PARENT SESSION
Poster Session # 9: Herbivory.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Survey of the effects of ungulate grazing on the relationship between VAM fungi and plants in Yellowstone National Park.
Murray, Tanya1, 1 Syracuse University, Syracuse, NY
ABSTRACT- Comprehensive understanding of vesicular-arbuscular mycorrhizae in systems that support grazers may offer valuable insight to the mechanisms by which plants respond to grazing pressure. A survey of seven sites in Yellowstone National Park compares the species diversity and structural characteristics of VAM fungi collected inside and outside long term grazing exclosures. These sites are located in the northern range of YNP where ungulates (Bison bison and Cervus elaphus) graze during the winter months. The sites vary in slope and moisture from dry upland to wet lowland soils. Data obtained from random samples are compared to data from dominant plant samples to determine landscape and grazing influences on mycorrhizal composition and structural characteristics. For each site VAM species diversity is determined from spore density and diversity. Plant benefit from the mycorrhizal association is assessed using a supplier ratio based on the relative investment in arbuscules vs. other components of internal colonization. Finally, mechanisms of mycorrhizal function with and without grazing pressure is analyzed by comparing internal and extramatrical hyphal abundance from soil and root samples collected inside and outside grazing exclosures.
Key words: VAM, herbivory, mycorrhizal hyphae, spore diversity