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Acta Prataculturae Sinica ›› 2021, Vol. 30 ›› Issue (6): 64-72.DOI: 10.11686/cyxb2020245

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Impact of nitrogen addition on stoichiometric characteristics of herbaceous species in desert steppe

Ying MA1(), Zhi-hao XU1, Qiao-hong ZENG1, Jian-long MENG2, Ya-hu HU1(), Jie-qiong SU3   

  1. 1.College of Earth and Environmental Sciences,Key Laboratory for Environmental Pollution Prediction and Control,Gansu Province,Lanzhou University,Lanzhou 730000,China
    2.Gansu Huading Environmental Protection Technology Co. ,Ltd. ,Linxia 731199,China
    3.Shapotou Desert Research and Experiment Station,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China
  • Received:2020-05-26 Revised:2020-07-16 Online:2021-05-21 Published:2021-05-21
  • Contact: Ya-hu HU

Abstract:

In order to study the nutrient utilization strategies and the changes in carbon (C) assimilation ability and distribution pattern of desert herbaceous plants after increased nitrogen (N) deposition, the changes of root and shoot stoichiometric ratio of different functional plant groups were analyzed under N addition in a typical desert steppe on the southeastern fringe of the Tengger Desert. It was found that the addition of N significantly increased the contents of soil total N, soil ammonium N, and plant N, and promoted the uptake of phosphorus (P) by perennials, especially forbs, but significantly decreased the content of P in roots of annuals. After N addition, the C content of annuals and perennial forbs decreased significantly, while the C content of perennial grasses showed an obvious shoot-root difference, in which the C content of shoot decreased significantly, while that of the roots increased significantly. The C∶N and C∶P ratios in plants of the different functional groups (except for the C∶P in roots of annuals) significantly decreased after the addition of N, and in both cases the tendency was for the root decrease to be greater than that of the shoot. In addition, the N∶P ratio in plants significantly increased after the addition of N. In particular, the changes for annuals with improved fertilization level were more significant. Therefore, in the N-limited desert steppe studied, the improvement of soil N availability resulting from exogenous N input will highlight the restrictive effect of P on plant growth, reduce the C assimilation per unit N of herbaceous plants and enhance the distribution of C to plant roots.

Key words: nitrogen deposition, desert steppe, plant functional groups, ecological stoichiometry, soil phosphorus