Water is a limiting factor in the restoration and construction of desert steppe. Exploring plant water sources is necessary to understand soil-plant interactions and species coexistence; however, water sources of major plant communities within the desert steppe of Ningxia Hui Autonomous Region, China remain poorly understood. In this study, we analyzed the water uptake of plants in four typical communities: Agropyron mongolicum Keng.; Sophora alopecuroids Linn.; Stipa breviflora Griseb., and Achnatherum splendens (Trin.) Nevski communities. Stable isotopes δD and δ18O in the xylem of plant and soil water at different soil depths were analyzed. An IsoSource model was used to determine the soil depths from which plants obtained water. Results showed that A. mongolicum community obtained water predominantly from 0–20 and 40–80 cm depth, S. alopecuroids community from 0–20 cm depth, S. breviflora community from 0–40 cm depth, and A. splendens community from 0–20 and 80–140 cm depths. S. alopecuroides had a wider range of soil depths for water extraction, i.e., utilizing different water sources depending on habitat, and the plasticity of its water uptake pattern determined its role in different communities. Water source of plants relayed heavily on the distribution of their roots. Competition for soil water exists between different plant life forms in the sierozem habitat (A. mongolicum, S. alopecuroids, and S. breviflora communities), and in the sandy soil habitat (A. splendens community). The use of soil water by A. splendens community is more spatially differentiated, and shrubs and herbs can coexist stably. Under the pattern of extended drought period in the future, sierozem habitat may be more favorable for the formation of a dominant monoculture community type of perennial fibrous plants. In aeolian sandy soil habitat, A. splendens had a strong competitive advantage, and the growth of shallow-rooted plants was easily suppressed.

CHEN Juan;WANG Xing;SONG Naiping;WANG Qixue;WU Xudong

School of Agriculture,Ningxia University,Yinchuan 750021,China;Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in northwestern China,Yinchuan 750021,China;Key Laboratory of Restoration and Reconstruction of Degraded Ecosystems in northwestern China of Ministry of Education,Yinchuan 750021,China;School of Ecology and Environment,Ningxia University,Yinchuan 750021,China;Institute of Desertification Control,Ningxia Academy of Agricultural and Forestry Sciences,Yinchuan 750002,China

干旱区科学

[1]CHEN Juan;WANG Xing;SONG Naiping;WANG Qixue;WU Xudong-.Water utilization of typical plant communities in desert steppe, China)[J].干旱区科学,2022(09):1038-1054

alopecuroids,relayed,sierozem

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