Vesicular – arbuscular mycorrhizae in prairie pothole wetland vegetation in Iowa and North Dakota

Vesicular–arbuscular mycorrhizae (VAM) fungal colonization was measured in June and August 1993 for 19 plant species in several vegetation zones in three wetlands in central Iowa and in three wetlands in North Dakota, U.S.A. Percent VAM fungal colonization in all the plants sampled varied greatly with species, ranging from 0.2 to 52.1% (mean = 13, SE = 2.4) in Iowan wetlands and 7.3 to 71.8% (mean = 32, SE = 4.7) in North Dakotan wetlands. The Iowan wetlands had more fertile soils (higher organic matter, higher phosphorus, and lower pH) than the North Dakotan wetlands. Soil salinity was higher in the North Dakotan wetlands. A principal components analysis of environmental factors (soil water matric potential, soil pH, available soil phosphorus, soil specific conductance, and season) indicated that when data for all plant species were pooled, there were only three significant components: location (which reflected differences between Iowa and North Dakota in soil pH, phosphorus, specific conductance, and season), vegetation zone (low prairie, wet meadow, shallow emergent), and soil matric potential. Multiple regression analysis of these principal components and plant species as independent variables and percent VAM fungal colonization as the dependent variable were performed. Regression analyses were also done with VAM fungal colonization as the independent variable and the principal components as the dependent variables on three individual species, Poa pratensis, Spartina pectinata, and Scirpus acutus, which are common to both geographic regions. For the pooled plant species, only plant species and the location principal component were statistically significant. For Poa pratensis, Spartina pectinata, and Scirpus acutus, only the first principal component was statistically significant. The results of this study are consistent with previous studies that suggest plant host species, soil phosphorus, and soil pH influence VAM fungal colonization. Because this study was done during an exceptionally wet year, seasonal changes in mycorrhizal colonization caused by a seasonal decline in soil moisture did not occur as predicted. Keywords: vesicular–arbuscular mycorrhizae, wetland vegetation, environmental gradients, Iowa, North Dakota.