Journal of Resources and Ecology ›› 2020, Vol. 11 ›› Issue (2): 129-139.DOI: 10.5814/j.issn.1674-764x.2020.02.001

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Nitrogen Addition Decreases Soil Respiration without Changing the Temperature Sensitivity in a Semiarid Grassland

DU Wei, LI Yue, HE Pei, ZHANG Jiaqi, JING Haichao, NIE Cheng, LIU Yinghui*   

  1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
  • Received:2019-12-09 Accepted:2020-02-05 Online:2020-03-30 Published:2020-05-30
  • Contact: LIU Yinghui, E-mail: lyh@bnu.edu.cn
  • Supported by:
    The National Natural Science Foundation of China (31770519); The National Key Research and Development Program of China (2017YFC0503805).

Abstract: The mechanisms underlying the response of soil respiration (Rs) to nitrogen (N) addition remain to be explored in semiarid ecosystems. This study was conducted to determine the effect of N addition on soil microbial composition, Rs and the temperature sensitivity of Rs (Q10). The N addition experiment was carried out in a semiarid grassland in China, with N fertilizer application rates of 0, 2, 4, 8, 16, or 32 g N m-2 yr-1. Microbial phospholipid fatty acids (PLFAs), Rs and Q10 were measured, and their relationships with soil properties were determined for three growing seasons. The results showed that N addition significantly increased the content of soil dissolved organic carbon (DOC) and inorganic nitrogen (IN), and decreased soil pH. With respect to soil microbes, N addition reduced soil PLFAs, reduced the fungi to bacteria ratio (F:B) and increased the gram-positive bacteria to gram-negative bacteria ratio (G+:G-). Rs under the N2, N4, N8, N16 and N32 treatments decreased by 2.58%, 14.86%, 22.62%, 23.97% and 19.87%, respectively, compared to the N0 (control) treatment. The results of structural equation models showed that N addition reduced Rs by lowering soil PLFAs and altering the microbial composition. However, N addition had no significant effect on either Q10, soil total organic carbon (TOC) or total nitrogen (TN), indicating that N addition alleviated soil carbon loss and was unlikely to change the potential for a bigger loss under global warming.

Key words: nitrogen deposition, soil CO2 flux, Q10, phospholipid fatty acid, soil properties, Inner Mongolia grassland