Forest Composition and Structure on Glade-forming Limestones in Middle Tennessee

Published:

Dec 2012

Author

David A. Adams

Additional Authors

Jeffrey L. Walck, R. Stephen Howard, Per Milberg

ABSTRACT Within a successional context, the vegetation associated with the cedar glade ecosystem in middle Tennessee develops from bare limestone bedrock to subclimax redcedar, preclimax oak-hickory, and climax mixed hardwood forests. Studies on the composition and structure of forests associated with cedar glade–forming limestones (Lebanon, Ridley) are rare. We sampled the canopy and understory of six forest stands in middle Tennessee on these limestones. Observed number of canopy species was 14–24 across stands; estimated richness was greater by 1–3 species (bootstrap) or 3–6 species (first-order jackknife) than observed richness. With the exception of Ailanthus altissima in one stand, all other canopy species were native. Juniperus virginiana, Fraxinus americana, Carya ovata, and Quercus muehlenbergii were primary canopy components in 4 or 6 stands, and C. glabra, Q. shumardii, Ulmus alata, F. quadrangulata, Q. alba, and Q. velutina in 2–3 stands. When we included stands from a previously published study (most on the non-glade Carters Limestone) with our data, a principal components analysis identified three groups with the axes approximating a moisturebedrock gradient and a time-successional gradient. An examination of regeneration in our stands predicts that (1) mesophytes and/or fire-sensitive species (Acer saccharum, Fraxinus spp., Celtis spp.) will increase and (2) xerophytes and/or fire-adapted species (Quercus spp., Carya spp.) will decrease. Altogether, our results strongly suggest that the oak-hickory stage shown in successional outlines of vegetation development associated with the cedar glade ecosystem may not occur in its current state in the future.

Keywords

Cedar glades, Central Basin, maple, oak-hickory forest, regeneration, species accumulation curves. glades