Effects of nitrogen addition on microbial residues and their contribution to soil organic carbon in China’s forests from tropical to boreal zone

• Published in: Environmental pollution (1987) Vol. 268; no. Pt B; p. 115941
• Main Authors: Ma, Suhui, Chen, Guoping, Du, Enzai, Tian, Di, Xing, Aijun, Shen, Haihua, Ji, Chengjun, Zheng, Chengyang, Zhu, Jianxiao, Zhu, Jiangling, Huang, Hanyue, He, Hongbo, Zhu, Biao, Fang, Jingyun
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2021
• Subjects: Amino sugars; Carbon - analysis; China; Ecosystem; Fertilization; Forests; Microbial biomass; Microbial necromass; Nitrogen - analysis; Nitrogen deposition; Soil; Soil Microbiology; Soil nitrogen; China; Microbial necromass; Nitrogen deposition; Fertilization; Amino sugars; Microbial biomass; Soil nitrogen
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2020.115941

Atmospheric nitrogen (N) deposition has a significant influence on soil organic carbon (SOC) accumulation in forest ecosystems. Microbial residues, as by-products of microbial anabolism, account for a significant fraction of soil C pools. However, how N deposition affects the accumulation of soil microbial residues in different forest biomes remains unclear. Here, we investigated the effects of six/seven-year N additions on microbial residues (amino sugar biomarkers) in eight forests from tropical to boreal zone in eastern China. Our results showed a minor change in the soil microbial residue concentrations but a significant change in the contribution of microbial residue-C to SOC after N addition. The contribution of fungal residue-C to SOC decreased under low N addition (50 kg N ha−1 yr−1) in the tropical secondary forest (−19%), but increased under high N addition (100 kg N ha−1 yr−1) in the temperate Korean pine mixed forest (+21%). The contribution of bacterial residue-C to SOC increased under the high N addition in the subtropical Castanopsis carlesii forest (+26%) and under the low N addition in the temperate birch forest (+38%), respectively. The responses of microbial residue-C in SOC to N addition depended on the changes in soil total N concentration and fungi to bacteria ratio under N addition and climate. Taken together, these findings provide the experimental evidence that N addition diversely regulates the formation and composition of microbial-derived C in SOC in forest ecosystems. [Display omitted] •Soil microbial residues in forests showed minor changes under N addition.•Microbial residue C in SOC increased under N addition in a subtropical forest.•Bacterial residue C in SOC was increased by N addition in subtropical and temperate forests.•Response of microbial derived C in SOC depended on soil N, fungi/bacteria and climate. Nitrogen additions showed a minor effect on microbial residues, but significantly changed the contribution of microbial residue carbon to soil organic carbon in forests.