PARENT SESSION
Poster Session #25: Mycorrhizal Fungi and Root Processes.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Vertical distribution of arbuscular mycorrhizae associated with mesquite.

Garrett, Laura¹, Griffith, Jennifer¹, Aniskoff, Lara^*,1, Glatt, Batsheva¹, Chern, Daniel¹, Titus, Jonathan¹, ¹ Columbia University's Biosphere 2 Center, Oracle, AZ

ABSTRACT- Mesquite (Prosopis glandulosa), an obligately arbuscular mycorrhizal (AM) species, is the dominant tree of the Apacherian savanna of southeast Arizona and is characterized by a very deep root system. A corn bioassay was used to examine the mycorrhizal inoculum potential (MIP), or the amount of AM propagules, at 10 cm depth intervals in 1 m deep soil pits adjacent to mesquite trees across two seasons. MIP decreased with depth from a high of 29% in the surface soil to a low of 5% in the caliche layer. Spore densities also decreased with depth from a high of 5 spores/10cm³ soil in the surface soil to a low of 1 spore/10cm³ soil in the caliche layer. MIP and spore densities increased below the caliche and also increased from spring to fall. There was a non-significant decrease in AM colonization of mesquite roots with depth. Thus, AM propagule density, colonization and spore abundance change with depth in arid systems with a decrease from the surface to the caliche layer and an increase in the soil below the caliche layer.

KEY WORDS: arbuscular mycorrhizae, mesquite, Apacherian savanna, Sonoran Desert