Chin J Plant Ecol ›› 2017, Vol. 41 ›› Issue (10): 1051-1059.DOI: 10.17521/cjpe.2017.0165

Special Issue: 稳定同位素生态学 青藏高原植物生态学:植物-土壤-微生物

• Research Articles • Previous Articles     Next Articles

Differential uptakes of different forms of soil nitrogen among major tree species in subalpine coniferous forests of western Sichuan, China

Ting-Ting ZOU1,2, Zi-Liang ZHANG1,2, Na LI1, Yuan-Shuang YUAN1,2, Dong-Hui ZHENG1,2, Qin LIU1, Hua-Jun YIN1,3,*()   

  1. 1Chengdu Institute of Biology, Chinese Academy of Sciences, Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization of Chinese Academy of Sciences, and Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu 610041, China

    2University of Chinese Academy of Sciences, Beijing 100049, China

    3College of Environmental Science and Engineering, China West Normal University, Nanchong, Sichuan 637000, China
  • Online:2017-10-10 Published:2017-12-24
  • Contact: Hua-Jun YIN

Abstract:

Aims Although acquisition of soil organic nitrogen (N)(mainly amino acids) by plants is a widespread ecological phenomenon in many terrestrial ecosystems, the rate of organic N uptake and their contributions to plant nutrient supply are poorly understood. Our objective was to determine the relative contributions of inorganic N (NO3-N and NH4+-N) and organic N (amino acids) to plant N uptake in a high-frigid forest ecosystem.Methods The differences in the uptake rate of three different forms of N (NO3-N, NH4+-N and glycine) were quantified by exposing seedlings of two dominant tree species (Picea asperata and Betula albo-sinensis) in subalpine coniferous forests of western Sichuan, China, to trace quantities of K15NO3,15NH4Cl and (U-13C2/15N) glycine.Important findings Both 13C and 15N were significantly enriched in fine roots 2 h after tracer application, indicating the occurrence of glycine uptake in P. asperata and B. albo-sinensis seedlings. The seedlings of two tree species had a significant preference for NO3-N compared with glycine and NH4+-N, and the uptake rate of NO3-N was 5 to 10 times greater than that of glycine and NH4+-N. The roots of seedlings in the two species took up glycine more rapidly than NH4+-N, implying that soil organic N (i.e., amino acids) could be an important N source for the two species in subalpine coniferous forests. The results of this study are of great theoretical significance for understanding N utilization strategies and nutrient regulation processes in plants of the high-frigid forest ecosystems.

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Key words: organic nitrogen, inorganic nitrogen, amino acid, stable isotope labeling, subalpine coniferous forest