Distribution and biohistory of the endemic flora of the mid-Appalachian shale barrens

Restoration Results for a Maryland Shale Barren after Pignut Hickory Management and a Prescribed Burn

“…High soil surface temperature, which can exceed 508C for several hours with direct sunlight, and low soil moisture levels are believed to severely limit woody seedling survival on mid-Appalachian shale barrens (Platt 1951, Keener 1983, Braunschweig et al 1999. In an Illinois shale barren, McCall and Gibson (1999) reported a noticeable shift in mesic to xeric vegetation and seedling composition just three years after prescribed burning and the removal of a nearly closed overstory.…”

“…Shale barrens are widely distributed in the Ridge and Valley Province of the mid-Appalachian Highlands along both sides of the Virginia-West Virginia border and through Maryland into south-central Pennsylvania (Core 1940, Keener 1983. Shale barren communities usually occur on steep slopes, typically with west-to-southerly aspects, and at elevations between 300 m and 700 m (Platt 1951, Keener 1983, Braunschweig et al 1999. The types of shale supporting barren communities originated mostly during the Devonian Period of the Paleozoic Era but also during the Ordovician and Silurian Periods (Braunschweig et al 1999).…”

“…The literature is rich in botanical reports especially for near-endemic taxa. A lengthy review of these taxa was provided by Keener (1983), followed with slight modifications by Braunschweig et al (1999). Both reviews concluded that shale barren nearendemics are obligate heliophytes.…”

Analytical Biogeography

“…Endemism is important when the history and origin of a flora are considered (Tolmachev, 1974a;Keener, 1983;Goloskokov, 1984). According to Braun-Blanquet (1923) who studied the origin and development of the flora of the Massif Central in France, "the study and precise interpretation of endemism of a territory constitute the supreme criterion, indispensable for consideration of the origin and age of its plant population.…”

“…Endemics may be relicts or recent. Even then details on life histories, demography, physiology and reactions to competition may be largely lacking (Keener, 1983). Takhtajan (1978) employs endemism at various taxonomic levels from family to species to characterize floristic regions of the world, from his six kingdoms down through 35 regions to 153 provinces.…”