Mechanisms of Plant Competition
Microbial mediation of plant competition and community structure
Article first published online: 15 OCT 2012
© 2012 The Authors. Functional Ecology © 2012 British Ecological Society
Special Issue: MECHANISMS OF PLANT COMPETITION
Volume 27, Issue 4, pages 865–875, August 2013
How to Cite
Hodge, A., Fitter, A. H. (2013), Microbial mediation of plant competition and community structure. Functional Ecology, 27: 865–875. doi: 10.1111/1365-2435.12002
- Issue published online: 24 JUL 2013
- Article first published online: 15 OCT 2012
- Manuscript Accepted: 30 AUG 2012
- Manuscript Received: 20 APR 2012
- arbuscular mycorrhizal fungi;
- plant–microbial interactions;
- plant–soil feedbacks;
- soil microorganisms;
- The drivers behind plant competition and diversity have long been debated, and there is acceptance that soil micro-organisms may act as key drivers in plant interactions and community structure. The evidence for a microbial role in shaping plant interactions and communities will be considered here with emphasis on symbionts and pathogens.
- Microbial populations are themselves strongly influenced by the plant community via the ‘rhizosphere’ effect. The rhizosphere community includes microbes both beneficial and detrimental to the plant. Both the ability of plants to cultivate different rhizosphere microbial populations and the resulting impact upon other plant species have largely been studied via ‘plant–soil’ feedback studies, a proxy necessitated by the fact the majority of soil micro-organisms are unculturable, but which nevertheless has rarely been used in conjunction with modern techniques to identify and quantify the micro-organisms involved.
- Both microbial symbionts and pathogens can affect plant diversity and productivity, but the direct evidence for impacts on competitive interactions is surprisingly scarce. Evidence comes from biological invasions, the unintentional introduction of microbial pathogens to native plant communities and manipulative experiments under both field and controlled conditions. Pathogens generally have direct effects on plants, reducing their growth and so rendering them less competitive, whereas other symbionts may act by altering the availability of resources, with more subtle effects on competitive interactions.
- Some of the best evidence for indirect effects comes from studies on arbuscular mycorrhizal (AM) fungi. New developments in our understanding of nutrient exchange in the arbuscular mycorrhizal symbiosis emphasize the need to view the fungal partners not as mere extensions of the plant. The suggestion that AM fungi may act to share resources among connected plants however remains to be proved.
- Although plant competitive interactions can be driven by key microbial groups including symbionts and pathogens, knowledge gaps in the basic biology of these micro-organisms has hindered a full mechanistic understanding of these processes. If ecologists now embrace new technologies, significant advances in this area should be forthcoming.