On the13C record in tree rings. Part II. Registration of microenvironmental CO2and anomalous pollution effect

Abstract

¹³C data on two sets of Eifel (Germany) trees are presented, which demonstrate severe non-temperature environmental influences disturbing the normal trend of data in this century. For five isolated trees exposed during the last 25 years to higher than normal CO₂ content and other pollution gases, an unexpected increase in ¹³C values has been found, which is explained as pollution effect altering the photosynthetic CO₂ fixation. For five other formerly forest trees of the same location, increasing ¹³C values during the youth stage have been observed, which later became adapted to the normal trend with clearing of their habitat. The ¹³C record for both sets of trees is similar at time periods of similar atmospheric environment. Ring width data of the trees and pollution experiments on barley confirm the observed effects. DOI: 10.1111/j.2153-3490.1979.tb00909.x