“…Stemflow, i.e. water running down along branches and stem, has been often considered to explain acidification of the stemflow area under beech [17,18,19,15,8,16], more especially in polluted countries [49,48,24,21,43]. Changes in litter quantity and quality under the canopy of trees have been also evoked, more especially the role of bark deposition [50,26,19].…”