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Chinese Journal of Applied Ecology ›› 2021, Vol. 32 ›› Issue (11): 4077-4084.doi: 10.13287/j.1001-9332.202111.035

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Variations of soil organic nitrogen fractions during degradation succession in the Gahai Wetland, Northwest China

TANG Yan-mei, MA Wei-wei*, LI Guang, XU Guo-rong, ZHANG Yue, PAN Ping-xin, SONG Liang-cui, LONG Yong-chun, CHANG Wen-hua   

  1. College of Fores-try, Gansu Agricultural University, Lanzhou 730070, China
  • Online:2021-11-15 Published:2022-05-15
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (31860143), 2019 Longyuan Youth Innovation and Entrepreneurship (LYRC2019-34), Science and Technology Innovation Foundation of Gansu Agricultural University(GAU-XKJS-2018-116), and Gansu Provincial Financial Special Fund (GSCZZ-20160909).

Abstract: This study amined to explore the variation of soil organic nitrogen components across the degradation succession of Gahai Wetland. By combining field sampling and laboratory analysis, the content and distribution characteristics of soil organic nitrogen components, i.e., hydrolytic total nitrogen (HTN), unidentified acidolytic nitrogen (HUN), ammonium nitrogen (AMN), amino acid nitrogen (AAN) and acid amino sugar nitrogen (ASN) were investigated in undegraded (UD), lightly degraded (LD), moderately degraded (MD), and heavy degraded (HD) Gahai Wetland. The results showed that, in the 0-10 cm layer, the contents of total nitrogen (TN), HUN, AMN, and AAN in LD decreased by 17.3%, 19.4%, 8.6%, and -5.6%, 28.0%, 19.4%, 17.1% and 0 in MD, and 35.8%, 28.8%, 28.6% and 55.6% in HD, respectively. In the 10-20 cm layer, the four components decreased by 4.0%, 10.3%, 2.9% and 9.1% in LD, 21.0%, 18.3%, -2.9% and -9.1% in MD, and 9.9%, 38.9%, 21.2% and 51.4% in HD, respectively. The corresponding contents in the 20-40 cm soil layer did not change. The proportion of soil acid-hydrolyzed nitrogen components to TN under four degradation stages was HUN (25.9%-32.5%) > AMN (6.7%-11.1%) > AAN (4.8%-11.1%) > ASN (1.2%-4.4%). Soil water content was the main driving factor for variations of soil organic nitrogen components as indicated by the results of redundancy analysis. Degradation of the Gahai Wetland significantly reduced the content of soil TN and the components of acid-hydrolyzed nitrogen in 0-10 cm soil layer, and weakened the nitrogen “sink” function of soils. The AAN and ASN were sensitive to wetland degradation.

Key words: Gahai, wetland degradation, acidolytic nitrogen, redundancy analysis.