What factors influence the occurrence of the genus Degelia (a threatened lichen) in central Spain?

The main factors determining the occurrence, abundance, growth and reproductive capacity of threatened lichens need to be known in order to implement conservation initiatives. The main objective of the present study was to evaluate which factors affect the conservation status of Degelia species-complex in central Spain. We undertook a non-parametric analysis to evaluate whether population sizes are larger in protected areas. We fitted generalized linear models (GLM) and mixed models (GLMMs) to analyze which variables are driving occurrence and abundance of Degelia, the thallus size and reproduction capacity. Results show that population sizes of Degelia are very variable, being larger in broad-leaved evergreen forests and inside protected areas. Tree characteristics play an important role in its local dynamics.