Human Impacts on Tree‐Ring Growth Reconstructed from Stable Isotopes

Abstract

Publisher Summary Carbon and oxygen isotope ratios in tree rings have been widely applied for the reconstruction of climatic conditions. The carbon isotope ratio is sensitive to warm and dry conditions and enables the retrieval of information on past temperature and precipitation variations during the growing period. The oxygen isotope ratio in tree rings reflects the oxygen isotope ratio of precipitation and is sensitive to temperature, humidity, and the atmospheric circulation patterns. Beside these climatic factors, however, the response of the trees to other environmental conditions must also be considered. Global change does influence the growth patterns of forest trees mainly by changing three parameters, namely climate, CO2, and air pollution. In this chapter, the potential of the combined analysis of different stable isotope ratios is explored to improve our knowledge of tree response to the changes of environmental conditions that occurred in the past two centuries. This chapter is divided into three main parts: (1) carbon isotopes and water-use efficiency reconstructed from tree rings, referring to the effect of increasing atmospheric CO 2 , (2) description of a conceptual model for the combined analysis of δ 13 C and δ 18 O, and (3) a case study with the application of the findings in (1) and (2) to assess local environmental impacts on trees growing near a motorway, using also the analysis of δ 15 N.