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. 2013 May 22;8(5):e64177. doi: 10.1371/journal.pone.0064177

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© 2013 Niemiller, Zigler

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.

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(a) Ecoregions of Tennessee [following 79]. The eight Level III ecoregions are labeled and Level IV subdivisions of these ecoregions are individually colored with color themes (e.g., oranges, blues, and greens) corresponding to the Level III ecoregions. (b) Distribution of 9517 georeferenced caves and (c) 661 caves with at least one troglobiont recorded in Tennessee overlaid onto ecoregions. Cave and karst regions occur in six Level III ecoregions with the greatest density of caves in the Interior Plateau, Southwestern Appalachians, and Ridge and Valley. The majority of caves occur in exposed geological strata along escarpments marking the transition between ecoregions. County boundaries are also highlighted.