Interspecific and intraspecific variability of water use traits in macrolichen species in a fragmented landscape along a climatic ecotone area

Abstract

Water use traits in lichens are important attributes that determine the duration of hydration and metabolically active periods. In this study, the water holding capacity (WHC) and specific thallus mass (STM) were measured for seven macrolichen species (Parmelia sulcata, Parmelina tiliacea, Evernia prunastri, Ramalina farinacea, Lobaria pulmonaria, Lobarina scrobiculata and Nephroma resupinatum) from a Temperate-Mediterranean fragmented landscape. Twenty Quercus forests with different environmental conditions were selected to gather therein five lichen samples of each species in order to analyse their interspecific and intraspecific variation in WHC and STM. The type of photobiont was mainly responsible for differences in the WHC and the water content per biomass among species. Lichens with cyanobacteria as the main or secondary photobiont showed the highest value for both parameters. However, particular features of species were more important in modulating STM, while growth form had a minor explanatory importance. At the intraspecific level, variation in WHC relied on climatic, microclimatic and forest structure factors, while STM variability was only dependent on the two last predictors. Future research should be focused on other drivers at the microscale to unveil the environmental conditions that shape WHC and STM in lichens.