Table 3. Biological data used to create species richness maps. Taxon Survey method Number of sites Reference Agriculture Introduced grassland Forest Prairie Vascular plants 0.22 x 0.5 m frame plots 0 3 0 12 (Hanson et al. 2008) Vascular plants 2 x 20 m transects 3 6 12 3 (Pocewicz 2006) Butterflies Variable distance transects 3 6 12 3 (Pocewicz 2006) Butterflies Pollard transects 3 4 7 0 (C. Looney, unpublished manuscript)