Litter samples were collected in August/September 2009 in the
Arboretum, the adjacent urban forest Königsheide, and a private
garden in Berlin. The litter was collected during a long drought period.
Immediately after collecting the material, the leaves were
sorted; earthy remains and soil animals were removed and leaves
were dried for 48 h at 56 C. The samples were powdered in a
household coffee grinder and 50 g litter were leached with 0.75 L
de-ionized water for 48 h. During the leaching process, the suspen-