Lichens of Israel: diversity, ecology, and distribution

Th e biota of lichen-forming and lichenicolous fungi of diff erent plant-geographical regions of Israel was analyzed. Th ese areas diff er in climatic conditions. A total of 350 species from 16 orders, 52 families, and 117 genera were recorded; among them 5% are endemic to the Levant. Th e highest species richness was found in the Mediterranean area. Species diversity of other areas with more arid climatic conditions were much poorer in comparison with species diversity found in the more humid and cooler Mediterranean region. Saxicolous lichens were the most common species. However, in the Sudanian penetration area, terricolous lichens dominated. Among phytogeographic elements, temperate species were dominant. However, the Sudanian penetration area was characterized by the dominance of Mediterranean and subcontinental species. Most of the lichens studied were xerophytic and photophytic species. Th ey dominated all plant-geographical areas of Israel. In the Mediterranean region, mesophytic lichens were also common.


Introduction
Th e fi rst lichens in the Mediterranean region were mentioned in the work of Müller Argo (1884).His paper included information on lichen species collected in the Negev desert.Later, lichenological investigations of this region were continued in the 1940s by I. Reichert, who published several papers on steppe and desert lichens (Reichert 1937a, b;1940).He donated his unique lichen collection comprising specimens from Leba-non, Syria, Jordan, Egypt, and Israel along with his lichenological library to the Department of Botany, Tel Aviv University.Th e collection and library served as the basis for lichenological studies of Israel, which were continued by M. Galun and her students.Among Reichert's students, the famous lichenologist Margalith Galun can be rightly considered as the founder of a new era in the history of Israeli lichenology.In 1958 she, together with Reichert, published her fi rst paper about the lichen fl ora on olive trees (Reichert & Galun 1958).In the 1960s she started thorough fl oristic studies of all regions of the country.Her well known handbook, "Th e Lichens of Israel" (Galun 1970), was the fi rst summary of lichen fl oristic explorations in Israel, which stimulated further lichenological investigations in the country.Her extensive studies including lichen diversity, lichen biology, lichen ecology, and lichen systematics during a period of 40 years extended the body of knowledge available in many fi elds of lichenology not only in Israel, but world-wide.
From 1969 until 1995, many scientists contributed to the knowledge of Israeli lichens.Among these contributions are the experimental works on photosynthetic and respiratory activity of desert lichens in the central Negev by the German scientist O. Lange and his colleagues (Lange et al. 1977).Lange also was engaged by the lichenometric studies in the Negev desert (Lange 1990).A number of interesting studies on the infl uence of air pollution on various characteristics (ecological, physiological, heavy metal content, etc.) of diff erent lichen species were made by J. Garti and his students and colleagues.In the 1980s and 1990s, many investigations were devoted to the question of biogenous weathering of rocks by lichens.Th ey were carried out by Danin and other scientists.On the basis of these studies, Danin proposed to use the patterns of biogenic weathering as indicators of paleoclimates in Israel (Danin 1985(Danin , 1986)).
Since 1996, intensive lichenological investigations have been carried out by the Institute of Evolution, University of Haifa, in collaboration with colleagues from other institutes in Israel and abroad.Th ese investigations are based on past achievements and continue up to the present time.Th ey touch on the diff erent fi elds of lichenology including lichen biodiversity, taxonomy, ecology, biochemistry, genetics, etc.
Th e present study represents a short review of lichens collected in Israel up to 2008.Th e following characteristics of lichen biota were studied: Systematics, species richness, species composition in diff erent regions of Israel, phytogeographical elements, and ecological peculiarities.

Materials and methods
Th e paper is based on the results of expeditions to various regions of Israel from 2000 to 2007, and data collated from literature sources (Galun 1970, Galun & Mukhtar 1996, Temina et al. 2005).Lichen specimens were identifi ed in the Laboratory of Lichenology at the Institute of Evolution, University of Haifa (Israel), applying standard methods.Th e following references were used to identify the specimens: Galun 1970, Clauzade & Roux 1985, Purvis et al. 1992, Wirth 1995, Boqueras 2000, and Temina et al. 2005.Lichen nomenclature follows Temina et al. (2005).Specimens were deposited in the herbaria of the Institute of Evolution, University of Haifa, Israel.To estimate similarity between lichen vegetations of diff erent regions, the Sørensen index (Mueller-Dombois & Ellenberg 1974) was calculated.To analyze local community organization, complexes of lichen species were subdivided into groups based on phytogeographical and ecological characteristics for each species according to Wirth (1995), Temina et al. (2005), and Nimis & Martellos (2008).Th e contribution of each group to the local lichen community was estimated on the basis of relative frequency (Mueller-Dombois & Ellenberg 1974).

Species diversity
Th e biota of lichen-forming and lichenicolous fungi of Israel includes 350 species from 16 orders, 52 families, and 117 genera (Table 1).Among the various families, the highest species diversity is represented by the Teloschistaceae (55 species), Physciaceae (36 species), Lecanoraceae (28 species), and Verrucariaceae (26 species).Th e dominance of these families in species diversity shows a similarity of Israeli lichenobiota and lichenobiotas of the Mediterranean and Irano-Turanian regions.

Species composition of diff erent regions of Israel
Israel is climatically and geographically very variable as indicated by the presence of 29 geo-climatic regions (Rubin & Pick 1994).Th is extensive climatic variability results from the presence of the mesic/desert border and from the widening of the Saharo-Syrian aridity belt (especially during the Pleistocene and Holocene, Tchernov 1975).Four plant-geographical regions are represented in Israel (Zohary 1973): Th e Mediterranean, the Irano-Turanian, the Saharo-Arabian, and the Sudanian penetration (Fig. 1).Th e climate in these regions varies from mesic in the Mediterranean area to semi-arid in the Irano-Turanian area, to arid in the Saharo-Arabian area and to extremely arid in the Sudanian penetration area.Th e largest number of lichens occurred in the Mediterranean area (Fig. 2), which is not surprising, as this area is ecologically more heterogeneous, represents a spatio-temporally "broader niche" (Van Valen 1965) and has more habitat patches and subdivisions than other regions of Israel.Analysis of the Sørensen Indices of Similarity (Table 2) showed signifi cant similarity between lichen biota of the Saharo-Arabian and the Irano-

Ecology of the lichen species studied
Th e main factors infl uencing the distribution of lichens in arid areas are light and moisture conditions.As Fig. 4 shows, most lichens found in Israel represent xerophytic and photophytic species.Th e same groups of species dominate in all plant-geographical regions.However, in the Mediterranean region, high abundances of mesophytic and hygrophytic species were also observed.It is important to note that in this region the frequency of photophytic species is lower than the frequency of these species in other plant-geographical areas with higher solar radiation.

Figure 3 .Figure 4 .
Figure 3. Th e frequencies of lichens on diff erent substrates: A In all areas of Israel B in certain plant-geographical regions of Israel.Abbreviations: Med -Mediterranean region, S-Arab -Saharo-Arabian region, Ir-Tur -Irano-Turanian region, Sud -Sudanian region.

Table 1 .
Systematic diversity of lichen-forming and lichenicolous fungi of Israel.