飞播马尾松林林下植被组成、多样性及其与环境因子的关系

Relationships between the composition and diversity of understory vegetation and environmental factors in aerially seeded Pinus massoniana plantations

以飞播马尾松(Pinus massoniana)林为研究对象,采用冗余分析(RDA)和方差分解法分析林下植被物种组成及其多样性与环境因子的关系。结果表明:林下植物共54种,隶属29科36属,灌木、草本层物种重要值分别以算盘子(Glochidion puberum)和铁芒萁(Dicranopteris linearis)最高;前向选择及蒙特卡洛(Monte Carlo)检验表明,平均胸径、海拔、郁闭度对灌木层物种组成影响显著(P<0.05),土层厚度对草本层物种组成影响极显著(P<0.01);Monte Carlo检验预选出的9个因子共解释了物种多样性变异的70.9%,其中平均胸径、郁闭度、土层厚度、速效氮和坡位是影响林下植被物种多样性的主要环境因子;生物因子、非生物因子对物种多样性的单独解释率分别为34.8%和7.5%,两者交互作用解释率为20.5%,表明生物因子及其与非生物因子的共同作用是影响林下植被物种多样性的主要因素。

We chose the aerially seeded Pinus massoniana plantations to study the relationships between the composition and diversity of understory vegetation and environmental factors using the redundancy analysis （RDA） and variation partitioning methods. Our results showed that ： （ 1 ） A total of 54 understory species belonging to 29 families and 36 genera were recorded, and the im- portance values of Glochidion puberum and Dicranopteris linearis were the highest in shrub and herb layers, respectively. Significant effects of average diameter at breast height （ DBH）, altitude and canopy density on species composition in shrub layer, and extremely significant effects of soil thickness on species composition in herb layer were found （P〈0.01） using the forward selection and Monte Carlo analysis. （2） Nine factors selected by using Monte Carlo permutation test ex- plained together 70.9% of species diversity variation, and average DBH, canopy density, soil thickness, available nitrogen and slope position were the important factors determining species di- versity in understory vegetation. The biotic, abiotic factors and their interaction respectively ex- plained 34.8%, 7.5% and 20.5% of the total variation in species diversity in understory vegeta- tion, which indicated that biotic factors and their interactions with abiotic factors were the main factors affecting the species diversity in understory vegetation.