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.
Bibliographical noteFunding Information:
The research was supported by grant 1358/04 of the Israel Science Foundation (ISF). We would like to thank Uri Blya, Valeri Morozovsky, Itai Vonshak, Alex and Leon for their valuable field measurements, Yair Goldreich for providing essential data, and Carol A. Kidron for the editing. We would also like to thank two anonymous reviewers for their most helpful comments. ∗Address correspondence to Giora J. Kidron, Institute of Earth Sciences. The Hebrew University, Jerusalem 91904, Israel; Email: email@example.com An amount of 33 mm per annum spread across 195 dewy mornings has been measured in Avdat, in the heart of the Negev Desert Highlands (Evenari et al. 1982). The frequency of periods during which dew condenses, and the relatively large amounts precipitated in comparison to the ∼90–100 mm of rain precipitation (with 20–25 rainy days) lead ecologists to the conclusion that dew may serve as the main water source for lithobionts (Friedmann and Galun 1974). This was verified for lichens by a set of measurements conducted under controlled (Lange 1969) and field conditions (Kappen et al. 1979; Lange et al. 1970). Field measurements were also conducted in order to examine possible variables that may affect dew condensation.
- dew point temperature
- endolithic lichens
- epilithic lichens
- substrate temperatures
ASJC Scopus subject areas
- Environmental Chemistry
- Environmental Science (all)
- Earth and Planetary Sciences (miscellaneous)