Flora and Vegetation of Israel

and adjacent areas

Avinoam Danin

Department of Evolution, Systematics and Ecology

The Hebrew University of Jerusalem

Jerusalem, Israel

The Flora

Israel is a meeting area of plant geographical regions and has high climatic, lithologic, and edaphic diversity. These factors, together with prolonged influence of human activity, have led to the development of rich flora and diverse vegetation. The basic taxonomic research of the country's flora, "Flora Palaestina", was completed in 1986 (Zohary, 1966, 1972; Feinbrun-Dothan, 1978, 1986). Later, a new Analytical Flora in Hebrew was published (Feinbrun-Dothan and Danin 1991). A manuscript of a new distribution Atlas of plants in the Flora Palaestina area was submitted (Danin, 2001a) to the Israel Academy for Science and Humanities, including also revision of many of the plant names.

Eig (1931-32; 1946) have established the foundations of the geobotanical research in Israel. The history of geobotanical and floristic research until the 1970's was reviewed by Zohary (1962; 1973). In the last two decades many Ph.D. and M.Sc. theses were carried out. Many of these theses were written in Hebrew and are not available to those who do not read this language. The vegetation of parts of the Galilee was studied by Rabinovitch (1970, 1979), and Berliner (1971); of Mt. Hermon by Shmida (1977); of the Judean foothills by Sapir (1977); of the southern Negev by Lipkin (1971). Much of the present information was summarized in Waisel (1984, in Hebrew). The vegetation of the Negev Highlands and the Coastal Plain was reviewed and officially described recently (Danin & Orshan 1999). In the following account a general description of the flora, i.e., the list of species with their geographical affinities, and vegetation of Israel is presented. In order to open the description of vegetation to a wider audience the use of the modern phytosociologic nomenclature is avoided the general non-ranked term "plant community" is used to to describe the principal vegetation units of the country.

Within Israel's present boundaries of the vegetation map, including Mt. Hermon, the number of plant species is 2825 in an area of 29,600 km2. Without Mt. Hermon the number of species is 2600. This number is high compared with many other countries. For example, the Californian coastal zone, with an area more than twice as large as Israel has 2325 species (Johnson & Raven 1970). The number of species divided by the area or the log species/log area of Israel has the highest value when compared to Mediterranean and European countries (Table 1). Israel's high species richness expressed as species/area or log species/log area results from two factors: 1. Its position in a meeting zone between plant geographical regions, each with a typical flora; and 2. The existence of many habitats that are needed to support these species. The wealth of habitats derives from the climatic transition between the relatively moist area in the northern part of the country and the desert in the southern part. Topography is a second factor in creating the warm climates of the Jordan, Dead Sea, and Arava valleys, and the relatively cold climate of Mt. Hermon. In a similar way other highlands and lowlands have local climatic influence which increases Israel's habitat diversity. The geomorphological structures are relatively small but the number of rock types is high. As a result, many soil types develop in a small area (Dan & Raz 1970) increasing the diversity of habitats. A long history of human activity of cultivation, and grazing by domestic animals led to strong stress on the existing flora and enabled the introduction of many alien species. Many of the latter established themselves in synanthropic habitats (Zohary 1973; Danin et al. 1983; Danin 1991a, 1991). According to Eig (1931-32), Zohary (1962; 1966; 1972), Feinbrun-Dothan (1978; 1986), and Danin & Plitmann (1986), the flora of Israel is divided into seven groups with general distribution area as follows:

1. Mediterranean (M) species, which are distributed around the Mediterranean sea.

2. Irano-Turanian (IT) species, which also inhabit Asian steppes of the Syrian desert, Iran, Anatolia in Turkey, and the Gobi desert.

3. Saharo-Arabian (SA) species, which also grow in the Sahara, Sinai, and the Arabian deserts.

4. Sudano-Zambesian (S) species, typical to the subtropical savannas of Africa.

5. Euro-Siberian species, also known in countries with a wetter and cooler climate than that of Israel; growing mainly in wet habitats and along the Mediterranean coasts.

6. Bi-regional, tri-regional, and multi-regional species that grow in more than one of the regions mentioned above.

7. Alien species from remote countries; these plants propagate without human assistance. The principal countries of origin are the Americas, Australia, and South Africa. The percentage of aliens in the Flora Palaestina area is 5.7% of the entire flora (Danin 2001).

Eig (1939) followed by Zohary (1962) delineated four plant geographical Territories in Israel:

1. Mediterranean, 2. Irano-Turanian, 3. Saharo-Sindian; and 4. Sudano-Decanian enclaves. Zohary (1966) renamed some of the phytogeographical regions and regarded Eig's Saharo-Sindian as Saharo- Arabian and Eig's Sudano-Decanian as Sudanian. Eig's Sudano-Decanian enclaves in the Dead Sea area became a "territory of Sudanian penetration" (Zohary 1966).

In a recent analysis of the plant geographical territories of Israel and Sinai (Danin & Plitmann 1987), the criteria for subdividing the country was based on more than 80,000 observations of plant- location in a 5 x 5 km square grid. Similarity of prevalence of the first two chorotypes was used to lump individual squares into provisional plant geographical territories. Floristic lists were prepared for these territories and the frequency of each chorotype was recalculated. Statistical analysis (the log-likelihood ratio for contingency = G-test, Zar 1984) was operated for each pair of territories. In addition, the floristic lists for the districts of Sinai (Danin 1983; Danin, Shmida & Liston, 1985) were analyzed by the same method. The threshold of chi-square probabilities for lumping two districts in Sinai into a plant geographical territory was p< 5%. The same test and threshold were used to analyze the plant geographical territories of Israel and Sinai.

The result of the latter analysis is a map with pie diagrams for each of the territories. The Mediterranean territory is rather similar in extent to that of Eig (1931-32). All other territories are "complex territories" where the second most frequent chorotype is in parentheses. These included the following: M(M-IT), SA(M), SA(IT), SA(S), IT(SA), and S(SA) (cf. Fig. 1).

A phytogeographical analysis of the geographical districts of Israel and Jordan is presented in Table 1. The results imply that several geographical districts display a highly similar spectrum of chorotypes. Such are districts 1 through 11 and 13, 15, 30, and 31. These similarities led us to revise the floristic subdivisions of the study area.

Floristic subdivisions of Israel in the geographical data base of the Botanical Garden, Jerusalem

