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Prairie Grasses

Past and Potential for Ontario's Natural Heritage - Page 2

Tallgrass communities, composed of prairies and savannas, are ecological communities native to central North America, including extreme southern Manitoba and southern Ontario (see map in Packard et al. 1997). Prairies are open, generally treeless communities dominated by grasses such as big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparius), and Indian grass (Sorghastrum nutans), along with many other native graminoids and native wildflowers, also referred to as forbs (Bakowsky 1993). Savannas are communities dominated by both prairie grasses and open-grown oak trees, such as black oak (Quercus velutina), white oak (Q. alba) and bur oak (Q. macrocarpa) (Bakowsky 1993).

Historically, tallgrass prairie and savanna covered vast expanses of eastern central North America (see map in Packard et al. 1997), including a north-eastward projection through Illinois and into southern Ontario, known as the "prairie peninsula." Most of the original prairie has been destroyed through conversion to farmland and urbanization. Of the approximately 90 million hectares that is estimated to have occurred historically (W. Ostlie, pers. comm.; W. Bakowsky, pers. comm; Joyce and Morgan 1989; Nuzzo 1986; Watts 1969), it is likely that no more than four percent (W. Ostlie, pers. comm.) and perhaps as little as one percent (Kline 1997) remains. In Ontario, the prairie peninsula may more accurately be described as an archipelago, since historically tallgrass communities dotted the landscape throughout the southern part of the province (Goodban et al. in press; Bakowsky and Riley 1994; Catling et al. 1992; Szeicz and MacDonald 1991) . Figure 1 (246K) shows the historical extent of large areas of tallgrass communities, as determined from historic surveyor notes. This area totaling approximately 825 km2 represents the minimum historic area of tallgrass in southern Ontario; smaller areas would doubtless have been interspersed throughout the region (W. Bakowsky, pers. comm; A. Woodliffe, pers. comm.). Currently, a mere 21 km2 remains (W. Bakowsky, pers. comm.), mostly in small, isolated remnants (Figure 2, 73K).

Page 1 2 3 4 5 6 7 8 9 10 References Appendix 1

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Page design © 1999 T. A. Dickinson; essay text and illustrations © 1998 Lindsay Rodger except as noted.
Please send your comments to tim.dickinson@utoronto.ca; last updated 7-May-99

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