Tree decay modulates the functional response of lichen communities in Patagonian temperate forests

Epiphytic and epixylic lichens respond negatively to forest degradation, climate change and pollution, but those effects may depend on functional traits or interact with the stage of tree decay. Disentangling the main drivers of lichen communities remains a challenge in regions where lichens are diverse and poorly known, as the case of Patagonian temperate forests. We used a multi-scale approach to evaluate the relationship between environmental variables, tree decay stage and lichens. We sampled lichens across three increasing scales (tree ≪ site ≪ landscape) by selecting 19 landscape units, where trees in four decay stages (snags, logs, cavity trees and healthy trees) were selected within sampling plots. A total of 35 predictors were measured over different scales, including 25 remote sensing indices of forest conditions, climate and air pollutants. Structural Equation Models were used to test the causal linkages of predictors with lichens, distinguishing functional categories (size, growth and reproductive strategy). A total of 69 lichen species were recorded. Cavity trees and logs supported the largest diversity, while snags and healthy trees had the lowest diversity. Functional lichen groups responded differently to fine-scale variables, including the diameter, height, density and pH of trees. Air pollutants affected species with sexual and mixed strategies. Lichens were sensitive to precipitation, temperature and wind speed, with foliose and sexual species responding positively to the latter. The abundance of all species and macrolichens increased with tree senescence and decreased with canopy continuity. Lichens occupying snags and logs responded negatively to primary productivity and tree senescence, but positively to soil organic matter. Our findings suggest: i) the functional structure of lichen communities varies non-linearly with the wood decay process; ii) the reproductive strategy influences the sensitivity to air pollutants, iii) climate variables influence dispersal and colonization of woody substrates; and iv) forest structure/succession interacts with tree decay.

Data on epiphytic lichens and their host-trees in relation to non-forested area and natural deciduous lowland forest

The article includes raw and analyzed data directly related to the research paper entitled “Non-forested vs forest environments: the effect of habitat conditions on host tree parameters and the occurrence of associated epiphytic lichens” [1]. These data concern the relationships between the composition of lichen communities and host-tree parameters in non-forested area and a natural lowland deciduous forest in northern Poland. Lichen species confined to non-forested area, associated with forest habitat, and non-specific mutual species occurring in both habitat types are listed together with their host-tree preferences. Data on the phenotypic variability of five common and native to Central Europe tree species in relation to the habitat type are provided. Data that concerns tree parameters are analyzed by the mixed model ANOVA and Principal Component Analysis. Additionally, sample rarefactions and indices of potential lichen species richness for both habitat types are included. Presented data could be used in further studies to compare epiphytic community structure and may be support for campaigns aimed at lichen conservation and at shaping the environment with concern for biodiversity.