PARENT SESSION
Poster Session 30: Soil Ecology.
Wednesday, August 4 Presentations from 5:00 PM to 6:30 PM, Exhibit Hall A 1.
The effect of arbuscular mycorrhizae on soil aggregation depends on the interaction between plant and fungal species.
Piotrowski, Jeff*,1, Denich, Tanya 2, Klironomos, John2, Graham, John1, Rillig, Matthias1, 1 University of Montana, Missoula, MT, USA2 University of Guelph, Guelph, ON, Canada
ABSTRACT- The formation of water stable aggregates (WSA) is crucial to preventing soil erosion and in biogeochemical cycling. Soil aggregation is mediated by arbuscular mycorrhizal fungi (AMF) and plant roots; and, as with other functions like phosphorus uptake, specific AMF/plant combinations may control WSA formation. The precise mechanisms of WSA formation via roots and hyphae are unknown, but WSA formation in natural systems is often correlated with root biomass and hyphal lengths. The %WSA, root biomass, and hyphal lengths were measured in a 5 AMF species X 9 plant species full factorial experiment using all material from the same ecosystem. The %WSA varied significantly depending on the symbionts combination, and an interaction between AMF and plant host with respect to %WSA was observed (p<0.0001). Fungi in the Gigasporaceae on average formed more WSA than other AMF (p=0.039); these fungi also promoted lower root biomass (p<0.0005) and had the highest hyphal lengths (p<0.0005). Plants grown with Gigasporaceae fungi did not consistently have the highest %WSA across all hosts though, suggesting physiological controls of aggregate formation through the AMF/ host interaction (beyond biomass). We conclude that the extent of soil aggregate stabilization by AMF and plant hosts depends on the specific combinations of the symbionts, and propose that AMF/ plant combinations could be tailored to manage for greater aggregation in both agricultural and ecosystem restoration.
Key words: soil aggregation, erosion, arbuscular mycorrhizal fungi, plant-fungus interaction