosana,Mytilaria laosensis,Castanopsis sclerophylla,Castanopsis hystrix,Cunninghamia lanceolata,Pinus massoniana,Fokienia hodginsii,Taxus wallichiana and their combinations of mixed forests in subtropical region.The results showed that across various tree species combinations,the ranges of maximum water holding rate,standing litter mass and effective water storage capacity of undecomposed layer were 0-419%,0-0.58 t·hm^(-2),and 0-1.66 t·hm^(-2),respectively.For the semi-decomposition layer,these values spanned in 0-375%,0-6.14 t·hm^(-2),and 0-16.03 t·hm^(-2),respectively.Tree species richness and community weighted mean specific leaf area had significantly positive effects on standing mass of litter and effective water storage capacity,while community weighted mean leaf N content had significantly negative effect on standing mass of litter.The maximum water holding rate increased with the increases of functional diversity of specific leaf area and community weighted mean specific leaf area,decreased with the increase of community weighted mean leaf thickness.Results of structural equation model showed that tree species richness increased litter water holding capacity by increasing functional diversity of specific leaf area.The community weighted mean specific leaf area increased the water holding capacity of litter layer by increasing standing mass of litter and the maximum water holding rate.It is necessary to consider planting mixed forest with higher community weighted mean specific leaf area in the management of subtropical artificial forest,so as to improve the water holding capacity of litter layer.