Semi-steppe Batha; Tragacanth Vegetation of Mt. Hermon

פורסם: February 21st, 2010 | עודכן: 25/12/19

1.3.8 Semi-steppe batha

The communities dominated by semi-shrubs at the boundary of the Mediterranean zone, where mean annual rainfall is 300-400 mm, are regarded as semi-steppe bathas. There are several communities dominated by Mediterranean plants such as [Sarcopoterium spinosum] (Fig. 1.3.42), which dominates bathas in more mesic parts of the country (Sect. 3.1). Others, such as [Artemisia sieberi] and [Noaea mucronata], dominate steppe areas in the Negev, Sinai, Jordan, and eastwards to Afghanistan. Many plants which play an important role in the seral communities in fallow fields at the center of the Mediterranean region grow here in their primary habitats, where no anthropogenic disturbances assist or facilitate their growth.

[Sarcopoterium spinosum], which becomes ethiolant and dies in the shade of trees and shrubs in the course of plant succession in maquis and forests (cf. 3.1), has no such competitors (Fig. 1.3.43). The impact of harvesting ants on the annual vegetation is prominent here as well as in the center of the Mediterranean territory (Fig. 1.3.43). During the past decade, the wide valleys among the hills covered by semi-steppe bathas have supported broad carpets of [Anemone coronaria] (Fig. 1.3.45). Hills subject to intense grazing and cutting for long periods of time support winter vegetation composed of non-lignified plants and others that are not palatable to goats and sheep (Fig. 1.3.46).

Fig. 1.3.42: Semi-steppe bathas on slopes of Mt. Amasa, southern Judean Mts. towards Arad Valley.

Fig. 1.3.43: Semi-steppe batha near Lahav. Prominent shrubs of Sarcopterium spinosum and the yellowis Euphorbia hierosolymitana. In the local valley herbaceous vegetation with nests of harvesting ants.

Fig. 1.3.44: The harvesting ants nest is recognized by dark colored and tall grasses and the presence of yellow-blooming Sinapis alba. Compare the size of a single Sinapis right of the nest with that of plants near the nest.

Fig. 1.3.45: A field covered by Anemone coronaria at a valley near Lahav. The white-blooming plants are of Diplotaxis erucoides prospering near an ant nest.

Fig. 1.3.46: An overgrazed semi-steppe batha in the Judean Desert near Mishor-Adummim. The lignified shrubs were cut and most other plants have been grazed by goats. Plants of Urginea maritime and Asphodelus ramosus, resistant to cutting and grazing, cover the entire slope.

1.3.9 Tragacanth vegetation of Mt. Hermon

The peaks of Mt. Hermon are covered by snow during a considerable part of the winter (Fig. 1.3.47). High-velocity winds hit the peaks and cause heterogeneous snow cover of the area, which influences the distribution of plant communities. The depth of snow differs significantly from the crests to the valleys between them (Fig. 1.3.48). The most prominent formation of vegetation developed on the windward slopes of the peaks, above 1,900 m. on Mt. Hermon, are shrubs that look like spiny cushions. This formation is also known as tragacanth vegetation (Figs. 1.3.49-1.3.50), a name derived from a large group in the genus [Astragalus], section Tragacantha (regarded at present as the independent genus Astracantha Podlech). Many species of this group (Figs. 1.3.49-1.3.51, 1.3.55-1.3.56) and of the genus [Acantholimon] (Figs. 1.3.52-1.3.53) are components of the cushion-plants formation throughout the Middle East. The spiny cushion seems to have some biological advantages which help it adapt to some of the elements of this habitat’s harsh conditions, among them cold winters with high-velocity winds, precipitation mainly as snow, dry summers, and extreme stress from grazing domestic animals. Because of the short growing season and this harsh environment, very few annual plants accompany the cushion plants. On the slopes in the wind shadow of small local ridges or crests, wind velocity is rather low. Consequently, snow accumulates there and covers the soil as a layer that may reach a depth of 10 m. for a few months. Water drains from the slopes of this area through karst systems, and not through wadis as in many other parts of the country.

Fig. 1.3.47: Majdal Shams and the snowy slopes of Mt. Hermon in the 1960s.

Fig. 1.3.48: Mt. Hermon at 2,200-2,300 m a.s.l. The snow is removed by strong winds from the crests and accumulates in the local valleys, where snow depth is high. The brown patches on the snow are of desert dust arriving via storms from the south and east desert areas.

Fig. 1.3.49: Wind-facing (towards west) slopes at 2,200 m, covered with spiny cushions of Astragalus cruentiflorus and Acantholimon species.

Several species of tragacanth [Astragalus] occur in areas which are far from Mt. Hermon and the Anti Lebanon mountains. [Astragalus bethlehemiticus] (Fig. 1.3.54) is a typical companion of steppes and rock vegetation in the shrub-steppes of the Negev Highlands and of southwest Jordan; [Astragalus echinus] (Fig. 1.3.55) is a representative of this group at the high elevations of southern Sinai.

Fig. 1.3.50: Astragalus cruentiflorus on a slope suffering from intense winds.

Fig. 1.3.51: Astragalus cruentiflorus blooming. At the lower left fertile hairy calyces remain on the inflorescence axis for a long time.

Fig. 1.3.52: Acantholimon libanoticum.

Fig. 1.3.53: Acantholimon ulicinum in bloom. The shrub part where leaves are green is restricted to the upper 1-2 cm. Leaves are hard, needle-shaped and spiny.

Fig. 1.3.54: Astragalus bethlehemiticus. After blooming, fruits included in the fertile hairy calyx remain on the inflorescence axis for a long time.

Fig. 1.3.55: Astragalus echinus. The top left entire shrubs, at the top of Gebel Umm Shomar, S Sinai; low left and right at Mt. Hermon.