Tree avenues as reservoir for epiphytic lichens in deforested landscapes

Kubiak, D. & Osyczka, P. 2019. Tree avenues as reservoir for epiphytic lichens in deforested landscapes. – Herzogia 32: 398 – 420.Old tree avenues are a disappearing traditional element in European landscapes. Roadside trees constitute an important habitat for many groups of organisms and support the maintenance of biodiversity in deforested areas, but they are often neglected in conservation strategies. This study describes and analyses the conservation value of planted trees along rural roads in NE Poland for epiphytic lichens. A total of 105 trunks of seven deciduous tree species were examined. Lichen species inventories were assembled for trunks at a height up to two meters from the ground. A total of 99 lichen species was recorded. Lichen species richness and cover were dependent primarily on tree species. Diameter of trees was not significantly correlated with the number of species. Ulmus laevis and, to a lesser extent, Fraxinus excelsior and Acer platanoides, were be the most valuable tree species in terms of lichen species richness. Quercus robur as a roadside tree did not have above-average species numbers. Lichen species with a preference for eutrophicated or alkaline bark occurred in their largest numbers on Populus nigra agg. Betula pendula hosted the largest number of species avoiding eutrophication. Each tree species had its own set of exclusive lichens and hosted taxa which are red-listed in Poland; however, no single tree species alone guarantees preservation of the entire range of epiphytic lichens on roadside trees in the study area. Since tree avenues, especially those composed of multiple species, provide a suitable habitat for various rare and endangered lichens, potentially high conservation value should always be attributed to this element of local landscapes in low pollution areas.