Semi-Steppe Bathas; Steppe Vegetation
2. Semi-steppe bathas
Semi-steppe bathas are formations including dwarf shrubs of Mediterranean origin (such as Sarcopoterium spinosum) – and steppe origin (such as Noaea mucronata and Artemisia sieberi; Fig. 8.1.16). The vegetation class developed here is the Ballotetea undulatae. These bathas are confined to areas where mean annual rainfall is 250-350 mm.
Phlomis brachyodon (Fig. 8.1.17) is a diagnostic species of these bathas. They are regarded as a primary habitat of seral plants of the old field succession such as S. spinosum and Calicotome villosa. When the agricultural fields that replaced maquis of the past were abandoned, Mediterranean bathas started the long process of natural rehabilitation of the maquis. S. spinosum and C. villosa could invade the fallow fields from the seed banks of the semi-steppe bathas. In the 1960s large areas of semi-steppe bathas on hard limestone could be observed along the Jerusalem – Jericho road. Restructuring of this road and its edges prevents access to such areas at present. Bedouin settled near the road and make good use of the S. spinosum shrubs and its companions. Remnants of semi-steppe bathas may be seen along the slopes between the town Ma’ale Adumim and its industrial park. The lignified plants there were cut for fuel and the non-poisonous plants were consumed by the herds.
Poisonous and thorny plants have a biological advantage here. Consequently, it is hard to recommend a specific site for botanical observers to stop and learn about the semi-steppe bathas and we shall move on to the next vegetation belt.
3. Steppe vegetation
As we continue eastwards the vegetation class Ballotetea undulata is replaced by the steppe vegetation – Artemisietea sieberi. The rocks in much of the area are chalk and marl, which are soft rocks. The rain water that soaks into the upper soil-rock layers evaporates and leaves rain water salts in the soil (8 mg per liter). For tens of thousands of years the soil has been enriched by salts and only plants resistant to salinity may develop (halophytes). Many halophytes belong to the Chenopodiaceae and each of them prevails in a specific area and forms monospecific associations. Salsola vermiculata is the least resistant to salts and prevails on the slopes near Kfar Adumim, Mishor Adumim and the Inn of the Good Samaritan at the top of Ma’ale Adumim (Figs. 8.1.18, 8.1.19). From here and eastwards the slope direction has a strong impact on the vegetation. The south- or the south-west facing slope supports mainly dwarf shrubs; however, the north- and north-west facing slopes have a carpet or uninterrupted lawn-like cover of the grass Poa eigii (Eig’s meadow grass, Fig. 8.1.19). The plant escapes the harmful stress of the grazing herds by being low (3-4 cm, Fig. 8.1.20). The meadow grass carpets sprout shortly after the first winter rains and thus emphasize the difference between northern- and southern slopes (Figs. 8.1.18, 8.1.19). The meadow grass plants grow slowly above the air-borne dust which becomes trapped among their green or dry leaves (Fig. 8.1.20).
The underground parts which were alive and functional are seen at a relatively deep part of the soil profile. Liverworts, mosses, and soil lichens grow in the spaces among the active tufts of meadow grass (Fig. 8.1.21), and grow above the dust trapped in the microbiotic crust. The efficiency of dust trapping and the growth above it is revealed in the slopes morphology. The north-facing ones are smooth, with 50-100 cm deep fine-grained soil whereas on the south-facing ones the rocks and stones are exposed on the rugged surface. In rainy years annuals such as Erucaria rostrata germinate in empty spaces among the meadow grass carpets, coloring the slopes with their wealth of flowers (Figs. 8.1.22, 8.1.23). Shrubs of Salsola vermiculata send their roots down into saline soil layers where there is no competition from other plants. Salts absorbed in the Salsola body are returned to the soil surface in the drying and falling leaves and stems. The soil below the shrubs becomes saline (Fig. 8.1.24) and hence devoid of non-halophytic plants. The result of this salts recycling is clearly evident and may be seen from afar in other halophytes as well. Reaumuria hirtella (Fig. 8.1.25) belongs to the Tamaricaceae, which have many salt-secreting species. Their special salt-glands on leaves and young stems (Fig. 8.1.25, right) excrete concentrated salty solutions which crystallize in the dry desert air. Many areas that were populated by R. hirtella have been disturbed by human activity. These days it is hard to lead the interested observer to areas dominated by R. hirtella near highway No. 1.