RHODORA, Vol. 111, No. 945, pp. 21–108, 2009 E Copyright 2009 by the New England Botanical Club SERPENTINE GEOECOLOGY OF EASTERN NORTH AMERICA: A REVIEW NISHANTA RAJAKARUNA College of the Atlantic, 105 Eden Street, Bar Harbor, ME 04609 Current Address: Department of Biological Sciences, One Washington Square, San Jose´ State University, San Jose´, CA 95192-0100 e-mail:
[email protected] TANNER B. HARRIS University of Massachusetts, Fernald Hall, 270 Stockbridge Road, Amherst, MA 01003 EARL B. ALEXANDER 1714 Kasba Street, Concord, CA 94518 ABSTRACT. Serpentine outcrops are model habitats for geoecological studies. While much attention has been paid to serpentine outcrops worldwide, the literature on eastern North American serpentine and associated biota is scant. This review examines the available literature, published and unpublished, on geoecological studies conducted on serpentine in eastern North America, from Newfoundland through Que´bec and New England south to Alabama. Most serpentine outcrops in the region have been mapped, but there have been few intensive mineralogical and pedological investigations. The limited soil analyses available suggest elevated levels of heavy metals such as Ni, near-neutralpH values, and Ca:Mg ratios , 1, characteristic of serpentine soils worldwide. Botanical studies to date have largely focused on floristic surveys and the influence of fire exclusion and grazing on indigenous vegetation. To date, 751 taxa of vascular plants belonging to 92 families have been reported from serpentine outcrops in the region. Two taxa, Agalinis acuta and Schwalbea americana, are federally endangered in the United States while many others are listed as rare, endangered, or imperiled in one or more states or provinces.