鼎湖山南亚热带常绿阔叶林叶功能性状沿群落垂直层次的种内变异

Intraspecific variation of leaf functional traits along the vertical layer in a subtropical evergreen broad-leaved forest of Dinghushan

探究功能性状沿着环境梯度如何变化一直以来是基于性状的群落生态学的核心问题之一。尽管功能性状存在种内和种间变异,但种内变异沿环境梯度如何变化仍有待探究。本文以鼎湖山南亚热带常绿阔叶林1.44 ha塔吊样地内16个树种的2,820个个体为研究对象,探究4种叶功能性状(比叶面积、叶干物质含量、叶厚度和叶面积)沿群落垂直层次的种内变异。首先,利用随机效应线性模型量化塔吊样地内的种内变异和种间变异;其次,利用Kmeans函数将森林的垂直层次划分为灌木层、亚冠层和林冠层,并通过构建回归模型探究叶功能性状在群落垂直层次中的种内变异格局。最后,应用混合线性模型和单因素方差分析的方法探究叶功能性状沿垂直层次的种内变异是否具有物种依赖性。结果表明:在局域群落中,并非所有叶功能性状的种内变异都低于种间变异;叶功能性状在不同垂直层次的种内变异格局存在显著差异,且种内变异与垂直范围呈正相关;叶功能性状的种内变异具有较强的物种依赖性,因此树种差异相对于小环境解释了更多的性状变异;此外,不同叶功能性状的种内变异沿垂直层次的变化趋势并不一致。本研究发现种内变异对于物种共存具有重要作用。

Exploring how functional traits vary along environmental gradients has always been one of the core issues of trait-based community ecology. While functional traits vary both among species and within species, little is known about how intraspecific variation changes along environmental gradients. We explored how intraspecific trait variations of four leaf functional traits(specific leaf area, leaf dry matter content, leaf thickness, leaf area) varied along vertical layer within community using data for 2,820 individuals belonging to 16 species in a 1.44-ha plot in the south subtropical evergreen broad-leaved forest in Dinghushan. First, we quantified the relative importance of intra-and interspecific trait variation within the canopy crane plot using linear random effect model. Trees were classified into three categories: shrub, subcanopy, canopy using the Kmeans method and investigated the patterns of intraspecific trait variation in different vertical layer using regression models. Finally, we explored whether intraspecific trait variation in different vertical layers depended on species differences using linear mixed effect models and a one-way analysis of variance. Results suggest that general intraspecific trait variation was lower than interspecific variation in the local community. Moreover, the pattern of intraspecific trait variation differed significantly among different vertical layer, and intraspecific trait variation was positively correlated with the vertical range. Intraspecific variation of leaf functional traits strongly depended on species differences, so species differences were relatively more important than microenvironment in explaining trait variation. In addition, intraspecific variation of different leaf functional traits showed different trends along vertical layer. Our study found the important role of intraspecific trait variation in species coexistence.