Eretz Israel (Palestine) was divided into geographical subdivisions already in the first Analytical Flora (Eig, Zohary & Feinbrun 1931). Some 20 geographical domains were listed in the text, without any map displaying accurate boundaries. The districts listed (in a north to south and west to east sequence) are: Acco Plain, Sharon, Shefela, Upper Galilee, Lower Galilee, Esderaelon Plain, Gilboa, Carmel, Samaria (Shomron), Judean Mts., Negev, Judean Desert, Hula, Upper Jordan Valley, Bet-Shean Valley, Lower Jordan Valley, env. of the Dead Sea, Gilead, Moav, Edom. Many plants are recorded as occurring in Transjordan. In the second edition of the Analytical Flora (Eig, Zohary & Feinbrun 1948) there is a map (p. 501) of Eretz Israel with 23 districts. The Negev is not clearly divided in that map, the Philistean Plain (Pleshet at present) is called “Shefela” (at present this name is used by most geographers for the Judean foothills); the Judean Desert includes the Samarian Desert, and the Lower Jordan Valley includes the Dead Sea Valley. Twenty-nine districts are presented in the map of “Flora Palaestina” (Zohary 1966, 1972; Feinbrun 1978, 1986). These include a few independent districts, e.g. the Coast of Carmel (separated from the Sharon of 1948’s map) and Acco Plain of 1948 which was divided to the Coast of Galilee and to Acco Plain proper and parts of the western Galilee which were transferred back into the Galilee. The Gilboa was separated in Flora Palaestina (Zohary 1966) from Samaria, parts of the Samarian Desert became included in 1966 map in Samaria; The Dead Sea area became separated from the Lower Jordan Valley. Feinbrun-Dothan & Danin (1991) followed the subdivision of the Flora Palaestina area, but changed a few boundary lines in the Negev, and marked the Samarian Desert as an independent unit following the increasing botanical knowledge of these areas (Danin 1970) and unpublished investigations. In the New Analytical Flora Zohary (1976, 1989) changed the districts without a clear demonstration of boundaries in a map. Botanical-geographical information collected during 30 years became incorporated into a data base managed with Microsoft Access Software (Danin, unpublished) where the species are registered in squares of 5 x 5 km for Israel and 10 x 10 km for Jordan. This database became the source of information for a few comprehensive investigations on the country’s flora. A phytogeographical map of Israel and Sinai (Danin & Plitmann 1987) displays the principal phytogeographical territories typified by the most frequent chorotype in the list of species (see above, the last paragraph of the “The Flora chapter) . The chorotypes listed in Flora Palaestina (Zohary 1966, 1972; Feinbrun 1978, 1986) were used as the basis for Danin & Plitmann (1987) analysis. Hence, the latter subdivision was not completely objective, as there was a high weight to the phytogeographical perception of M. Zohary and N. Feinbrun-Dothan. A substantial contribution to the latter was the Ph.D. thesis of Gruenberg-Fertig (1966). Critical notes on this perception as presented in “Flora Palaestina” are found in White & Leonard (1991).

Analyses of the flora of Israel in which the basic unit analyzed was the actual species and their distribution in squares of 5 x 5 km (hence, totally objective) were carried out by Kadmon & Danin (1997, 1999). Resulting from analyses in advanced statistical methods, one can see in the three maps in these studies high resemblance to the phytogeographical map of Danin & Plitmann (1987). Consequently the present author concludes that in dividing the study area into botanical districts, using the plant distribution information as criteria for the subdivision, it is not justified to make 20 districts (as in Eig, Zohary & Feinbrun 1931) or 31 district (as in Feinbrun-Dothan & Danin, 1991, or Danin 2001) but into 5 (Fig. 2 ). Mt. Hermon supports at its upper elevation belts flora which is not included in the analytical floras of Eig, Zohary & Feinbrun (1931, 1948), neither in the first edition of Flora Palaestina (Zohary 1966, 1972; Feinbrun 1978, 1986), and nor in its second edition (Danin, 2001). Mt. Hermon’s flora is included in the New Analytical Flora of Zohary (1976, 1989) and in Feinbrun-Dothan & Danin (1991). Mt. Hermon constitutes a special floristic domain in Israel. Its lower part from 200 through 1300 m above sea level is covered by a flora, which belongs to district 1 in the present account. The flora of the area above 1300 m is Oro-Mediterranean and only a few species of this flora occur in the rest of Israel. Therefore, many of the species of Israel are listed here as belong to districts 1 & 5 or of 5.

The lists of species in Israel and its neighbouring countries counts:

Israel without Hermon 2598 species

Israel with Hermon 2825 species

Israel and Jordan without Hermon 2748 species

District 1 2210 species

District 2 1435 species

District 3 1070 species

District 4 1056 species

District 5 998 species

Table 1. Distribution groups in the 5 biotope-districts of Israel

Districts	1	2	3	4	5
No. species	946	18	37	99	216
Districts	1 + 2	1 + 3	1 + 4	1 + 5	2 + 3
No. species	185	41	37	296	16
Districts	2 + 4	2 + 5	3 + 4	3 + 5	4 + 5
No. species	37	3	33	5	1
Districts	1+2+3	1+2+4	1+2+5	1+3+4	1+3+5
No. species	115	72	152	16	8
Districts	1+4+5	2+3+4	2+3+5	1+2+3+4	1+3+4+5
No. species	6	138	2	389	3
Districts	1+2+3+5	1+2+4+5	2+3+4+5	1+2+3+4+5
No. species	81	40	2	185

3. Vegetation

The plant communities which occur in a particular place are

influenced by their phytogeographical positions, climatic factors,

lithology, soil, and human activities. The principal plant communities

that make up the vegetation map units (Fig. 3) are listed below in the

legend's sequence with a description of the environmental factors

affecting their distribution and phisiognomy.

1) Maquis and forests

The principal woodlands are found in the mountains of Judea, Carmel, and Galilee. In most of the area cultivated plants have replaced the spontaneous trees. A few thousand years ago, people in Israel, as in the neighboring Mediterranean countries, started to clear the natural vegetation in order to create agricultural land. Trees that have been domesticated from the spontaneous flora of Israel (Zohary & Spigel-Roy 1975), such as olives (Olea europaea) and almonds (Amygdalus communis) today cover large parts of the previously existing woodlands. The timber derived from the forests and maquis was used for the construction of houses, for agricultural tools, and for fuel. Areas of supressed maquis support herbaceous vegetation which has higher nutritional value than the evergreen trees and shrubs. For the last few millennia shepherds burned large woodland areas to open paths for the domestic animals, and improve pasture quality while supressing the arboreal vegetation.

After cultivated ground is abandoned, the area becomes populated by low herbaceous and low lignified plants for dozens of years. This vegetation formation of Mediterranean semi-shrubs covering the entire area is locally known as "batha" (= phrygana). In the last century, a large proportion of these batha areas have been reforested by the state of Israel. Pinus halepensis, which grows spontaneously all over this mapping unit is the principal tree in the planted forests.

Thus, the area of this unit is a mosaic of areas that have been influenced to a varying extent by human activity. In areas slightly influenced, it is possible to study the relationship between vegetation and edaphic factors. Trees which survived in the margin of cultivated land or sanctified trees assist us in identifying the woodland boundaries.

A. Quercus calliprinos woodlands on limestone.

The principal rock types in this category are hard limestone and dolomite. Terra Rossa soil is found on those rocks. This soil is well aerated and is poor in nutrients due to the efficient leaching. Tree roots penetrate into joints and crevices in the rock to a depth of 8-10 m and use resources from the entire depth. Evergreen sclerophyllous maquis, dominated by Q. calliprinos develop on this substratum. A stand of such a maquis may be totally covered by trees that are accompanied by a few vines and plants adapted to shade. Oak trees with many trunks are rather common throughout. This is a result of human activity; after a tree is cut, overgrazed, or burnt, many new stems sprout from the rootstock, thus giving rise to trees with several trunks.

A woodland with 10-12 m tall trees of Q. calliprinos, Q. boissieri, and Arbutus andrachne occurs at the upper Galilee, constituting a part of the Mt. Meiron nature reserve. In most other maquis areas, the tree canopy is less than 4-5 m high. Thus, the status of the woodland may indicate local appropriate environmental conditions A few sanctified trees have overcame the hazards of human activity. The graves of holy men in their shade furthers the Moslems belief that a curse will fall on the one (or his herds) who cuts the tree stems. This idea has protected the trees for centuries. Thus, such ancient trees are found all over the unit area; in Hebron, Jerusalem, and En Hemed (Aquabella), in the Judean mountains, the "Wood of the Forty" on Mt. Carmel, and near many graves in the Hermon, Golan, Galilee, and Samaria.

