Abstracts, XIV OPTIMA Meeting, Palermo (Italy) , 9-15

XIV OPTIMA Meeting, Palermo (Italy), 9-15 September 2013
The effect of microclimate on lichens in the Negev Desert, Israel
TEMINA M.
Institute of Evolution, University of Haifa, Mount Carmel, Haifa, Israel. E-mail: temina@research.haifa.ac.il
Lichens play a pivotal role in the terrestrial food chain, and as providers of nutrients and organic
matter to the ecosystem. They also play an important role in rock weathering and soil formation.
Therefore, any information about lichens in different environments is very important for understanding
the processes occurring in the ecosystems. This is especially important for desert ecosystems where
scarcity of rain may severely limit the ecosystem production. However, the role of many microclimatic
factors in the development of lichen biota in desert areas remains poorly investigated.
The Negev Desert occupies about 60% of the southern part of Israel. The climate of the Negev is
arid with annual rainfall ranging from more than 300 mm in the northwest to about 25 mm in the south.
Most of the Negev area consists of marine rocks, mainly limestones and chalks. Rocks, stones, and soil
of the area are densely covered by microorganisms, including lichens.
To elucidate the role of the desert microclimate in the development and distribution of lichen biota,
lichen communities in different habitats in the Negev desert were analyzed. At each habitat, the rain,
radiation, dewfall, substrate temperatures, and wetness duration were monitored. Special focus was on
studying the influence of the dew moisture regime and substrate temperatures on rates of lichen colonization
of exposed substrates, distribution of lichen growth forms, and on lichen diversity patterns.
The following characteristics of lichen communities were studied: species richness, systematic diversity,
biogeographical elements, frequencies and distribution of species, their morphological and
anatomical characteristics, reproductive strategy, and ecological peculiarities.
Studies showed that the main factor controlling the development of lichen biota in the Negev desert
was dew availability. Dew was responsible for the morphological and anatomical changes in different
lichen species, the fast rate of lichen colonization of exposed substrates, and the structure and distribution
of lichen communities. The comparison of lichen community structures on cobbles in the central
Negev with dew moisture regimes that characterize these habitats indicated species that can be
used as indicators for dew amount and especially for dew duration. The findings may assist us in identifying
lichens that may serve as biomarkers for dew availability and in anticipating changes in lichen
communities following global warming. By serving as biomarkers, lichens may provide important
information on dew regimes in complex terrains where microclimatological data are usually scarce.
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