The big barrens region of Kentucky and Tennessee: further observations and considerations

A wide variety of landtype associations (sensu Smalley 1980) occurs on the Mississippian limestone karst plain of Kentucky and Tennessee. Thus, although much of this region is in agriculture, it supports a diversity of native plant communities. These include limestone cedar glades (edaphic climax communities on nearly flat areas of limestone bedrock and shallow soil dominated by annual or perennial forbs, annual grasses, cryptogams, or some combination of these); xeric limestone prairies of anthropogenic origin dominated by native perennial grasses and/or forbs; barrens (deep-soil, culturally-derived and maintained grasslands dominated by native perennial grasses); forests of dry, mesic, and wetland sites; and aquatic vegetation of sinkhole ponds. The historical occurrence of extensive areas of grassland interspersed with stunted trees and shrubs ("barrens") on the Kentucky Karst Plain is well documented. Transeau included these Big Barrens on his original (1935) and revised (1956) maps of the Prairie Peninsula, implying that they were formed during the Hypsithermal Interval of the Holocene, and this idea generally has been accepted by plant ecologists and geographers. However, after reviewing the literature, we previously concluded that the Big Barrens came into existence as a result of burning of forests by Native Americans in pre-European settlement times, and thus should not be considered part of Transeau's Prairie Peninsula. Additional evidence from the literature, on paleovegetation, paleoclimate, and plant and animal geography, further confirms our earlier conclusion that the Big Barrens are not an outlier of the Midwestern Tallgrass Prairie.