Abundance and distribution of vascular plants and vesicular-arbuscular mycorrhizal (VAM) fungi across a soil moisture-nutrient gradient were studied at a single site. Vegetation on the site varied from a dry mesic paririe dominated by little bluestem (Schizachyrium scoparium) to emergent aquatic vegetation dominated by cattail (Typha latifolia) and water smartweed (Polygonum hydropiperoides). Plant cover, VAM spore abundance, plant species richness, and number of VAM fungi represented as spores, had significant positive correlations with each other and with percent organic matter. The plant and VAM spore variables had significant negative correlations with soil pH and available Ca, Mg, P and gravimetric soil moisture. Using stepwise multiple regression, Ca was found to be the best predictor of spore abundance. Test for association between plant species and VAM fungal spores indicated that the spores of Glomus caledonium are associated with plants from dry, nutrient poor sites and spores of gigaspora gigantea are positively associated with plants occurring on the wet, relatively nutrient rich sites. Glomus fasciculatum was the most abundant and widely distributed VAM fungus and it had more positive associations with endophyte hosts than the other VAM fungi. We found no relationship between beta niche breadth of plant species and the presence or absence of mycorrhizal infection. However, our data suggest that some plant species may vary with respect to their infection status depending upon soil moisture conditions that may fluctuate seasonally or annually to favor or hinder VAM associations.

The percentage of vesicular–arbuscular mycorrhizal (VAM) colonization of little bluestem (Schizachyrium scoparium) (Michx.) Nash.) and VAM spore populations in the rhizosphere of little bluestem from four prairie areas in Illinois were studied. At Goose Lake Prairie, a significant positive correlation (r = 0.77, p < 0.01) was found between soil moisture and density of VAM spores, but soil moisture and percent VAM colonization were not significantly correlated at any of its sites. Percentage of VAM colonization tended to be higher at study areas where little bluestem was a dominant species. However, spore numbers and abundance of little bluestem tended to be inversely related. Colonization decreased from May to July at all areas and this trend frequently continued into September. Month of sample collection had no significant effect on spore numbers except at Reavis Hill Prairie. The endophyte isolated at all areas was Glomus fasciculatum (Thaxter sensu Gerd.) Gerd. & Trappe. Other species, such as Gigaspora heterogama (Nicol. & Gerd.) Gerd. & Trappe and Acaulospora laevis Gerd. & Trappe, were more restricted in their distribution.

No abstract

No abstract

No abstract