Habitat conditions and host tree properties affect the occurrence, abundance and fertility of the endangered lichenLobaria pulmonariain wooded meadows of Estonia

Abstract

AbstractWe assessed multiple environmental factors that might influence the population vitality of the epiphytic lichenLobaria pulmonariaat the individual tree and habitat levels in partially overgrown wooded meadows in Estonia. A total of 301 trees of four species were sampled at nine study plots, using a stratified factorial scheme, 151 colonized byL. pulmonariaand 150 not colonized byL. pulmonariaforming the control group. We used the Generalized Linear Models (GLZ) to identify a complex of factors which predicts the probability of the lichen occurring on tree trunks and the presence of apothecia on its individuals. We employed the General Linear Mixed Model (GLMM) to study the relationship between cover ofL. pulmonariaand environmental factors. The occurrence probability ofL. pulmonariaon tree trunks increased with increasing light availability and height of deciduous shrubs near the trunk, and decreased with increasing distance to the nearest colonized tree. The host tree species and its trunk properties were also of importance, particularly the facilitating effect of the cover of bryophytes uponL. pulmonaria. The probability of occurrence of apothecia increased with maximum values of bark pH and cover ofL. pulmonariaon the trunk. We conclude that partially overgrown wooded meadows are suitable habitats forL. pulmonaria. However, to maintain the vitality of these populations, a specific management scheme, preventing development of a dense stand, should be applied. Management requirements would include 1) selective cutting of overgrowing coniferous trees (particularly spruce), 2) preservation of adult and younger potential host trees within 10–20 m of colonized trees, 3) preservation of scattered deciduous shrubs in the vicinity of the host trees.