Spatio-temporal variations determine plant–microbe competition for inorganic nitrogen in an alpine meadow
Article first published online: 19 JAN 2011
© 2011 The Authors. Journal of Ecology © 2011 British Ecological Society
Journal of Ecology
Volume 99, Issue 2, pages 563–571, March 2011
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
- 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
- 15N tracer;
- alpine Kobresia meadow;
- inorganic N;
- plant–microbe competition;
- plant–soil (below-ground) interactions;
- rhizosphere interactions;
- spatio-temporal pattern
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.