Altered diversity and functioning of soil and root-associated microbiomes by an invasive native plant.
Purpose: Microorganisms that inhabit at microhabitat of bulk soil, rhizosphere, and root play different roles in carbon and nutrient cycling, and their changes have differential impacts on plant community dynamics. However, there is an extensive knowledge deficit regarding how plant invasion affects soil microorganisms residing at different microhabitats of plant species being invaded and even those of the invader itself. Methods: This study employed high-throughput sequencing of bacterial 16S rRNA genes and the fungal internal transcribed spacer (ITS) region to investigate the microbial community structure and function(s) of bulk soil, rhizosphere, and roots of a dominant native tree species (Cyclobalanopsis glauca) in a subtropical evergreen forest invaded and uninvaded by an invasive native species (Phyllostachys edulis, Moso bamboo), and that of the invader itself at both invaded and uninvaded forests. Moreover, we calculated the α-, β-diversity and phyla composition and predicted the function and co-occurrence network of microbes. Results: The bacterial richness rather than fungal richness in bulk soil was observed to have increased after being invaded by bamboo. Both richness and co-occurrence network of the root-associated microbiomes of C. glauca declined after being invaded by bamboo, with a more drastic change in the rhizosphere than in roots. In the case of the bamboo, it was observed that bacterial networks had strengthened after they were invaded into the ambient forest as opposed to when they were in a monoculture, with a heavier change in root than in the rhizosphere. Furthermore, the changes in the root-associated microbial composition of C. glauca were mainly relevant for nutritional cycling, particularly bacteria responsible for nitrogen (N) cycling, implying the strengthened competition of C. glauca for nutrients after being invaded by bamboo. Conclusion: This study revealed that the invasion of bamboo resulted in significant but differential changes in microbial community structure and related functions that were inhabited within the bulk soil, and at the rhizosphere, and roots of both dominant native tree species and the bamboo itself. A more profound observation was made where the invasive and non-invasive plants showed contrasting responses between rhizosphere and root after invasion or being invaded, with the rhizospheric microbes of non-invasive plants being more sensitive than that of roots, and the roots of invader were more sensitive than rhizosphere. The study findings have important implications for soil carbon and nutrients cycling and even community development of subtropical evergreen forests.