PARENT SESSION
Oral Session #91: Mutualisms -- Facultative, conditional, and complex.
Presiding: W. Wilson
Thursday, August 8. 1:00 PM to 3:45 PM. Cochise Meeting Room, TCC.
Terrestrial vertebrates promote arbuscular mycorrhizal fungal diversity and inoculum potential in a rainforest soil.
Gehring, Catherine*,1, Wolf, Julie1, Theimer, Tad1, 1 Northern Arizona University, Flagstaff, Arizona
ABSTRACT- Although vertebrates disperse mycorrhizal fungal spores, little is known about how important this dispersal is to plants in natural systems. We examined whether terrestrial vertebrates affected arbuscular mycorrhizal spore communities and the inoculum potential of a rainforest soil by comparing 13 field plots (6.5 X 7m) where terrestrial vertebrates had been excluded for three years to 13 adjacent control plots. We extracted spores from soil using sucrose density gradient centrifugation and assayed mycorrhizal inoculum potential by growing seedlings of corn and a rainforest tree (Flindersia brayleana) in replicate intact soil cores from exclosure and control plots. Control plots had significantly higher spore abundance, species richness and diversity than exclosure plots. Community analyses using non-parametric multi-response methods also demonstrated that spore community composition differed significantly between exclosure and control plots. These differences in spore communities were associated with significant differences in mycorrhizal inoculum potential. In both seedling species, seedlings grown in control soil cores had significantly higher mycorrhizal colonization than seedlings grown in exclosure soil cores. Corn seedlings in control cores were also significantly larger. This study is the first to demonstrate that exclusion of terrestrial vertebrates alters the mycorrhizal inoculum potential of rainforest soil and suggests that loss of vertebrates could alter rates of mycorrhizal colonization with consequences for the dependent community and ecosystem properties.
KEY WORDS: terrestrial vertebrate, spore dispersal, arbuscular mycorrhizae, rainforest