The companions of Q. calliprinos vary according to edaphic and climatic conditions. In the Upper Galilee, where the climate is the moistest in Israel, the mesophytic companions are the following: Rhamnus alaternus, R. punctatus, Eriolobus trilobatus, Acer obtusifolium, Crataegus azarolus, C. monogyna, Laurus nobilis, Hedera helix, Ruscus aculeatus, Paeonia mascula, and many herbaceous species. None of these mesophytic components occur in the maquis of the Judean mountains. In the driest maquis stands, Rhamnus lycioides subsp. graecus is the only arboreal companion of Q. calliprinos.

In the Galilee, special edaphic conditions are reflected in the maquis composition. In the western Galilee, near Maalot, Laurus nobilis dominates the maquis. Rabinovitch (1979) found that the Terra Rossa there is poor in magnesium. L. nobilis is the tree best adapted to this stress.

Kaolinitic Terra Rossa develops on Eocene limestone in the eastern Galilee, Mt. Gilboa, and near Shechem (Nablus). This soil has a low moisture holding capacity, low cation exchange capacity, and a relatively high phosphorous content. These conditions, especially the high phosphorous content, intensify the development of herbaceous annuals and perennials. These herbaceous plants compete with tree

seedlings for water and intensify fire hazards in summer. When compared with other Terra Rossa areas, the kaolinitic areas are green in moist winters but look like deserts in summer.

The most common semi-shrub that grows on abandoned Terra Rossa soils (excluding the kaolinitic Terra Rossa) is Sarcopoterium spinosum. This plant dominates bathas in the boundary of the Mediterranean territory with the steppe vegetation. It is believed that its primary habitat is in the latter area because, in moister parts of the country, when the maquis components develop and overshade the s. spinosum shrubs it dies. The typical semi-shrub companions of S. spinosum in the moist Mediterranean bathas are the following: Fumana arabica, Cistus creticus, C. salviifolius, Salvia fruticosa, Teucrium divaricatum, T. capitatum, and Phlomis viscosa.

b. Quercus boissieri woodlands

Maquis dominated by Q. boissieri develops in the Upper Galilee, on north-facing slopes where solar radiation is relatively low, and on the relatively moist Terra Rossa soils. The winter deciduous Q. boissieri is accompanied by deciduous trees such as Cercis siliquastrum, Pyrus syriacus, Prunus ursina, and Crataegus azarolus.

c. Pinus halepensis and Arbutus andrachne woodlands

Marly-chalk is another common rock type. It has a high moisture holding capacity and when weathered, it is covered with Light Rendzina soil. The aeration of the rhizosphere of trees that penetrates into the soft rock is poor and only specially adapted plants develop there. Much of the nitrogen in this soil is in the form of ammonium ions whereas in the Terra Rossa it is in the nitrate form (Rabinovitch 1979). The vegetation cover of the Light Rendzinas on marly-chalk is

poor when compared with Terra Rossa. There are only few annual companions in the batha or maquis stands on this soil. In sites with high clay content of the rock and low aeration, Arbutus andrachne is the dominant. Symbiosis of tree roots and fungi (mycorrhiza) seems to enable the success of A. andrachne there. The only arboreal companions of A. andrachne here is Pinus halepnsis; its mycorrhizal fungi (Suillus granulatus) is the most common edible winter mushrum species in Israel.

P. halepensis grows on marly-chalk without A. andrachne in sites with low clay content. Near Bet Jan, the Upper Galilee, there is the only known slope with marly-chalk where Juniperus oxycedrus accompanies P. halepensis and A. andrachne.

Among the trees or in clearings of this marly-chalk ground there are stands dominated by one or a few semi-shrubs of: Fumana thymifolia, Coridothymus capitatus, Cistus creticus, C. salviifolius, Helianthemum syriacum, Satureja thymbra, Thymbra spicata, and Teucrium creticum. These are accompanied by many Orchidaceae species, the diversity of which increases from the Judean mountains to the Galilee.

2) Quercus calliprinos woodlands on basalt

Maquis dominated by Q. calliprinos develops on basalt and other volcanic substrata in the Golan at an elevation of more than 500 m above sea level (a.s.l). There are very few lignified semi-shrub, shrub, or tree companions to the dominant oaks. When compared with 100 year old maps, the woodlands range substantially decreased. In many parts of this unit, the maquis is developed on shallow rocky soil and looks like straight lines of hedges between agricultural fields. Since at least 1967 there is no ploughing there and rich ephemeral herbaceous vegetation develops among the trees. No establishment of new tree seedlings takes place in the grassland among the "hedges". The successfully growing herbaceous plants outcompete the tree seedlings which can’t find sufficent water to survive the first summer of their life.

Near mas'ada, at elevation of 900-1000 m, the gentle north facing slope of the ancient volcanic cone of Har Odem is covered by a dense maquis of Q. calliprinos. It is accompanied by Q. boissieri, Crataegus monogyna, C. aronia, and Prunus ursina. Among the trees, the rich ephemeral vegetation includes some 20 species of Trifolium. There are a few Orchidaceae at the trees shade. Most tree trunks and thick stems are covered by mosses and lichens that probably enjoy the frequent events of wetting by low clouds. In other parts of the oak woodland there are Pistacia palaestina trees in the hedges and at the center of opened rectangular herbaceous areas, at elevation of 800-900 m, there are trees of Quercus ithaburensis and Pistacia atlantica. The latter are known as components of more drought resistant vegetation. The proportion of oak trees decreases towards the boundaries of the thick woodland; solitary occasional trees, mostly of Crataegus aronia and Prunus ursina indicate the once existing oak woodlands in much larger areas.

Many species which develop in similar stands of maquis at the Upper Galilee on Terra Rossa do not grow here. Such are: Arbutus andrachne, Laurus nobilis, Pinus halepensis, and Rhamnus alaternus. In most of the area there is a prominent influence of the inhabitants of the villages Majdal Shams and Shab'a. For centuries they cut the lignified stems and their goats graze on the young sprouts. Since 1967 part of the area is protected and many plants that are not known from other parts of Israel are found here. The typical arboreal plants are: Quercus boissieri , Q. libani, Juniperus drupacea, Acer monspessulanum subsp. microphyllum, Cotoneaster nummularia, Crataegus monogyna, Prunus ursina, and Amygdalus korschinskii. These trees are accompanied by a few perennial grasses and many annuals; of these some are typical for montane belts, others are Mediterranean maquis plants, and others are typical to the semi-steppe bathas. Most of the semi-shrubs here are known also from the "tragacanth vegetation" (cf. unit 9).

4) Park forest of Quercus ithaburensis

Park forest is a vegetation formation of trees, the canopies of which do not totally cover the area. In many places in Israel and its neighboring countries, it is evident that such a formation is found in drier and warmer areas than those of Q. calliprinos woodlands. This latter develop in the Golan (unit 2) at elevation of 500-1,200 m whereas at the elevation belt of 0-500 m there is a park forest of Q. ithaburensis or its remnants. Within the areas covered by Q. ithaburensis relatively moist habitats, such as steep north-facing slopes and highly rocky areas, are covered by Q. calliprinos or its companions.

