The Effect of Dew and Fog on Lithic Lichens Along an Altitudinal Gradient in the Negev Desert

The effect of dew upon lichen communities was studied in three sites along an altitudinal gradient in the Negev Desert. The sites [Nizzana, NIZ (250m a.s.l), Sede Boqer, SB (530m a.s.l.) and Har Harif, HH (990m a.s.l.)] have similar rain precipitation (∼100 mm) but different dew precipitation of 0.11, 0.21 and 0.32 mm, respectively. A clear gradient was found for the chlorophyll content with NIZ (38.6 mg m−2)<SB (52.6 mg m−2)<HH (71.3 mg m−2), and the epilithic growth form with NIZ (1.4%) < SB (4.3%) ≪ HH (53.6%) highlighting the fundamental role played by dew in dictating the structure of lichen communities. The findings may assist us in identifying lichens that may serve as biomarkers for dew availability and in anticipating changes in the lichen communities following global warming.