Tree-ring width and δ13C records of industrial stress and recovery in Pennsylvania and New Jersey forests: Implications for CO2 uptake by temperate forests

We present dendrochronological records of tree-ring width and delta C-13 values for representative living trees (ages of 70 to 230 years) in Pennsylvania and New Jersey to investigate the ecological responses to industrial pollution and recent management and their effects on carbon storage in the temperate forests. Chestnut oak, red oak and cedar trees consistently show elevated delta C-13 levels (1.3 to 4.1 parts per thousand higher than unpolluted normal values) during the period of intense pollution from similar to 1900 to similar to 1970, indicating significant industrially induced physiological stress on the trees. Since similar to 1970, oak and cedar trees have shown remarkable increase in growth rates and rapid decrease of 0.6 to 2.5 parts per thousand in delta C-13 values, indicating the recovery of trees corresponding to the implementation of the Clean Air Act in the early 1970s. The growth enhancement since 1970 has resulted in an increase in biomass of similar to 26% in cedar trees and similar to 66% in oak trees, suggesting that air-cleaning efforts have made a significant contribution to CO2 uptake by the temperate forests, at least in the northeastern USA. (C) 2010 Elsevier B.V. All rights reserved.