Q. ithaburensis is a Mediterranean tree from a section in the genus which was originated in the Irano-Turanian region. Its relatives constitute park forests over large areas of the Zagros mountains in Iran (Zohary 1973). Q. ithaburensis dominates in three principal soil types and it is not clear yet what they have in common. Hamra (sandy-loam) is a soil derived from Pleistocene sand dunes in the Sharon between the Yarkon river and Mt. Carmel. There are many evidences that the Q. ithaburensis woodlands prevailed in the coastal area of Israel until the last century. A few remnants of Q. ithaburensis forest on Hamra occur in the Sharon. The largest reserve is some 20 large sanctified trees in Horvat Cherkes near Pardes Hanna. It was a cemetery of a Cherkes village that existed in the vicinity. The Hamra soil has a clay layer at a depth of 2-3 m where much of the oak roots

are harbored. It is a rather unique type of soil and supports several endemic and many rare species. Most of the area in the Sharon that is covered by Q. ithaburensis forest supports in the last century orange orchards. In areas that have been cultivated and abandoned Centaurea procurens and Desmostachya bipinnata community develops.

At the Alonim-Shefaram and the Menashe Hills, there is a park forest of Q. ithaburensis on Eocene hard chalk with Dark Rendzina (Aloni & Orshan, 1972). The tree roots penetrate these rocks and use much of their resources from there. Therefore, rock quality seems to have an important influence on the success of that oak there. The principal semi-shrub companion is Majorana syriaca; there is a rich

herbaceous vegetation of Graminae and Papillionaceae. In spring there

develop among the trees carpets of Cyclamen persicum and Anemone coronaria, both in divers colours. The arboreal companions are the following: Styrax officinalis, Pistacia atlantica, P. palaestina, Rhamnus lycioides subsp. graecus, and Quercus calliprinos. It is here where Nari crusts (hard rock developing during pedogenetic processes on top of soft rocks) and north facing slopes support mainly Quercus calliprinos and its companions.

The Yahudia forest reserve, at the Golan, is principally a park forest of Q. ithaburensis on basalt. Here trees grow mainly on large rock mounds accumulated by man some 4,000 years ago (Epstein, 1974). There are very few arboreal companions to the oak, such as Pistacia atlantica, Ziziphus spina-christi, and Z. lotus. The latter two develop mainly on the stony ground among the rock mounds. The open areas among trees support rich annual herbaceous vegetation dominated

by grasses with large seeds. Such are Triticum dicoccoides (wild wheat), Hordeum spontaneum (wild barley), and Avena sterilis (wild oat). These are strong competitors to the tree seedlings and only in the rock mounds where annuals do not grow can the seedlings survive the first summer and the frequent fire hazards. Rodents (mainly wood-mice, Apodernus) that live in the mounds commonly eat the non-bitter half of the oak acorn and leave, in the mound, the remaining

bitter half that contains the embryonic root and shoot. Another reason

for oak establishment in the mounds may be the protection of its acorns

from wild pigs.

Pistacia atlantica, which accompanies Q. ithaburensis, is the principal tree of the park forest on hard limestone of the eastern Galilee between Har Kena'an and Metula. Tree density here is less than that of the Q. ithaburensis woodlands. The arboreal companions of P. atlantica are Amygdalus korschinskii, Rhamnus lycioides subsp. graecus, Styrax officinalis, Pistacia palaestina, and Crataegus aronia. Many seedlings of trees establish themselves in rock crevices. Here

seedlings are protected from competition and fire hazards that are associated with the rich annual vegetation as discussed above for Q. ithaburensis at the Golan. The principal annual companions here are the same species of Triticum, Hordeum, and Avena with plenty of other Graminae, Papillionaceae and Compositae species.

5) Park forest of Ceratonia siliqua and Pistacia lentiscus

Ceratonia-Pistacia lentiscus park forest develops on all the limestone hills at the foot of the central mountain range of the Mediterranean zone of Israel in Judea, Samaria, Carmel, Gilboa, and Galilee. This plant community is more drought and heat resistant than that of Quercus calliprinos, and develops at elevation of 0-300 m

a.s.l. On calcareous sandstone (Kurkar) this community develops close to the Mediterranean coast from Netanya to Mt. Carmel. Here it is accompanied by typical sand plants that develop on coastal dunes (Kutiel et al. 1978/9; Danin & Yaalon 1982). Sand covering the park forest led in places to complete destruction of the forest. The vegetation developing on the sand leads to amelioration of its water regime by producing humus and becoming a trap for airborne fine

grains. At the first stages of plant succession desert plants such

as Artemisia monosperma, Helianthemum stipulatum, and Retama raetam

grow on the sand. During amelioration of the moisture regime, following the trapping of airborne dust, the desert shrubs die and are replaced by typical Mediterranean shrubs such as Calicotome villosa, Rhamnus lycioides subsp. graecus, R. alaternus, and Pistacia lentiscus. Ceratonia siliqua germinates and

establishes itself in the shade of Pistacia lentiscus. It is evident that on the sand cover only in the micro-habitats created by plants the carob seedlings can survive. Further research is needed to discover the role of the overlain rock in the carob re-establishment.

The composition of the Ceratonia siliqua - Pistacia lentiscus community varies with edaphic and climatic influences. At the southern Judean foothills Rhamnus lycioides subsp. graecus is the principal companion. At Mt. Carmel and the western Galilee Olea europaea (wild olives) and Quercus calliprinos accompany Pistacia lentiscus which is the principal shrub companion there. On the south facing cliffs of Mt. Carmel the companions are rock plants such as Micromeria fruticosa, M.

myrtifolia, M. nervosa, Chiliadenus (Varthemia) iphionoides, and Stachys palaestinus. Perennial grasses of Sudanian origin, such as Hyparrhenia hirta, Pennisetum orientale, and Tricholaena teneriffae grow in the rock crevices as well. Here they get sufficient warmth and their rhizosphere is protected by the rocks from competition with the Mediterranean herbaceous plants.

Ceratonia-Pistacia lentiscus community is developed on large areas east of the water divide of Samaria, Gilboa, and Galilee mountains. The occurrence of a few carob trees along the western boundary of the Judean desert and north of the Negev may indicate the existence there of a similar Ceratonia-Pistacia lentiscus park forest in the past.

6) Ziziphus lotus with herbaceous vegetation

The southeastern hilly area of the Galilee looks like a park forest, but without trees. Instead, there are scattered shrubs of Ziziphus lotus over large areas of the typical herbaceous Mediterranean grasses. The herbaceous plants are species of Hordeum, Triticum, Aegilops, Avena, Trifolium, Medicago, and other Graminae,

Papillionaceae, and Compositae. The substratum in the northern area of this unit is basalt and in this respect it is similar to the southern Golan; however, this is a drier area and no Q. ithaburensis trees develop here except for near Mt. Tabor at the western part of this unit. Z. lotus is one of the most drought resistant shrubs in Israel that grows in the northeastern parts of the country. It sheds leaves in winter and renew its growth in spring. Its spiny shrubs function as a hiding and resting place for many animals; these enrich the soil with their droppings. Under and near the Z. lotus shrubs there is a lush herbaceous vegetation where plants are much larger than in the opened area between the shrubs. Ruderal plants such as

Chrysanthemum coronarium and Silybum marianum often grow in this microhabitat.

