油松人工林林下植物群落变化及其环境解释

Changes of understory plant community in Pinus tabuliformis plantation and associated environmental explanations

通过对山西太岳山宋家沟油松(Pinus tabuliformis)人工林林下植物群落进行调查,采用典范对应分析(CCA),探讨油松人工林林下物种分布与环境因子之间的关系。结果表明:1)在调查的42个样地中,油松林下共出现植物物种83种,隶属26个科72属,其中草本层物种种类较灌木层物种种类丰富,多达64种。2)CCA排序较好地揭示了该区油松人工林林下植物的分布格局与环境梯度的关系:林龄、坡度、坡向、林冠郁闭度、全氮、全钾对油松人工林林下草本层物种分布格局有重要影响;林龄、坡向、坡度、全氮对油松人工林林下灌木层物种分布格局有重要的影响。3)影响林下草本层和灌木层物种分布格局的变量中,生境因子与生物因子共同分别解释了40.3%和42.7%,其中,纯粹的生境变量(即未与生物变量共有的空间变量)对林下植物群落的变异解释能力较生物变量高,表明生境因子在决定油松人工林林下植物分布格局变异中起着举足轻重的作用。

To better understand the relationship between the distribution of understory plants and environmental factors in Pinus tabuliformis plantation, the occurrence and distribution of under- story plants were investigated on 42 plots in Songjiagou of Taiyue Mountain, Shanxi Province, China. The environmental factors controlling understory plant composition and diversity were quantitatively assessed by the method of canonical correspondence analysis （CCA）. The results showed that： 1 ） 83 understory species belonging to 26 families and 72 genera were recorded on 42 plots. The number of species in the herb layer was more than 3 times of that in the shrub lay- er. 2） The results of CCA clearly reflected the relationship between the distribution of understory plants and environmental gradients. Forward variable selection showed that stand age, slope, slope aspect, canopy cover, total nitrogen and total potassium were important factors determining plant distribution in the herb layer, while stand age, slope aspect, slope, and total nitrogen were important in the shrub layer. 3 ） Habitat and biotic factors together explained 40.3% and 42.9% of variance in the distribution of herbaceous and shrub plants, respectively. Pure habitat factors exhibited a strong interpretation power for understory species distribution, suggesting that habitat factors might play an important role in the distribution variation of understory plants. The results of the study would provide a reference for scientific management, biological protection and sus- tainable utilization of P. tabuliformis plantation.