Seasonal linkages between soil nitrogen mineralization and the microbial community in broadleaf forests with Moso bamboo (Phyllostachys edulis) invasion

Abstract

Plant invasions significantly alter the microbiome of the soil in terms of fungal and bacterial communities, which in turn regulates ecosystem processes and nutrient dynamics. However, it is unclear how soil microbial communities, nitrogen (N) mineralization, and their linkages respond to plant invasions over the growing season in forest ecosystems. The present study investigated the seasonal associations between the microbial composition/function and net N mineralization in evergreen broadleaf, mixed bamboo-broadleaf, and Moso bamboo (Phyllostachys edulis) forests, depicting uninvaded, moderately invaded, and heavily invaded forests, respectively. The ammonification and nitrification rates in the bamboo forest were significantly higher than those in the broadleaf and mixed bamboo-broadleaf forests during the spring season only. The forest type and seasonal variation significantly influenced the net rates of ammonification and nitrification and the abundances of bacterial apr and AOB amoA, fungal cbhI and lcc genes, as well as the microbial composition. Moreover, the partial least squares path model revealed that bamboo invasion enhanced net ammonification through increasing total N and fungal-to-bacterial ratio, and enhanced net nitrification through modifying the bacterial composition and increasing the fungal-to-bacterial ratio during spring. However, microbial parameters had no significant effect on net ammonification and nitrification during autumn. We conclude that shifts in the microbial abundance and composition following bamboo invasion facilitated soil N mineralization during spring, contributing to the rapid growth of Moso bamboo at the beginning of the growth season and its invasion into adjacent subtropical forests.