7) Savannoid Mediterranean vegetation

Spiny trees of Sudanian origin, mainly Ziziphus spina-christi and in a few places Faidherbia (Acacia) albida grow in areas that seem to be too warm and dry to support Mediterranean trees. These trees are accompanied by Mediterranean herbaceous vegetation. Since in the true east African savannas the spiny trees are accompanied by Sudanian herbaceous vegetation that do not grow here we use the term "savannoid" to imply that it is a savanna-like vegetation. In the Golan, from sea level to 200 m below sea level, Z. spina-christi grows all over the slopes and is accompanied by herbaceous vegetation that is similar to that of unit 6. South of lake Kinnereth the companion grass is Stipa capensis that also grows in desert areas. In this area and to the south Z. spina-christi grows in wadis and near springs. At the foot of Kokhav HaYarden, near Gesher there is a dense savannoid vegetation dominated by Faidherbia albida. It reproduces there vegetatively from roots and only a few large specimens produce pods with one or two seeds in each. Apart from here, F. albida occurs in Israel in a few isolated thickets near Nahallal, the Esderaelon plain, in Emek HaElla at the Judean foothills, near Kefar Menahem, near Ramla, and at the Mediterranean coastal plain near Ashdod and Ashqelon. The principal area of the species is savannas in east and south Africa. In its African primary habitats it reproduces from seeds. It is regarded in Israel as a disjuncted relict of the Tertiary (Halevy 1971). Z. spina-christi is an East African tree that sheds leaves there in the drought season. In Israel it grows in habitats with sufficient water; however, in some areas it may suffer some years from low temperatures in winter and may shed leaves as a response to this stress. In considerable parts of the coastal plain south of the Yarkon river there are stands of this unit. The principal tree there is Z. spina-christi, which is accompanied by various Mediterranean companions the composition of which is related to the particular soil type (unit 19b). All throughout the area of this unit there are occasional trees of Parkinsonia aculeata in the savannoid vegetation. It is an adventive thermophilous tree, of Central American origin, which was introduced to the country as an ornamental tree and establishes itself on disturbed ground.

8) Semi-steppe batha

The vegetation boundary of the Mediterranean territory towards the desert, where mean annual rainfall is 250-350 mm, is bathas of semishrubs. Trees are rather rare and are confined to habitats where additional water concentrates. Such are wadis and crevices of large outcrops of smooth rocks. In addition to the Mediterranean plants there are various plants that grow in neighboring desert areas as well. Many species that grow in this unit in primary habitats grow in synanthropic habitats at the center of the Mediterranean territory. Sarcopoterium spinosum dominates over large areas in this unit and there are no competitors that may cause shade over the plant and lead to its death. At the center of the Mediterranean territory bathas of S. spinosum are replaced in time by shrub and tree formations. Only a few species grow over the entire area of the unit; such are Phlomis brachyodon and Ballota undulata. The entire vegetation class is named Ballotetea undulatae (Danin & Solomeshch, 1999). Hard limestone in the southern Judean mountains are occupied by communities of S. spinosum, Phlomis brachyodon, and Thymelaea hirsuta. Astragalus bethlehemiticus and Euphorbia hierosolymitana accompany S. spinosum on the high terrain near Har Amasa.

Chalky ground is covered by communities dominated by Echinops polyceras, Alkanna strigosa, Ononis natrix, and Artemisia sieberi. Some of the typical desert plants that grow in these communities because of the poor moisture regime are the following: Artemisia sieberi, Noaea mucronata, Bellevalia desertorum, Scorzonera judaica, and Fagonia mollis.

The vegetation of the deep clayey soils in small valleys and plateaux in this unit include many herbaceous plants which were regarded by several authors as exclusive weeds of similar soils that are cultivated in the Mediterranean territory. Such areas near the 1948-1967 border in southern Judean mountains, were not cultivated for 19 years and harbored Phlomis pungens, Salvia syriaca, Astomaea seselifolium, Ferula biverticellata, and Scolymus maculata. This may indicate that the latter species are not obligatory weeds but plants adapted to the specific conditions of the deep clay soil (grumusol). The conditions there involve water logging in winter and root tearing in summer as a result of soil shrinkage during desiccation. Many areas in this unit are almost devoid of active vegetation for a considerable part of the year. Overgrazing by herds and cutting of lignified plants for fuel led to the establishment of perennial unlignified and non-palatable plants such as Asphodelus ramosus and Urginea maritima.

9) Tragacanth vegetation of Mount Hermon

Snow covers much of the area of Mt. Hermon above 1,900 m a.s.l. for at least 3-5 months a year. The vegetation formation that is most prominent is composed of spiny, rounded, dense and small shrubs often known as "cushion-plants". Several species of these spiny shrubs belong to section Tragacantha in the genus Astragalus, known also as the genus Astracantha Podlech. Therefore, it is often referred to as tragacanth vegetation (Zohary 1973; Shmida, 1977a). Plants here suffer from two harsh seasons. Snow coverage and low temperatures in winter, and 4-5 months of dry summer in those areas with no snow accumulation. The west facing slopes become desiccated by the strong winds. The snow which is the principal water source in these elevations, is carried away by the winds and is accumulated on eastern slopes. Snow depth east of small ridges may vary from a few meters to dozens of meters in one season. The wind-facing slopes are covered by plant communities dominated by cushion-plants such as Astragalus cruentiflorus and Onobrychis cornuta. The principal companions here are Acantholimon libanoticum, A. echinus, and Astragalus echinus. Geophytes, annuals and other plants with soft stems grow inside the shrubs; there are only a few such plants in the opened area among the shrubs. This is probably because of some protection against wind, herbivores, and snow hazards that the cushion-plants supply.

The depth of snow accumulated at the eastern slopes is influenced by the local topography. When the snow melts in spring, there is a narrow belt of blooming plants that follow the wet soil at the snow margin. The most prominent of these are Romulea nivalis and Ranunculus demissus. Cushion-plants also grow on parts of the eastern slopes that are covered by snow in winter.

The valleys among the ridges here are commonly evolved as karst phenomena. Dolinas with fine-grained leached soil are a common habitat all over the peaks of Mt. Hermon. Snow-melt is the principal source of water in these dolinas and the soil is waterlogged for a long time. Polygonum cedrorum and its many dwarf and prostrate companions cover the soil of the dolinas.

10) Steppe vegetation

Semishrubs grow over most of the slopes and hills in the area that has 80-250 mm mean annual rainfall. The vegetation formation is often referred to as shrub-steppe. Monod (1931) named this pattern of distribution "mode diffus" as opposed to "mode contracte" where plants occur mainly in dry water courses (known as wadis). The distribution of steppe communities of the Judean desert and the Negev is highly correlated with rock and soil properties. In hard and fissured limestone and dolomite most of the rain water penetrates the ground and is accumulated in the soil at the fissures and crevices. The water is protected here from direct evaporation. Such rocks support semishrubs on the slopes even in areas with less than 50 mm mean annual rainfall. The most common dominant of these soils is Artemisia sieberi. Thymelaea hirsuta is the co-dominant in that part of the Negev close to the Mediterranean semisteppe bathas. Noaea mucronata is the co-dominant over large areas of the Judean desert and the Negev. Reaumuria negevensis is the co-dominant in the Central Negev Highlands where there is some chalk component in the limestone rocks. Gymnocarpos decander is the co-dominant in the northern Negev anticlines (i.e., the Sede Boqer area) where many small outcrops of fissured limestone occur. These plant communities are rich in semishrubs, geophytes and annual plants.

