Plant invasion drives liana and tree community assemblages and liana-tree network structure in two moist semi-deciduous forests in Ghana

摘要

Invasive plants are one of the greatest threats leading to biodiversity loss and species extinction worldwide. Understanding the responses of liana and tree communities as well as liana-tree interactions to plant invasion could be important in biodiversity conservation and ecosystem functioning, but there is limited knowledge on this subject matter. We therefore sought to determine how the diversity, composition and structure of native liana and tree communities and liana-tree interaction networks responded to invasion by three tree species (Broussonetia papyrifera, Cedrela odorata, Tectona grandis) in two moist semi-deciduous forests in Ghana. Effects of plant invasion on native liana and tree community structure and liana-tree network structure were quantified by sampling liana species with diameter at 1.30 m from rooting base >= 1 cm, and tree species with diameter at breast height >= 5 cm in 20 20 x 20 m plots each in non-invaded and invaded sites. The findings of the study showed that plant invasion was associated with lower diversity and abundance of lianas and trees as well as shifts in species composition of the plants. Our results revealed that plant invasion influenced the patterns of liana-tree network structure, and tended to cause an increase in network connectance and nestedness, and a decrease in network modularity and specialisation. Plant invasion drove the topological roles of a few liana and tree species in the invaded sites. Generally, species abundance and specificity were important correlates of nestedness, and modularity and species roles of the networks. We conclude that the invasive tree species drove native liana and tree community structure, degree of liana-tree network structure, and species topological roles, all of which may have adverse consequences on biodiversity in the forests.