Appalachian Balds–Relic landscapes of the Ice Age

Appalachian balds may be relic landscapes of the Ice Age.  Scientists theorize that they formed during the coldest stages of the Wisconsinian Ice Age when wind, cold, and aridity combined to kill trees on the tops of high elevations in the southern Appalachians.    Grass, however, was able to colonize and grow in this habitat.  Grazing animals such as mammoths, bison, musk-oxen, horses, elk, fugitive deer, caribou, and  llamas kept trees from regrowing by trampling the ground and destroying tree saplings.   The grass, itself, once established, prevented trees from re-colonizing the area.  The root systems grow thickly and the grass surface stops tree seeds from even coming into contact with the soil.

Relic plants growing on Appalachian balds are disjunct species that today are more commonly found in Canada, New England, and the upper midwest; and they’re absent from the lowlands surrounding the grassy balds.  Mountain oat grass is the dominant species, but there are many more.

After the extinction of the megafauna, bison and elk remained and along with Indian-set fires helped maintain the balds until English settlement.  The colonists used the land for grazing livestock, but at the beginning the the 20th century, farming here became uneconomical, the land was abandoned, and trees have started to encroach upon the land.  The U.S. forest service is trying to maintain these unique ecosystems with goat grazing and controlled burns, but many already have been lost to reforestation.

Curiously, mature hemlock forests grow right next to the balds–a stunningly different environment.  These shady habitats have a largely bare undergrowth, though ferns and moss occur in patches.

For my book I took a number of pictures  at the Roan Mountain bald which is on the border of North Carolina and Tennessee.   One of these is on the back cover of the book.  I think they’re really nice pictures, though I’m no professional photographer.  Unfortunately, the ones I have on the inside of my book had to be converted to black and white so the book would be affordable, but here I can post them in color on the internet for free.

 These are beautiful landscapes and must resemble what much of Georgia’s Pleistocene looked like, minus the extinct and extirpated mammals.  Georgia likely had lots of prairies and savannahs with a few scattered trees.  Nevertheless, Georgia was still mostly forested, according to pollen studies.  There were probably open parkland woods, closed canopy forests along streamsides and rivers, and hammocks of trees surrounded by meadows and prairies.

The scattered trees in the photos are hemlock and white pine.

The first photo is of a heath thicket.  Some balds are covered with shrubs rather than grass.  The last photo is of a hemlock forest.  The grassy balds are the middle three pictures.

This is a heath thicket.  Some balds are covered with shrubs rather than grass.Note the mountain oat grass in the foreground.


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