CHAID Models on boundary conditions of metal accumulation in mosses collected in Germany in 1990, 1995 and 2000

The European heavy metals in mosses surveys allow mapping the metal accumulation in mosses indicating atmospheric deposition. Yet, there is still great uncertainty on how local and regional phenomena influence the atmospheric metal bioaccumulation. Therefore, the presented study aims at ranking factors that affect the spatial patterns of the metal concentrations in the mosses. Applying chi-square automatic interaction detection (CHAID) to the German moss measurements and related sampling site-specific descriptions taken from the surveys in 1990, 1995 and 2000 and supplementary land cover data, the spatial variation in metal concentrations in mosses were proved to depend mostly on different moss species, canopy drip and distance to the sea. Most of these findings could be corroborated by classification tree analyses on the same data as presented in another study. The results of both the studies should be verified by applying the same methodology using additional emission and deposition data and monitoring information from other countries participating in the UNECE moss surveys.