Soil that develops on clay sediments, soft chalk, marl, and loessial soils have a different moisture regime. Due to the high moisture holding capacity of the fine-grained substratum, rain water is absorbed by the upper soil layers. Much of this water is lost by direct evaporation from the soil surface. The small quantities

of sea salts in the rain water (about 8 ppm) accumulate in these soils (Yaalon 1963). In mature soils there is a NaCl-rich layer at the depth of maximal water penetration. This is also the rhizosphere of the perennials in these soils. The chalk and marl outcrops are typified by plant communities that are poor in species. In most communities there is only one semishrub species. There are areas where no plants grow in regular years and only in extremely rainy ones develop annual halophytes. The most common semishrub halophytes that dominates in this unit are Reaumuria negevensis, R. hirtella, Atriplex glauca, Bassia (Chenolea) arabica, and Salsola vermiculata. The annual xerohalophytes are the following: Pteranthus dichotomus, Salsola inermis, Spergularia diandra, Mesembryanthemum nodiflorum and Aizoon hispanicum.

The plant communities developing on uncultivated loess soils are also typified by dominance of one xerohalophyte. Haloxylon scoparium dominates in the relatively dry parts of the Negev, whereas Anabasis syriaca does in moister areas, and Peganum harmala in still moister loessial soils. Loess in wide wadis with a gentle slope receives much higher quantities of water than the slopes. There are patches where Hordeum spontaneum dominates in such wadis.

The most interesting vegetation in the area with shrub-steppes is found in crevices and soil pockets of smooth-faced rock outcrops and cliffs. Here water is accumulated from a large area into the few crevices. The amount of available water in the crevices is several times that of other soils in the same area. Many Mediterranean plants grow in crevices, at the foot of the rock outcrops, and in wadis that have such rocks in their catchment. It is assumed that they are relicts from periods when wetter climate prevailed in the Negev (Danin 1972; Shmida, 1977b, Danin 1999a,1999b). Among the dozens of relicts there are the following: Sarcopoterium spinosum, Narcissus tazetta, Sternbergia clusiana (grows also on Mt. Meiron, unit 1), and the maquis' vines Prasium majus and Ephedra foeminea.

11) Shrub-steppes with trees of Pistacia atlantica

Most of the area of this unit is covered by Artemisia sieberi steppes as described in unit 10. Trees are found here and there on rocky terrain above elevation of 800 m. P. atlantica, an Irano-Turanian tree (Zohary, 1972) is the most common tree species there. It develops in three principal rocky habitats (Danin & Orshan 1970). Dwarf trees that never flower but may be several dozen years old are confined to rock crevices. They are limited by the small size of their rhizosphere in the soil pockets. At the foot of large rock outcrops there are 4-5 m tall trees which may be situated a few dozen meters below the mountain top. The most spectacular trees are those at the wadis. Trees more than 10 m tall with even larger diameter are not rare. P. atlantica keeps germinating and establishing in the Negev, and in all the three habitats together, there are hundreds of seedlings, some of which are one or two years old and others a few dozen years old. When compared with the old large trees these may be regarded as "seedlings" that display the continuous reproduction of P. atlantica populations in the Negev. The number of large P. atlantica trees that were counted from aerial photographs in the Negev highlands is 1,400. The endemic almond Amygdalus ramonensis is even more rare. Its entire population is estimated to be of less than 200 specimens. Other rare arboreal plants of these highlands are Rhus tripartita and Rhamnus dispermus. The endemic semishrub Origanum ramonense and the endemic perennial herb Ferula negevensis are confined to the smooth-faced rocks of this area.

The steppes of the Central Negev Highlands become very spectacular in rainy years. A community of A. sieberi with Helianthemum vesicarium looks like a blooming garden. The colour diversity of H. vesicarium populations is very high; there are various lilac, white, and purple flowers with many transitional colours. These are accompanied by the spectacular Tulipa systola, T. polychroma, and Erodium crassifolium. In dry years there is not even one flower over huge areas.

12) desert vegetation

There is a gradual transition between the steppe vegetation, in the area with more than 80 mm mean annual rainfall, and desert vegetation in drier areas. Many Saharo-Arabian species prevail on slopes of the area with 70-90 mm mean annual rainfall. Within this area, edaphic conditions and microtopography are the most important factors affecting moisture regime and thus the distribution of plant

communities. Areas of fissured hard limestone are populated by communities of Zygophyllum dumosum and Gymnocarpos decander. These communities are floristically less rich than the steppe vegetation. On the soft rocks there are plant communities of the xerohalophyte semishrubs Suaeda asphaltica, Agathophora (Halogeton) alopecuroides, Salsola tetrandra and others. Their typical feature is that they are dominated by one semishrub that is hardly accompanied by any other semishrub.

In drier parts of the desert, vegetation develops mostly in a contracted pattern, i.e., in wadis. In most soil and rock types there is not sufficient moisture in the substratum of the slopes to support perennial vegetation. Hard and fissured limestone and dolomite support impoverished diffused communities of Zygophyllum dumosum on the slopes. When descending from the water divide into the wadi, the catchment area grows progressively. The wadi beds change according to the increasing erosive potential of the wadi's water; the amount of water penetrating the soil increases along the wadi course. The vegetation of the wadis changes along its course and each section that may be typified by dominance of one or two species is regarded as part of plant community. The other stands of the plant community appear in the neighboring wadis, in a similar section of the wadi. The general sequence of communities along wadis in extreme desert is the following: at the wadi top section there are annual species in rainy years; below it prevail short living small semishrubs, which are accompanied in rainy years by species of the former community and other companions. The third community is dominated by larger semishrubs that live from a few dozen to a few hundred years. In the fourth community 1-3 m tall shrubs dominate; they are accompanied by species of the previous communities and others. Acacia trees are the dominants of the first

tree community in the wadis. Of the three Acacia species in the Negev,

A. pachyceras (A. negevensis) develops at the highest elevations. A. raddiana prevails in the Acacia community at warmer sites, and A. tortilis is in the warmest sites (Halevy & Orshan 1972). Parts of the Acacia community belongs to unit 15, i.e., the Dead Sea and Arava Valleys. At a lower section of the Acacia unit in large wadis the underground water is closer to the surface and the dominant tree is

Tamarix nilotica.

There are dozens of semishrub communities along wadis of the Southern Negev. The most prominent are those of: Zygophyllum dumosum on step-like outcrops of hard limestone and dolomite in the wadi; Gymnocarpos decander prevails in wadi sections where the substratum is outcrops of flint, limestone, granite, or other magmatic rocks; Artemisia sieberi dominate in wadis with silty beds of gravel plains of the southern Negev north west of Elat; Haloxylon salicornicum dominates in sandy wadis; Reaumuria hirtella, Salsola tetrandra, Agathophora

alopecuroides, Anabasis setifera, and Haloxylon negevensis dominate in wadis on soft Chalk or marl. Anabasis articulata dominates in wadis which are similar to those of Artemisia sieberi but at a lower elevation or with less silt and more gravel in the substratum of the wadi channel. The principal dominant of the shrub communities of chalk and marl ground is Atriplex halimus. In the other soil types the shrubs are Lycium shawii, Retama raetam, and Ochradenus baccatus.

