Moso bamboo invasion has contrasting effects on soil bacterial and fungal abundances, co-occurrence networks and their associations with enzyme activities in three broadleaved forests across subtropical China

Abstract

Moso bamboo (Phyllostachys edulis) invasions into adjacent forests have been reported to threaten aboveground biodiversity and alter belowground soil processes. However, the impacts of bamboo invasion on soil microbial community composition, co-occurrence network and enzyme activity remain largely unknown. We presented a cross site field investigation on soil bacterial and fungal communities and enzyme activities in three forests (an original broadleaf forest, a mixed bamboo-broadleaf forest and a pure bamboo forest) at three sites in South China. Our results showed that bamboo invasion consistently increased soil pH (by 6.72% − 17.56%) and soil organic carbon concentrations (by 11.75% − 40.63%) across the three sites. Bamboo invasion consistently decreased fungal ITS gene abundances across the sites, but had little effect on bacterial 16S rRNA gene abundances and diversity indices. The community composition of both bacteria and fungi and their functional guilds differed among the three sites and were significantly (P < 0.05) affected by bamboo invasion. Bamboo invasion significantly decreased the relative abundances of ectomycorrhizal but increased those of soil saprotrophs. The complexity of co-occurrence network of bacterial communities was increased whereas that of fungal communities was decreased due to bamboo invasion. The activities of soil enzymes involved in C, N and P cycling were also altered by bamboo invasion, and they were significantly positively correlated with the abundances of fungal ITS gene and ectomycorrhizal rather than those of bacteria and predicted metabolic function. This study suggested that bamboo invasions into adjacent broadleaf forests had contrasting effects on soil bacterial and fungal communities by shifting microhabitats towards a condition that is unfavorable for some fungal functional guilds, which were tightly associated with soil functioning. These results highlight the need for sustainable forestry management against bamboo invasion to maintain fungal diversity and network complexity.