5 - The Mid-Appalachian Shale Barrens

Summary

Introduction

Shale barrens have been a source of fascination to naturalists for the past one hundred years. In the late 19th and early 20th century, botanists noticed sites in the Middle Appalachians supporting an unusual herbaceous flora distinct from the surrounding eastern deciduous forest. Steele (1911) formally introduced shale barren communities to botanists with the following passage:

Several of the species considered are inhabitants of a type of land widely distributed through the mountains of middle Virginia which might well be denominated “shale barrens.” … The barrenness is perhaps largely due to the constant washing away of fine particles of soil, but in some cases it seems as if it must be chargeable to chemical composition. … The variety of plant life is very considerable and together with many plants well known on other substrata, these barrens possess a number peculiar unto themselves.

Thus, the first description delineated shale barren communities on the basis of substrate and presence of a unique flora. In addition, Steele (1911) speculated that in at least some cases soil chemistry must be a factor creating barrens. According to Platt (1951), a surface layer of rock fragments and its rapid erosion are important in maintaining shale barrens. Therefore, it is the structural characteristics of the ground surface and root zone that set shale barren communities apart from the surrounding sandstone ridges and limestone valleys.

Nevertheless, soil features alone are not adequate to delineate a shale barren community.