Relations between tree and habitat characteristics and the epiphytic lichen flora on oak : a case study from Lövön, Bohuslän

Abstract: Oak-rich forests and wooded pastures harbor diverse and distinct epiphytic lichen flora with many rare and threatened species. As these habitats have been subject to a substantial decline and degradation over the past centuries, oak woodlands have progressively come into focus for preservation. However, conservation-oriented measures require a thorough understanding of the characteristics of ecologically important host trees and habitats. Therefore, I investigated lichen diversity and characteristics of 50 trees on an island off the west coast of Sweden. Of the evaluated tree and habitat variables, crown encroachment had the highest explanatory value for lichen richness in a highly interrelated web of ecological influences. Combined with stem damage, crown encroachment showed the potential to capture biodiversity on a community level. These findings suggest that light availability, as an overarching primary factor, and microhabitat diversity are the most important characteristics for lichen diversity. Applied to management, this motivates measures to create more open forests with heterogeneous structures.