Linking Phyllostachys edulis (moso bamboo) growth with soil nitrogen cycling and microbial community of plant-soil system: Effects of plant age and niche differentiation

Understanding the impacts of plant age on bamboo growth, soil nutrient and functional microorganism can assist in the development of management practices to maximize the benefits of nutrients and functional endophytic and soil microbes in moso bamboo plantations. In this study, moso bamboos of different ages (0.5, 2.5, 4.5 and 6.5 years) were selected. The above-ground biomass, soil properties and endophytic microbes of above-ground tissue and stump root of different age bamboos were quantified, and their interactive relationships were also examined. There were negligible differences in the heights and above-ground fresh biomass among the bamboo plants of different ages, but net nitrogen (N) mineralization and potential nitrification rates of soils were significantly affected by the bamboo ages. The soil nprA gene abundances decreased with the bamboo ages, and soil AOB amoA gene abundances of the 0.5-yr bamboo were significantly higher than those of the other older plants. Average soil urease activities of the 2.5-yr, 4.5-yr and 6.5-yr bamboos were 81.4%, 81.1% and 88.2% lower than those of the 0.5-yr bamboo, respectively. Bacterial diversity indices and richness estimators in the soils were significantly higher than those in the above-ground tissues. Endophytic microbial community structures were more sensitive to the bamboo ages than the soil counterparts, and endophytic microbial community diversities and structures in the above-ground tissues were significantly changed with the bamboo ages. Bacterial and fungal community structures in the above-ground tissues were significantly different from those in the soils. Bamboo ages significantly affected the N transformations in the soils and endophytic community structures, but niche differentiations among the above-ground tissue, stump root and soil outweighed the plant ages in shaping the whole microbial communities of plant-soil system.