Modeling the response of soil and surface waters in the Adirondack and Catskill regions of New York to changes in atmospheric deposition and historical land disturbance

In this study, an integrated biogeochemical model (PnET-BGC) was used to evaluate the response of five forest ecosystems in the Adirondack and Catskill regions of New York to changes in atmospheric deposition and land disturbance. Model simulations showed that over the past 150 years, acidic deposition caused depletion of nutrient base cations (i.e., Ca²⁺, Mg²⁺), enhanced mobilization of aluminum (Al) and accumulation of sulfur (S) within the soil. Model simulations also showed that acidic deposition resulted in elevated concentrations of inorganic monomeric Al, sulfate (SO₄^2-) and nitrate (NO₃^-), and low values of pH and acid neutralizing capacity (ANC) in surface waters. Model results also indicated that forest harvests resulted in enhanced leaching of base cations and NO ₃^- over the short term (∼5yr). Over the long term, forest harvesting influences surface water NO₃^- and base cation concentrations, and pH and ANC. The model was also used to predict the responses of these forest ecosystems to three emission control scenarios. Model simulations indicated that under the 1990 Clean Air Act Amendment, these ecosystems showed little recovery after 2010. Additional reductions in strong acid inputs will result in significant benefits in terms of recovery from acidification. Under an aggressive control scenario, surface water ANC of these ecosystems was predicted to recover at rates ranging from 0.28 to 0.58μeql^-1yr^-1.