普定喀斯特次生林木本植物叶生活型比例和谱系多样性的驱动因素

Drivers of the leaf habit ratio and phylogenetic diversities of woody plants in the secondary karst forests in Puding, Guizhou

关键词:  地形, 人类活动, 基岩类型, 群落构建, 乔木层, 叶生活型

Key words:  topography, human activities, bedrock type, community assembly, tree layer, leaf habit

摘要:

为探讨喀斯特森林落叶阔叶植物(DBL)与常绿阔叶植物(EBL)比例和生物多样性差异及其驱动因素,该研究以贵州省普定县43个喀斯特次生林样地作为研究对象,采用广义线性回归模型、模型选择和Mantel检验的多元回归方法,分析地理距离、环境(包括地形和基岩类型)和人类活动等因素对样地内落叶阔叶植物和常绿阔叶植物所占比例以及谱系多样性的影响。结果表明:(1)普定喀斯特次生林样地内落叶阔叶植物与常绿阔叶植物虽在物种丰富度和个体多度上总体相当,但样地间差异较大; 样地落叶与常绿阔叶植物谱系alpha多样性(即SES.MPD)无明显差异,但落叶阔叶植物谱系beta多样性(即SES.betaMPD)明显小于常绿阔叶植物。(2)落叶阔叶植物丰富度占比和相对多度随基岩类型改变而变化,均表现为泥灰岩森林高于石灰岩森林,而落叶阔叶植物丰富度占比随人类活动增强而上升。(3)样地落叶阔叶植物谱系alpha多样性随人类活动增强而升高,而常绿阔叶植物谱系alpha多样性受环境和人类活动等因素的作用不明显; 落叶阔叶植物和常绿阔叶植物谱系beta多样性受不同因素调节,前者随基岩类型和人类活动等因素变化而升高,后者则随地理距离增加而升高。该研究揭示了普定喀斯特次生林内落叶阔叶植物和常绿阔叶植物比例受到环境条件和人类活动共同调控,在此基础上,落叶阔叶植物谱系多样性受到地形和基岩类型等因素介导的生境过滤等生态位过程影响,而常绿阔叶植物谱系多样性则受到地理距离所介导的扩散限制等空间过程的影响。该研究有助于了解喀斯特森林生物多样性维持机制,为喀斯特森林经营管理提供理论支持。

Abstract:

In order to understand of the drivers of the ratio of deciduous broad-leaved plants(DBL)to evergreen broad-leaved plants(EBL)and the diversities of each leaf habit group in the karst forests, with 43 secondary karst forest sample plots in Puding County of Guizhou Province as study objects, we adopted statistical methods such as the generalized linear regression model, model selection and the multiple regression extension of the Mantel test, and we examined the effects of geographical distance, environment(including topography and bedrock type), and human activities on the proportion of DBL and EBL as well as their phylogenetic alpha and beta diversities. The results were as follows:(1)The DBL and EBL in puding were about equal in overall richness and abundance, but large differences existed among sample plots; the phylogenetic alpha diversity(i.e., SES.MPD)of DBL and EBL was not different, whereas the phylogenetic beta diversity(i.e., SES.betaMPD)of DBL between sample plots was smaller than EBL plants.(2)The richness ratio and relative abundance of DBL shifted with bedrock type, and displayed as the marlstone forests comprised higher richness ratio and relative abundance of DBL compared with limestone forests. In addition, the richness ratio of DBL also increased as human activities intensified.(3)The phylogenetic alpha diversity of DBL increased with the intensified human activities, whereas the phylogenetic alpha diversity of EBL was not influenced by the environmental factors and human activities, which might partly be due to the conserved resource utilization strategies of EBL that blunt their claim for the resources released by human disturbance. The phylogenetic beta diversities of DBL and EBL, however, were shaped by different sets of factors, the former increased with the change of bedrock type and the intensity of human activities, the latter increased with geographical distance. The findings imply that the ratio of DBL to EBL in the secondary karst forests of Puding are mainly driven by environment conditions and human activities, based on which the phylogenetic diversities of DBL are regulated by niche processes such as habitat filtering mediated by topography and bedrock type, whereas EBL are shaped by spatial processes such as dispersal limitation mediated by geographical distance. This study sheds light on the biodiversity maintenance mechanisms of karst forests, and provides theoretical support for the management of karst forests.