A 200-year paleoecological record of Pinus virginiana, trace metals, sedimentation, and mining disturbance in a Maryland serpentine barren1

Abstract The objective of this study was to provide stratigraphic data that could augment historic and recent ecological information concerning the cause of the 20th century vegetation shift from grassland to pine forest in a central Maryland serpentine barren, and potentially elucidate the role of fire, chromium mining, grazing, and other disturbances on serpentine vegetation. A 46-cm core was extracted from a shallow pond draining the watershed of Chimney Branch, underlain by serpentinite. Core chronostratigraphy was established by identifying two sharp spikes in Cr concentrations correlated with historic Cr mining activity peaks and an abrupt increase in pine needle abundance, when pine populations expanded around the coring site. Pine needle analysis reveals that Pinus virginiana (Virginia pine) has been present within a few meters of the coring site since ca. 1810, 120 years earlier than previously documented. A dearth of charcoal over the 200-yr period indicates there were no major fires at the cori...