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Spatio-temporal variations determine plant–microbe competition for inorganic nitrogen in an alpine meadow
Article first published online: 19 JAN 2011
DOI: 10.1111/j.1365-2745.2010.01789.x
© 2011 The Authors. Journal of Ecology © 2011 British Ecological Society
Additional Information
How to Cite
Xu, X., Ouyang, H., Richter, A., Wanek, W., Cao, G. and Kuzyakov, Y. (2011), Spatio-temporal variations determine plant–microbe competition for inorganic nitrogen in an alpine meadow. Journal of Ecology, 99: 563–571. doi: 10.1111/j.1365-2745.2010.01789.x
Publication History
- Issue published online: 15 FEB 2011
- Article first published online: 19 JAN 2011
- Received 29 June 2010; accepted 3 December 2010 Handling Editor: Marcel van der Heijden
Keywords:
- 15N tracer;
- alpine Kobresia meadow;
- ammonium;
- inorganic N;
- nitrate;
- plant–microbe competition;
- plant–soil (below-ground) interactions;
- rhizosphere interactions;
- spatio-temporal pattern
Summary
1. Plant–microbe competition for available nitrogen (N) has been suggested to be an important mechanism controlling N limitation of plants in a variety of ecosystems. However, spatio-temporal patterns of competition between plants and microbes for soil N remain unclear.
2. Short-term 15N tracer experiments were conducted during a growing season (July, August and September) in an alpine meadow on the Tibetan Plateau to unravel spatio-temporal patterns of plant–microbe competition for NH4+ and NO3−.
3. Alpine plants were poorer competitors than soil microorganisms for inorganic N in July compared with August and September. Occupation of soil volume by roots and root density (high in August and September) played a greater role in plant–microbe competition than air temperature or precipitation (high in July).
4. In topsoils (0–5 cm, highest root density), alpine plants effectively competed with soil microorganisms for N and showed a preference for 15NO3−, while soil microorganisms that preferentially took up 15NH4+ out-competed plants below 5 cm soil depth (lower root density). Competition between plants and soil microorganisms for inorganic N strongly depended on root density (P < 0.0001, R2 = 0.93, exponential decay model).
5. Synthesis. Plant–microbe competition for inorganic N showed a clear spatio-temporal pattern in alpine meadows depending on (i) root density and therefore soil depth, (ii) inorganic N form, and (iii) different periods during the growing season. These findings have important implications for our understanding of above-ground–below-ground interactions and plant–microbial competition for available N.