Forest Soil Cation Dynamics and Increases in Carbon on the Allegheny Plateau, PA, USA Following a Period of Strongly Declining Acid Deposition

Reductions in exchangeable calcium and magnesium increase aluminum concentrations have been shown soils impacted by acid deposition, including at four sites on the Allegheny Plateau, PA, USA, sampled 1967 1997 during a period of peak deposition. We repeated sampling these 2017 to evaluate changes more recent when there has strong decline The uppermost horizons, Oa A horizons where humified organic matter transitions mineral soil, were thicker, had higher carbon magnesium, lower compared 1997, approximating values measured 1967. Below Oa/A soil chemistry was similar results, with some reduction Ca measurements. These results suggest recovery base cation–aluminum balance surface may indicate mobilization increased efficiency vegetation recycling nutrients decreased anion concentrations. are consistent partial from However, also be affected coincident increases temperature moisture.