Erratum: The case for prairie restoration
The "sea of grass" actually had many islands of trees here and there, proving once again that nothing in the midwest is as simple as it looks. There's a bit of one such grove still thriving down in Urbana, proving once again that I probably really ought to be working at U of I. (Sigh.) If only it weren't so depressingly flat down there. Yes, it's flat up here too, but at least there's a big lake to look at and impressive sand dunes not too far away. But that ecosystem is a whole different story for another day.
From Environmental Almanac:
Urbana’s Ancient Oaks Provide Living Link to the Big Grove
"When we think about the landscape of central Illinois prior to European settlement we tend to think 'prairie,' but prairie is not the whole story. Groves of trees intruded on the grasslands here and there, especially on the eastern edges of rivers and streams, which created natural breaks to prairie fires driven by winds from the west.
"Such groves were dominated by fire-resistant species of oak, and interspersed with hickory, ash, walnut, sugar maple and linden trees as well."