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Fig. 3. (a) Ordination of the regional dataset (Principal Component Axes 1 and 2—PC 1 and PC 2; n = 6 for SGS due to three samples from the October 2000 sample date being lost during transport and lab processing; for ARI, two samples occupy almost identical locations on the ordination are therefore represented by one point). Microbial community composition differed among grassland community types, with shortgrass steppe sites (SGS and ARI) located in the first and second quadrants, the tallgrass prairie site (KONZA) located in the third and fourth quadrants, and the mixed grass prairie sites (SVR and HAYS) occurring intermediately in the principal component space between the other two community types. (b) Ordination of the landscape dataset (with the same PC 1 and PC 2 as in Fig. 3a since both datasets were analyzed together in one principal component analysis; n = 3 for uplands at HAYS due to sample loss during transport, and n = 3 for lowlands at KONZA because an outlier data point was excluded from this analysis). Different microbial communities were associated with the different grassland community types and occur in the same general principal component space as in Fig. 3a. Uplands and lowlands also exhibit different microbial communities, with uplands generally higher on the PC 2 axis than lowlands for each site.
