Reply to Schaberg et al.: applying stable isotope analyses to examine the influence of acid deposition on Juniperus virginiana.

Abstract

Our conclusion that a Juniperus virginiana stand in the central Appalachian Mountains is recovering from decades of acid deposition was based on tree ring carbon isotope ratios (δ13C) that show: (i) close correspondence between the timing of changes in direction of δ13C with declines in SO2 emissions occurring after the Clean Air Act; (ii) close similarities between patterns of δ13C after 1980 and during the 1930s Great Depression when SO2 emissions were reduced; and (iii) support of our hypothesis that stomatal conductance would increase after the Clean Air Act if trees were recovering from acid deposition (1). The issues outlined …