Ten years of defoliation data for six tree species of the systemtic forest condition monitoring network have been correlated with site-specific estimations of various stress factors, both natural and anthropogenic. The stress factors include available and interpolated soil data, interpolated and modelled meteorological data and modelled air pollution and deposition data. Various threshold values were included, e.g. site-specific estimations for the critical deposition levels. The results were highly affected by methodological differences the different countries. On top of this effect, age is an important factor, followed by different natural and anthropogenic stress factors, depending on the tree species.
