PARENT SESSION
Symposium #5: Sustaining and restoring our soil.
Sponsored by ESA Soil Ecology Section
Organized by: S.M. Adl. and S. Morris.
Monday, August 6, 2001. 1:00 PM to 4:50 PM. Madison Ballroom A

Arbuscular mycorrhizae and restoration of disturbed soils: structure of hyphae and non-nutritional roles.

Allen, Michael¹, Querejeta, Ignacio¹, Egerton-Warburton, Louise¹, Allen, Edith¹, ¹

ABSTRACT- Arbuscular mycorrhizae (AM) are known to promote establishment of desirable plant species when restoring disturbed sites. The focus on such studies has focused largely on the role of these fungi in acquiring nutrients and water under stress conditions for individual plants. However, AM are more than simply tubes extending out from roots. Dispersal of the AM fungi depends on the vector available. Animals preferentially disperse those forming sporocarps. However, wind entrains and disperses small spores in open soils. After initiation, the AM hyphae grow out from a point forming a mycelium. Hyphal lengths range from a few cm/g up to several m. This mycelium connects multiple plants and holds a matrix of roots and soil particles together. Hyphae of AM fungi also form glomalin, a sticky glycoprotein that binds soil particles into aggregates. Up to 25% of developing organic matter may consist of this group of compounds. During dry periods, deep water is taken up by roots and dispersed out through mycorrhizal hyphae into the surrounding surface soil. This moisture is adequate for nutrient cycling to continue even when surface soils are extremely dry. Differing species of AM fungi and plants have different preferences. Plant performance appears to be affected by the species of AM fungi. AM fungi also respond to differing nutritional conditions. Taken together, AM form a critical group of organisms in the restoration of virtually all terrestrial ecosystems.

KEY WORDS: restoration, arbuscular mycorrhizae, soils