Contrasting patterns of lichen abundance and diversity in Eucalyptus globulus and Pinus pinaster plantations with tree age

Abstract

We explore the patterns of epiphytic lichen community richness and composition (both taxonomical and functional) on the trunks of the two most important species used for forestry in NW Spain (the non-native "Eucalyptus globulus", and "Pinus pinaster", a native species in the Iberian Peninsula) across a chronosequence of age classes. We recorded a total of 56 lichen taxa in 30 genera across all sites. Lichen abundance and species richness was significantly affected by tree species (eucalypt vs. pine plantations) by age and by the interaction between them. Pines had more lichen abundance and diversity than eucalypts in all ages, with 2–17 times more lichen cover and 2.5–6.5 times higher average species richness, depending on the age. The taxonomical and functional composition of the epiphytic community was also affected by the tree species, the age and its interaction. The colonization pattern in both eucalypts and pines was typical of an additive system, with an ongoing increase of species and epiphytic cover, where early colonizers persist and new species are added later on without replacing the existing species. This study demonstrates that plantations of the native species "P. pinaster" provides a more suitable habitat for lichens than those of the exotic "E. globulus" in the study region, not only as a consequence of longer rotation cycles but for the higher rate of lichen colonization and expansion in their trunks, as these differences were observed in all ages.