PARENT SESSION
Oral Session 15: Soil Ecology I: Mycorrhizal Communities.
Presiding: V Borowicz and X He
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 137.

Phosphorus acquisition by old field perennials: The role of arbuscular mycorrhizal fungi.

Reynolds, Heather^*,1, Vogelsang, Keith¹, Hartley, Anne², Bever, James¹, Schultz, Peggy¹, ¹ Indiana University, Bloomington, IN² Florida International University, Miami, FL

ABSTRACT- Can arbuscular mycorrhizal fungi promote phosphorus (P) partitioning of plant hosts, thus providing one mechanism for the maintenance of plant community diversity? We asked whether AMF improved the ability of old field perennials to grow on a range of P sources, and whether AMF facilitated differential performance of plant species on different P sources (P niche partitioning). We manipulated form of P (control versus different inorganic and organic sources) and AM fungal species (control versus four individual AMF species or an AMF community) for five old field perennials grown in a greenhouse under P-limiting conditions. Based on biomass after four months of growth, we found that effects of AMF varied from parasitic to mutualistic depending on plant species, AMF species, and P source (significant plant x fungus x P interaction). We found no evidence for AMF-facilitated P niche partitioning, rather the right AMF species appeared to improve plant access to all forms of P, and some plant species were relatively insensitive to AMF.

Key words: AMF, community diversity, old field perennials, phosphorus partitioning