Composition of an isolated prairie in central Ontario

A remarkable prairie outlier was recently discovered in central Ontario. The site had about 1.6 ha of open prairie surrounded by 11 ha of Quercus rubra – Pinus strobus savanna. The savanna had a density of about 27 huge, open-grown trees per hectare (11 per acre). The vegetation of the prairie opening comprised four zones ranging from a dry sand barrens to a mesic to wet-mesic prairie arrayed on a gentle slope. The major dominants overall were Sorghastrum nutans, Andropogon scoparius, Danthonia spicata, Lespedeza capitata, Desmodium canadense, Aster azureus, Monarda fistulosa, Solidago nemoralis, Aster sagittifolius, Equisetum hyemale, Car ex rugosperma, and Panicum linearifolium. The site had a rich flora of 115 species, of which more than one-third were listed as prevalent or modal species of Wisconsin prairies and related communities, occurring more than 800 km to the west. In addition, about 15% of the species in the prairie opening were regionally rare and three, Carex richardsonii, Lespedeza intermedia, and Scirpus clintonii, were considered rare in Ontario.