Fine-scale distribution of the epiphytic lichen Usnea longissima on two even-aged neighbouring Picea abies trees

TLDR: Trees with and without U. longissima showed a different pattern in their mineral composition, suggesting that a tree-specific difference in nutritional status might contribute to explain the patchy distribution of this lichen within seem- ingly homogeneous stands.

Abstract: Two neighbouring even-aged 130-yr old Picea abies trees in a homogeneous stand can differ substantially with respect to their epiphytic vegetation. Sampled branches from the canopy of one tree harboured 781 specimens of the old forest lichen Usnea longissima of which only 50 could be seen from the ground, whereas no U. longissima were found on its nearest neighbour. Usnea longissima was most abun- dant on branch tips in lower parts of the canopy on branch segments having the highest biomass of other alectorioid species. Trees with and without U. longissima showed a different pattern in their mineral composition, suggesting that a tree-specific difference in nutritional status might contribute to explain the patchy distribution of this lichen within seem- ingly homogeneous stands.