Abstract
Several species of epiphytic bryophytes in Sweden are endangered because of habitat loss, which in turn is caused by intensified forestry and changes in the cultural landscape. Several species of common deciduous trees have also been threatened by diseases, which has reduced their numbers. A couple of our environmental goals in Sweden address forestry and the conservation of biodiversity. Since it is known that the red listed species are more common on trees with a higher bark pH I have chosen to compare four common mosses; two that are common in special environments such as tree-lined avenues and parks and two that are common on most trees in western Sweden. This study investigated the difference of bark pH for Leucodon sciuroides, Homalothecium sericeum, Hypnum cupressiforme and Ulota crispa on different host tree species in three different study areas. The hypothesis was that preferences for bark pH differ significantly between the different mosses. It was found that Leucodon sciuroides and Homalothecium sericeum were more common on trees with a higher bark pH while Hypnum cupressiforme and Ulota crispa grew on tree bark with a lower pH. Furthermore it was found that both Hypnum cupressiforme and Ulota crispa could also be found on tree bark with a higher pH. There was also a difference in terms of tree species. The avenue trees had the most species, especially the ash tree.