Natural vegetation and its relationship to the environment of selected abandoned coal surface mines in the Cumberland Mountains of Tennessee

Cluster analysis of species' importance values (IV) based on the sum of relative density and relative basal area revealed the presence of five types in the canopy: Tulip Poplar, Black Locust, Red Maple, Pine-Red Maple-Black Locust and Shortleaf Pine. Discriminant analysis of species' IVs confirmed the integrity of these types. Reciprocal averaging of species' IVs and discriminant analysis of the environmental variables in each type suggested correlation of the canopy vegetation with spoil pH, relief position (bench, crest of spoil bank or outslope) and slope angle measured perpendicular to the contour. Spoil pH is an indicator of nutrient availability and relief and slope angle were assumed to be primarily indicators of spoil moisture availability.

A similar analysis of the understory revealed six types: Blackberry, Catbrier, Red Maple, Red Maple-Blackberry, Red Maple-Liana and Tulip Poplar. Discriminant analysis of environmental variables and reciprocal averaging of species relative densities suggested correlation of the understory to percent canopy closure, spoil pH and available spoil moisture.

Common ground cover species were Acer rubrum, Andropogon virginicus, Aster spp., Eupatorium purpureum, E. rugosum, Helianthus microcephalus, Lonicera japonica, Microstegium vimineum, Panicum spp., Parthenocissus quinquefolia, Rhus radicans, Solidago caesia and S. flaccidifolia. Reciprocal averaging of the ground cover species was hampered by a quadratic relationship between the first and second axis. The resulting arch was removed with detrended correspondence analysis. The sample first axis correlated with spoil pH and the species ordination suggested a response to spoil moisture availability. The second axis remained largely uninterpretable.

Comparison of mine vegetation with the surrounding undisturbed forest was performed by sampling the undisturbed vegetation of six mines (27 400 m² plots). Generally these stands were dominated by Quercus prinus with Q. rubra, Liriodendron tulipifera and Acer rubrum also important. Species reciprocal averaging of the combined mine and undisturbed samples (in presence/absence mode) separated the species which are more shade tolerant and less adapted to long distance dispersal (characteristic of the undisturbed forests) from those which are less shade tolerant and adapted to long distance dispersal (characteristic of the mine vegetation). Generally, the mine vegetation was reflective of the surrounding seed sources available in the undisturbed forest. The effect of local seed sources on the distribution of the species may be important.