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Center for Cedar Glade Studies

Glade Zones

Between areas where there are exposures of solid rock and the Oak-Hickory forests common to middle Tennessee are four transitional zones. (as outlined by Thomas E Hemmerly in Wildflowers of the Central South, 1990)

All glade scholars would consider exposed rock, gravelly glades, and grassy glades to be true “glades.” However, some would also include the xeric limestone prairie and cedar woods.

Zone 1 – Exposed Rock – no soilNo plants Stones River Battlefieldphoto by Nancy Stetten

Zone 2 – Gravelly Glades – 0-2 inches of soilRelatively few organisms grow on gravelly glades. We find cyanobacteria and a small selection of small herbaceous flowering dicots. photo by Jeff Walck

Zone 3 – Grassy Glades – 2-8 inches of soilThis zone is dominated by annual grasses and taller flowering plants. photo by Jeff Walck

Zone 4 – Xeric Limestone Prairie – 8-12 inches of soilThis zone is dominated by perennial grasses, but also has a wide variety of other plants, lichens and mosses.  Stones River Battlefield, Murfreesborophoto by Terri Hogan

Zone 5 – Cedar Woods – >12 inches of soilThis zone is dominated primarily by red cedar, upland privet, coralberry, and aromatic sumac.  Stones River Battlefield, Murfreesborophoto by Nancy Stetten

Zone 6 – Oak-Hickory Forest – >12 inches of soilSpecies of oacks and hickories are primarily found in this zone.

These zones form a continuum on four important variables according to Thomas Hemmerly, in Wildflowers of the Central South, Vanderbilt University, Nashville, 1990. Hemmerly presents the ranges on the continuum in the chart below.

The patterns which these zones make depend on the stratum on which they are located.

Where the glade is located on thinly bedded limestone like the Lebanon Limestone, the zones take a random pattern. This is because the layers of rock are thin and easily fractured. A crack in the rock allows soil to accumulate and provides a foothold for grass, shrubs, or even a cedar tree.

Where the glade is located on thickly bedded limestone like the Ridley Limestone, the zones have a more predictable pattern.

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Middle Tennessee State University
Center for Cedar Glade Studies
Department of Biology 
PO Box 60
Murfreesboro, TN 37132
615.904.8283 (phone for Kim Cleary Sadler)