南亚热带森林不同林型功能性状分布格局及其驱动机制

Distribution Pattern of Functional Traits and Mechanisms in Different Forest Types of South Subtropics

摘要:

植物功能性状能反映植物对环境变化的响应，研究植物功能性状的分布格局有助于揭示群落的构建过程及其内在作用机制。该研究以鼎湖山南亚热带山地常绿阔叶林和沟谷雨林为研究对象，采集并测量了样地中木本植物的12种不同的功能性状，分别以5 m×5 m、10 m×10 m、20 m×20 m的样方为尺度单元，通过计算平均成对性状距离指数来探讨群落中功能性状的分布格局及其驱动机制。结果表明, 两个林型的群落中12个功能性状均存在不同程度变异，但功能性状在群落间的差异不显著(P>0.05)。两个林型的群落中功能性状空间分布格局均具有尺度依赖性，但不同尺度的驱动机制有差异，随着空间尺度的增大，山地常绿阔叶林的功能性状空间分布格局主要驱动机制由环境过滤转为扩散限制；沟谷雨林的由环境过滤和相似性限制转为扩散限制，两个林型在20 m×20 m空间尺度上都是扩散限制。生态位分化和扩散限制综合作用于鼎湖山南亚热带山地常绿阔叶林和沟谷雨林的群落功能性状分布格局的产生及其群落构建过程，二者的贡献作用会随空间尺度发生变化。坡度是影响山地常绿阔叶林功能性状分布格局的最关键地形因子，海拔是影响沟谷雨林的最关键地形因子。

Abstract:

The growth, survival, reproduction, and spread of plants are significantly influenced by functional traits. Understanding the distribution pattern of plant functional traits is helpful to reveal the process of community construction and its internal mechanism. Twelve different functional traits of woody plants in Dinghu Mountain subtropical mountain evergreen broad-leaved forest and gully rainforest were collected and measured. The quadrats of 5 m×5 m, 10 m×10 m and 20 m×20 m were used as scale units, respectively. The distribution pattern and driving mechanism of functional traits in communities were investigated by calculating mean pairwise trait distance (PW). The results showed that the 12 functional traits of the two forest types had different degrees of variation, but there was no significant difference between the communities (P>0.05). The spatial distribution pattern of functional traits in the two forest types was scale dependent, but the driving mechanism was different at different scales. With the increase of spatial scale, the main driving mechanism of spatial distribution pattern of functional traits in the mountain evergreen broad-leaved forest changed from environmental filtering to diffusion restriction. The environmental filtering and similarity restriction of ravine rainforest were changed to diffusion restriction, and both forest types were diffusion restriction at the spatial scale of 20 m×20 m. Niche differentiation and dispersal restriction were involved in the formation of community functional traits distribution pattern and community construction in the subtropical mountain evergreen broad-leaved forest and gully rainforest in Dinghu Mountain, and the contribution of both changes with spatial scale. Slope is the most important topographic factor affecting the distribution pattern of functional traits in mountain evergreen broad-leaved forest, and elevation is the most important topographic factor affecting gully rainforest.