Horton, Thomas R. , Parker, V. Thomas , O'Brien, Michael J. .
Ectomycorrhizal networks in plant communities: a Gleasonian point of view.
An ectomycorrhizal (EM) network in its simplest form is a single fungal individual inhabiting a volume of soil and colonizing plant roots. However, EM fungi connect multiple plant species when their roots intermingle and the plants are colonized by multiple fungal species. It is tempting to view the mycorrhizal network as part of a Clementsian superorganism with the fungal species in a network being redundant physical extensions of the roots that translocate nutrients freely between plants. But each fungal species brings with it unique capabilities for accessing and translocating soil nutrients. For instance, some EM fungi are particularly abundant in sites with low nitrogen (N) availability, perhaps an indication of a specific role these fungi play in acquiring and translocating recalcitrant N to their host plants. Other fungi may be more abundant in high N availability sites and these may play more of a role in acquiring and translocating phosphorus, calcium, etc. These examples highlight extremes along an N availability gradient, but microsite heterogeneity of most nutrients in a stand probably drives similar patterns at small scales. In addition, fungi have evolved mechanisms for recognizing and preventing fusion of non-self tissue, and as a result, individual networks maintain autonomy. An EM network is therefore best viewed with a Gleasonian individualistic concept with the fungi being part of a complex system of independent networks simultaneously competing for soil nutrients and root tips (carbon). This view suggests that plant competition for soil nutrients is not a function of direct competition between plants. Instead, it is a combination of competition among fungi for nutrients, variations in compatibility between fungal individuals and their colonized plant hosts, and variation in carbon flow to fungi among plants.
Log in to add this item to your schedule
1 - SUNY College of Environmental Science and Forestry, Environmental and Forest Biology, 1 Forestry Dr., Syracuse, New York, 13210, USA
2 - San Francisco State University, Department of Biology, 1600 Holloway Avenue, San Francisco, California, 94132
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Wasatch A/Cliff Lodge - Level C
Date: Wednesday, July 29th, 2009
Time: 4:30 PM