Today’s research on tree-ring analysis is faced with the question whether growth of forests and climatic conditions have changed under anthropogenic emissions during the industrial period. The base for answering this question is as follows:
◦ All tree-rings are absolutely dated. Therefore they can be compared with dated climatological factors. ◦ Genetical and ecological variability within groups of individual trees can be minimized by building mean tree-growth curves, so-called chronologies.
◦ Ecologically defined tree-ring networks allow direct spatial reconstruction of growth patterns and their climatological interpretation.
Based on a modem radiodensitometric technique (Eschbach et al. 1995) of a tree-ring and temperature network (Schweingruber and Briffa 1996) which covers the northern parts of the northern hemisphere, the time period of the past 300 years remains to be interpreted. It is of crucial importance that the time of most intensive industrialization in boreal forests be compared on a long ranging time scale.