秦岭太白红杉球果与种子特性及其与环境的关系

Cones and Seeds Characteristics of Larix chinensis in Qinling Mountains and Their Relationship with Environmental Factors

太白红杉(Larix chinensis)是研究秦岭高山林线与环境因子关系的理想树种,球果与种子特征易受基因和环境的共同影响,是决定林线迁移和分布格局的关键因素。应用单因素方差、多重比较分析坡向和居群间的球果与种子差异,采用变异系数和表型分化系数分析球果与种子特征的变异来源,运用Pearson相关系数、RDA排序分析球果与种子特征与环境因子的关系。结果表明:(1)南坡和北坡的球果与种子特征差异不显著,北坡4个球果与种子特征在不同居群间均存在显著差异(P<0.05),南坡的球果重和平均种子数在不同居群间差异显著(P<0.05);(2)南坡的变异系数和表型分化系数均高于北坡;且南北坡球果与种子特征表型分化系数(Vst)均小于0.5,说明变异主要存在于种群内,异质的生境是球果与种子差异的重要因素;(3)环境因子与太白红杉4个球果与种子特征相关系数的绝对值从大到小依次为:海拔>土壤速效钾>坡向>p H值>土壤碱解氮>土壤有机质>土壤速效磷>坡度;海拔与球果与种子特征平均相关性最强(r=-0.475),是限制太白红杉分布的重要因素。研究表明,球果与种子差异主要来自太白红杉对环境的响应,海拔是限制太白红杉分布的重要因素。该研究揭示了林线树种太白红杉分布的限制因素,为生长抑制假说提供了数据支撑,也为该物种的保护提供理论依据。

Larix chinensis is a timberline tree species in the Qinling Mountains, and its fruiting characteristics （i.e., seed and cone characteristics） can affect migration and also distribution patterns of the timberline. We tested the differentiation between southern and northern slopes in different communities by field investigation of the cones and seeds characteristics of L. chinensis in Qinling Mountains. We then calculated the variations of cones and seeds between slopes and among populations using One-way ANOVA and multiple comparison, and analyzed the resources of difference using coefficient of phenotypic variation and phenotypic differentiation （Vst）, and calculated the relationship between the cones and seeds and environmental factors using Pearson correlation and redundancy analysis （RDA）. （1）We found no sig- nificant change in cones and seeds characteristics between plants in the southern and northern slopes. The northern slope plants featured a significant variation in all cones and seeds characteristics among different populations, whereas in the southern slope, only cone weight and seed number per cone differed among different populations. （2） Phenotype variation and differentiation was larger in the southern than northern slope and the Vsts in both slopes were 〈0.5, so the cones and seeds characteristics varied mainly within populations. （3） We found a negative correlation between altitude and weight, length, and width of cones. As well, the mean correlation between altitude and fruiting characteristics was maximum （r=-0.475）, followed by soil K, slope, pH, soil N, organic matter, soil P and gradient. Redundancy analysis showed that the fruiting characteristics were largely affected by altitude, slope and soil K. These results may be helpful to explain the factors limiting the distribution of L. chinensis, providing theoretical evidence for management and protection.