Wednesday Filler: Eastern Great Lakes Savannas

When one thinks of pre-contact southern Michigan, northwestern Ohio, and southwestern Ontario, extensive forests usually come to mind.  While the regions are both heavily developed and otherwise farmed twice over these days, patches of remaining wild land usually have deciduous forests growing on them.  For the most part, trees would have been in great abundance.  A large canopy of maples, beeches, oaks, ashes, and the odd non-riparian cottonwood would have been pierced with extremely tall Eastern White Pine (Pinus Strobus) as well as Tulip Trees (Liriodendron Tulipifera) that would often nearly reach the height of the pines.  Along rivers and in swamps, ashes, cottonwoods, willows, and other such trees would dominate, with much of Detroit once being covered in lush black ash forests.  In certain areas, however, drier, open conditions prevailed.  The last glacial period dumped a lot of sand in the Great Lakes areas, especially on the margins of the great melt-water predecessors of our present bodies of water.

Case in point: The dunes of the shores of ancient Lake Maumee, just west of Toledo.  While much of the ancient shoreline is pretty much indistinguishable under modern development and farms, Oak Openings Preserve, run by Toledo metroparks, has managed to preserve and restore some oak savanna.

Note: That is NOT an abandoned field!  As you can see, lands that in general had more in common with eastern forests than the prairies of the Midwest had (and have, thanks to such places as this) a little bit of both worlds.  Sand, which is not very good at holding moisture, conspired with under-story fires that would burn through the area frequently, at least every few decades and at most annually.  This would result in areas of open prairie spread through mature trees, usually oaks and junipers (though I also suspect pines) which could handle the drier conditions and had some degree of resistance to ground fires.  These pockets of grass and isolated trees would have been surrounded by mixed-forests.  The sort of scene presented above would have been much more common back in the day.  In fact, Oakland county in Michigan is so named because of, you guessed it, its grand oak trees that once grew unfettered and broad in the grass.  Swing by in the next few days to see more of such places.