13) Sand vegetation

Each of the three main sandy areas in Israel is in a different climatic zone; the origin of their sand is also different. The Mediterranean coastal sands are the youngest and because of their coarse texture and unstable situation they support poor vegetation cover. Haluza and Agur sands are older and have finer texture and

denser vegetation cover. The sands of Rotem-Yamin plain, the Mamshit Valley and the valley between Yerokham and Dimona are derived from weathering of Tertiary sandstones and are composed of coarse sand and airborne silt. The sands of the Arava Valley are derived mainly from weathering of Cretaceous and Tertiary sandstones. There coarse sand is mixed with alluvial material of varying texture and support the Haloxylon persicum plant community (see unit 16). This vegetation unit resembles a vegetation formation of Central Asia and is discussed

separately.

The typical plant community of the coastal sand dunes along the Mediterranean sea is of Ammophila arenaria. This perennial grass is typical of sands all along the coasts of the Mediterranean and the Atlantic sea. It produces adventive roots from the internodes of sand-covered stems and grows above the sand cover. When exposed its roots die. At the wind shadow of A. arenaria, Artemisia monosperma

germinates. This is a desert plant that is adapted to the inferior moisture regime of the sand. An adult A. monosperma shrub resists sand coverage of its stems and exposure of its roots. The sand, trapped within the shrub and protected from wind erosion, builds up a mound. These mounds, also known as nebkas, biogenic mounds or phytogenic hillocks lead to sand stabilization. When sand movement ceases Ammophila arenaria dies and at the A. monosperma shade other plants establish that need and use the shade and the humus. In the moist environs of Caesarea amelioration of soil conditions (see description of unit 5) takes place

in a long process that leads to the development of soil which may support trees. At the southern coastal plain the climate is drier and the A. monosperma community does not become as dense as to influence dust trapping and the stable sand is covered by communities dominated by A. monosperma, Retama raetam, and Helianthemum stipulatum. In places suffered from sand erosion by wind the dominants are Scrophularia hypericifolia, and Moltkiopsis ciliata.

Stipagrostis scoparia dominates on mobile sand dunes of the Western Negev as in the Haluza and Agur sands in a similar way to A. arenaria in the Mediterranean

sands. Stable sand, in the first stages of stabilization, becomes populated with the perennial grasses Panicum turgidum and Pennisetum divisum. Old stable sand is populated with A. monosperma, Convolvulus lanatus, Deverra tortuosa, and Atractylis carduus. Airborne silt and clay that is trapped at the sand surface improve the moisture regime there and enable the development of microbiotic crust with filametous cyanobacteria as the principal component. This crust decreases sand mobility and promotes sand stabilization (Danin et al.1989, Danin 1996).

Large areas of sandy-loess soils at the northwestern part of unit 13 were cultivated by Bedouin in the past; they marked the boundaries of their fields by planting the large geophyte Urginea maritima. The border between Israel and Egypt is very conspicuous in the area of Haluza sands. Intensive grazing and trampling by Bedouin herds and cutting of lignified plants for fuel led to destruction of the

microbiotic crust. This interference promoted reworking and wind erosion of the

once stable sands on the Egyptian side of the border. This led to the striking border line between the two countries that can be easily seen from space (Fig….).

The sandy soils of the northeastern Negev are characterized by dominance of Anabasis articulata which is accompanied by various plants according to local environmental conditions. Thymelaea hirsuta which prevails in wadis on most soil types, grows in a diffuse pattern on unconsolidated sandstone between Yerokham and Dimona. One of the most prominent species that accompanies the A. articulata and T. hirsuta community is the rare Iris petrana. In Israel it grows only in the two

sandy valleys near Dimona. The A. articulata and Artemisia sieberi community is confined to those parts of the valley where large quantities of loess are mixed with the sand. Sand covers the ancient sandstone relief in the Yamin-Rotem plain. When protected from trampling, cyanobacterial crust develops here as well. No semishrubs grow on the sandstone outcrops; it is the lignified annual Anastatica

hierochuntica (rose of Jericho) that is confined to this habitat. When the exposed rock contains many pebbles, the dominant plant is Zygophyllum dumosum. Anabasis articulata dominates in sites where the sand cover is less than 1 m deep, and Calligonum comosum where the sand is more than 1 m deep. Calligonum comosum and Retama raetam grow along the wadis.

14) Oases with Sudanian trees

The Arava, Dead Sea, and Jordan valleys constitute the warmest zone in our area. Temperatures are much higher than in the neighboring areas at the same latitude. It is also the base of erosion, i.e., runoff water and underground water accumulate in it. Large springs have flown for hundreds of thousands years along the fault lines which bound this rift valley. Constant supply of fresh water and high

temperatures enabled thermophilous trees of Sudanian origin to establish in oases. The distribution of each tree is limited by its demands for high temperatures or resistance to low ones, and by its resistance to soil salinity. Several desert springs support the salinity resistant date palm, Phoenix dactylifera, that is accompanied

by Juncus rigidus (J. arabicus). There are growing evidences that such

spontaneous date palms could have been the progenitors of the cultivated date palms. Many Sudanian trees occur in En Gedi where fresh water springs flow at elevation higher than the level of the Lisan Lake (the precursor of the Dead Sea which existed between 70,000 and 11,000 years B.P., Begin et al. 1974). The following are some of these Sudanian trees: Calotropis procera, Moringa peregrina, Salvadora persica, Cordia sinensis, Ziziphus spina-christi, Ficus carica, Acacia tortilis, and A. raddiana. Several Sudanian species grow in Jericho and the large wadis west and north- west of it; however, the list of spontaneous Sudanian trees of this area is shorter than that of En Gedi. The relatively cooler temperature regime of this area may be responsible for this decrease in the number of tree species. The common trees of Jericho and its environs are: Ziziphus spina-christi,

Balanites aegyptiaca, Calotropis procera, and Ficus carica. These are the trees that prevail further north to the Jiftlik area at the oasis of Nahal Tirza (Wadi Fara'a). Plicosepalus (Loranthus) acaciae is a prominent Sudanian semi-parasite that grows on a few of these Sudanian trees.

Ziziphus spina-christi, the most cold resistant Sudanian tree forms savannoid vegetation further north (unit 7). The Acacia species are the most drought resistant trees and form savannoid vegetation along the Arava Valley (unit 15).

15) Desert savannoid vegetation

The amount of mean annual rainfall gradually increases in the rift valley from 30 mm near Elat to more than 150 mm north of Jericho. This quantity enables the growth of desert plants in most of the area. The amount of underground water is much higher than in the upper soil layers. Sudanian trees, the roots of which penetrate through the upper layers in wadis, may enjoy the high water table in an area poor in rainfall. Thus, some areas in the rift valley look like East African

savannas, but with Saharo-Arabian companions and with no perennial grasses. Of the Acacia species in Israel, A. tortilis is the most drought resistant and thermophilous one. A. raddiana demands more water and grows in cooler sites. The distribution of their desert companions is closely related to the edaphic conditions (Rudich & Danin, 1978). Anabasis articulata is the co-dominant in gravel plains with flint pebbles and with low quantities of sand. Haloxylon

salicornicum and Salsola cyclophylla prevail in wadis with sandy-gravelly substratum. Haloxylon persicum accompany the Acacia species in wadis with deep sand filling. Nitraria retusa, Alhagi graecorum, and Desmostachya bipinnata accompany the Acacia trees at the margin of large wet salines where upper soil layers are salty but underground water is not so saline. In the magmatic massif near Elat many Saharo-Arabian and Sudanian companions are found in wadis. Such are the following: Lavandula coronipifolia, L. pubescens, Pergularia tomentosa, Crotalaria aegyptiaca, Abutilon fruticosum, Tricholaena teneriffae, Stipagrostis raddiana, and Panicum turgidum.

