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

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.

Keywords

• topography
• human activities
• bedrock type
• community assembly
• tree layer
• leaf habit