ALTERED FOREST COMPOSITION AND SOIL PROPERTIES OF HISTORIC CHARCOAL HEARTHS IN SOUTHEASTERN PENNSYLVANIA

This study related age structure and composition of forests in southea stern Pennsylvania to edaphic properties caused by the activities of a local charcoal iron furnace from the late 18th to the late 19th centu ry. Forests surrounding charcoal hearths were harvested on 20- to 30-y ear rotations to supply wood for charcoal production in earthmound kil ns. Charcoal hearths were created by a recurring cycle of disturbance, including the removal of established vegetation, intense heat, and th e deposition of charcoal. Thirty-eight hearths of Hopewell Furnace Nat ional Historic Site were examined to describe differences in vegetatio n relative to surrounding forests that have developed since the cessat ion of charcoal production in 1883. Hearth forests were significantly younger than surrounding forests, with lower tree density and basal ar ea, decreased sapling and shrub abundance, and higher herbaceous cover . Compositional differences on charcoal hearths included decreased imp ortance of several Quercus species and ericaceous shrubs and increased importance of Liriodendran tulipifera L. Results of this study indica ted that the initial effect of charcoal production was the prevention of stump sprouting and a delay in recolonization following disturbance due to extreme soil physical and chemical properties. Failure of hear th seedlings to recruit into larger size classes, age-diameter relatio nships of Liriodendron tulipifera L. trees, and the failure of calcifu ge species to reestablish similar cover on charcoal hearths suggested that unfavorable properties of charcoal soils continue to negatively a ffect long-term productivity. Relative to nonhearth soils, large, sign ificant differences in soil pH, cation exchange capacity, base saturat ion, and exchangeable Ca, Mg, and K indicated that continuing inhibiti on of woody plants on charcoal hearths may be related to alterations i n soil chemistry that have persisted for 110 years.