Trace element concentrations in epiphytic lichens and bark substrate

The relations were studied between concentrations of 20 trace elements in epiphytic lichens and in the substrate (bark). The bark was separated into two fractions: a 2 mm thick outer layer and the inner layer, not exposed directly to the atmosphere. For most elements a significant correlation was found between the concentrations in the lichen and the concentrations in the outer and inner bark. In general the element concentrations in the inner bark were appreciably lower than those in the outer bark and lichen. For some elements, including Zn and Cd, the concentrations in the inner bark were relatively high, indicating that for those elements the possibility of uptake from the substrate has to be seriously considered.