Thallus hydrophobicity: a low-cost method for understanding lichen ecophysiological responses to environmental changes

Premise: Methods to evaluate lichen thalli hydrophobicity were described in the past, but only recently this was shown to be an important functional trait related to water regulation dynamics that could be used to predict future climate change effects.

Methods and Results: Our protocol requires only a micropipette, distilled water, a tripod and a phone or camera. Hydrophobicity is inferred from multiple metrics associated with absorption times of standardized droplets (initial and total absorption time). We used a dataset of 93 lichen taxa with different growth forms and from different biomes and demonstrated that this method is well suited for capturing different levels of hydrophobicity, including very hydrophilic species.

Conclusions: Our results show that the measurement of lichen hydrophobicity is a rapid and low-cost method to assess an ecophysiologically based lichen functional trait that can be used with almost no limitations, including in different climates, lichen species, and growth forms.