MECHANISMS INHIBITING THE FOREST DEVELOPMENT OF HISTORIC CHARCOAL HEARTHS IN SOUTHEASTERN PENNSYLVANIA

Charcoal production associated with the iron industry had a pervasive influence on forests during the 17th and 18th centuries in the mid-Atl antic region of the eastern United States. In a recent study we report ed the altered forest composition and soil properties on historic char coal hearths in southeastern Pennsylvania. In this study, additional e xperimental results describe potential past and present mechanisms tha t may inhibit forest development. Nyssa sylvatica Marsh. wood samples taken from the first 15 years of growth on hearth sites contained roug hly half the amount of P and Mn and nearly double the amount of K and Na relative to wood produced on nonhearth sites in the same period, co nsistent with initial pH elevation following hearth abandonment in 188 3. In the greenhouse, Quercus alba L. and Quercus rubra L. showed a si gnificant growth depression in hearth soil. When the proportion of cha rcoal soil varied from 0 to 100%, several growth parameters of e. rubr a declined significantly with increasing charcoal soil content. In sit u foliar nutrient concentrations of Vaccinium corymbosum L. and Quercu s velutina Lam. were significantly different in P K, Ca, Mg, Mn, Fe, N a, and Cu on hearth versus nonhearth plots. The present inhibition of hearth regeneration appears to be the result of persistent differences in soil nutrient availability after more than a century.