16) Haloxylon persicum on sands

Deep sands in the Arava are covered by a sparse woodland of Haloxylon persicum. These are 2-4 m tall H. persicum plants with Haloxylon salicornicum and Calligonum comosum scattered among them. A similar formation dominated by related species of Haloxylon occupy large territory in Central Asia; it is called there "saxsaul", the vernacular name of the dominants. Much of the area that was once covered by H. persicum is intensively cultivated at present. Near wadis there are large H. persicum and Tamarix aphylla trees which germinated near the wadi and were covered since by 2-4 m sand mounds.

17) Swamps and reed thickets

Water logged soils on river banks support dense vegetation with low species diversity. We list hereby a few of the typical hydrophytic habitats. Phragmites australis, P. frutescens, Arundo donax, and A. pliniana, together with Rubus sanguineus, often form thickets near springs and on river banks that are difficult to pass. Typha dominguensis prevails in sites where fresh water (and even sewage water) flow slowly or is standing. A few Juncus species grow in places of high water table; the period when this water is exposed above the ground is short. A few Juncus species withstand saline soil. Date palm (Phoenix dactylifera), regarded by many researchers as a spontaneous species of this country, grows near many desert springs such as: En Ziq, En Aqev, En Zin, and En Aqrabim. These sites and many others are too small to be drawn in our map. It is suggested that during the domestication of date palms, such populations were used as a source.

Typical riparian trees are the following: Platanus orientalis that grows in the Upper Galilee; Salix acmophylla and a few Tamarix species occur in many rivers all over the country. Populus euphratica is the principal tree near the Jordan river and near a few desert springs.

18) Wet salinas

Salinas where salty water moisten the soil throughout the year occur along the Jordan, Dead Sea and Arava valleys, and near the Mediterranean sea at Akko-Zevulun Valley (Danin 1981). The geological structure along most of the Mediterranean coast of Israel leads to water flow from the land to the sea. At the Zevulun valley between Akko and Mt. carmel, the west-east rift valley enables underground flow of seawater inland and their mixing with the land's fresh water. The low areas of the salt marshes are populated by Arthrocnemum macrostachyum, Sarcocornia fruticosa, Limonium angustifolium, Atriplex portulacoides, and Tamarix tetragyna.

Sandy soils which cover the salt marshes support rich vegetation of halophytic and nonhalophytic annuals. Their coexistence here is possible due to leaching of the soil, in a non-homogeneous pattern, by large quantities of rain water. Before the draining of these salt marshes vegetation belts could be seen easily (Orshan & Zohary 1955). The salt marshes in the desert parts of the country differ by the scarcity of annuals there. In most years the soil is too saline to

enable the development of annuals. The prominent plants in the salt marshes of the desert are the following: Suaeda monoica, S. fruticosa, S. vermiculata, Arthrocnemum macrostachyum, Nitraria retusa, and Seidlitzia rosmarinus. Tamarix nilotica and other Tamarix species, which are highly resistant to salinity, thrive in desert salines. The largest continuous salt marshes are those in the southern Dead Sea area, and near Yotvata. There are no higher plants in the constantly wetted salty center of these salt marshes. A few plant communities

that are arranged in belts around the source of saline water can be seen in these two areas (Bourvine, 1963; Danin, 1983).

19) Synanthropic vegetation

The composition of vegetation in the areas that are intensively managed by man can be easily differentiated from that of the intact areas, or areas of small interference. The history of human activity in the levant is long, and according to Zohary (1983) we are now in the Neo-Segetal era. The most intensively cultivated areas along the coastal plain and the Esderaelon Valley (unit 19) are divided into three principal subdivisions; 19a are the cultivated areas where remnants of Quercus ithaburensis occur; 19b where the spontaneous trees are Ziziphus spina-christi; 19c is the area where both Z. spina-christi and Acacia raddiana can be found. Synanthropic species occur all over the country (Danin 1991a). Examples of synanthropic flora of specific habitats are listed below. For the last 20 years the road sides of the main highways are sprayed with herbicides. The main purpose is to prevent the development of winter annual plants. These can become a "fire bridge" between burning cigarettes thrown from passing vehicles by irresponsible persons and the area near the road. The herbicides used for this purpose are triasines that affect the young seedlings when emerging from the seed coat. Perennial and annual summer grasses germinate at the end of the winter when the herbicides have already disintegrated. Such grasses are the following: Hyparrhenia hirta, Dichanthium annualtum, Sorghum halepense, S. virgatum, Tricholaena teneriffae, Cynodon dactylon, Panicum maximum, P. capillare, and Paspalum dilatatum (Danin 1991b). Prosopis farcta and Alhagi graecorum which emerge from their perennial underground organs, start developing in spring and are not affected by the herbicides. When the use of herbicides ceases the first colonizers that invade to the opened space among the grasses are the wind-disperssed three Conyza species and Aster subulatus. These are of an American origin and arrived in Israel during the last 100 years. A few dozen adventive plant species that arrived in the country from afar have developed in human managed habitats. In all these habitats the primary vegetation was destroyed for a certain time and the area is open for colonization. Such habitats occur at the margins of agricultural areas, and on the sides of wide roads where rocky or stony material was laid on the local soil. In a similar way, building sites may harbour colonizers until the entire area is adequately managed.

Some of the wheat and barley fields of the Arabic farmers are cultivated and managed in the ancient farming methods. Many of the Biblical descriptions of the agricultural life can be observed in this style of farming. The weeds in the winter cereals are similar to those found in the area for a few millennia when these cereals were domesticated in our area. Lolium temulentum and Cephalaria syriaca have large seeds that are not dispersed when ripping. The entire plants are harvested with the cereals, and having seeds of a similar weight and size, they are not separated in the threshing site. They are then distributed together with the cultivated plants.

The weeds in the intensive and modern Israeli agricultural areas are different (Danin et al. 1982). The weed composition depends on the agrotechnical management and the type of herbicides used. The summer irrigated fields harbor species of the following genera: Amaranthus, Xanthium, Conyza, Eragrostis, Echinochloa, Chloris, and Paspalum. Abutilon theophrastii, Datura species, and Xanthium species that were not known in the dry farming, became noxious weeds in cotton fields. Orchards of oranges and other cultivated fruit trees harbor rather unique assemblage of weeds. These include wild and cultivated plants, the fruits of which are bird-dispersed. Birds that eat the juicy fruits and excrete the undigested hard seeds under the orchard trees. Thus, the following became established in orchards of the coastal area: several ornamental species of Asparagus, Prasium majus, Lantana camara, Morus alba, Melia azedarach, and Washingtonia filifera.

Apart from these there are plenty of alien species that are found in synanthropic habitats as well as local species that abound in these habitats and become synanthropic (Danin 1991a).

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