华北地区胡桃楸林分布规律及群落构建机制分析

探究植物分布规律和群落构建机制是揭示植物群落空间分布、群落物种多样性的形成、发展及其影响因素的重要途径。该文以华北地区胡桃楸(Juglans mandshurica)林为研究对象, 基于野外84个样方的调查数据, 通过径级分析、典范对应分析等方法研究了胡桃楸林的空间分布规律, 并通过亲缘关系指数计算、植物功能性状等方法研究了胡桃楸林的物种共存机制。结果表明, 华北地区胡桃楸的胸径相对较小(平均5.36 cm), 种群年龄较低; 海拔、坡度、坡位和人为干扰程度是影响华北地区胡桃楸分布的主要因子。研究区域内的胡桃楸大部分生长于山体中下部海拔较低的缓坡, 且人为干扰相对较少的区域, 各分布区域中胡桃楸林的分布规律各异。胡桃楸林物种的构建由生态位机制主导, 其中河北、陕西、天津的胡桃楸林物种共存过程主要受负密度制约的影响, 北京、山西的胡桃楸林的物种共存过程主要受环境选择驱动。

Species distribution and community assembly rules of Juglans mandshurica in North China

Aims Explore the distribution pattern and the processes controlling the assembly of the Juglans mandshurica dominated forests in North China.
Methods We investigated 84 plots, each with an area of 20 m × 30 m, for the J. mandshurica forests in the North China. We analyzed demography of the J. mandshurica based on its diameters, and applied canonical correspondence analysis (CCA) to explore the relationship between environment and species composition of different formations of the J. mandshurica forests. We then calculated phylogenetic index, i.e., net relatedness index (NRI) and nearest taxonomic index (NTI) and Gaussian Kernel Density Estimation (Gaussian KDE), for each plot to explore the rules controlling community assembly of these forests.
Important findings The population of J. mandshurica is relatively young in the Northern China, with a mean diameters at breast height (DBH) of 5.36 cm. Distribution of J. mandshurica in North China varied significantly with altitude, slope, slope position and human disturbance. Most of the J. mandshurica located at the low part of the massif with lower altitude and less human disturbance. In North China, niche related processes regulated species coexistence of Form. J. mandshurica, with competition controlled the community assembly in Hebei, Shaanxi and Tianjin, while environment filtering dominated in Beijing and Shanxi.