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Responses of soil microbial communities and functions associated with organic mineralization to nitrogen addition in a Tibetan grassland

journal contribution
posted on 2023-05-03, 18:44 authored by Ruyi Luo, Jiafa LuoJiafa Luo, Jianling Fan, Deyan Liu, Jin-Sheng He, Nazia Perveen, Weixin Ding
Alpine grasslands with a high soil organic carbon (SOC) storage on the Tibetan Plateau are experiencing rapid climate warming and anthropogenic nitrogen (N) deposition; this is expected to substantially increase the soil N availability, which may impact carbon (C) cycling. However, little is known regarding how N enrichment influences soil microbial communities and functions relative to C cycling in this region. We conducted a 4-year field experiment on an alpine grassland to evaluate the effects of four different rates of N addition (0, 25, 50, and 100 kg N ha−1 year−1) on the abundance and community structure (phospholipid fatty acids, PLFAs) of microbes, enzyme activities, and community level physiological profiles (CLPP) in soil. We found that N addition increased the microbial biomass C (MBC) and N (MBN), along with an increased abundance of bacterial PLFAs, especially Gram-negative bacterial PLFAs, with a decreasing ratio of Gram-positive to Gram-negative bacteria. The N addition also stimulated the growth of fungi, especially arbuscular mycorrhizal fungi, reducing the ratio of fungi to bacteria. Microbial functional diversity and activity of enzymes involved in C cycling (β-1,4-glucosidase and phenol oxidase) and N cycling (β-1,4-N-acetyl-glucosaminidase and leucine aminopeptidase) increased after N addition, resulting in a loss of SOC. A meta-analysis showed that the soil C/N ratio was a key factor in the response of oxidase activity to N amendment, suggesting that the responses of soil microbial functions, which are linked to C turnover relative to N input, primarily depended upon the soil C/N ratio. Overall, our findings highlight that N addition has a positive influence on microbial communities and their associated functions, which may reduce soil C storage in alpine grasslands under global change scenarios.


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© 2020 Soil Science Society of China. Published by Elsevier B.V. and Science Press


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Journal title





Luo, R., Luo, J., Fan, J., Liu, D., He, J.-S., Perveen, N., & Ding, W. (2020). Responses of soil microbial communities and functions associated with organic mineralization to nitrogen addition in a Tibetan grassland. Pedosphere, 30(2), 214–225. doi:10.1016/S1002-0160(19)60832-5