Weathering Patterns from the Distant Past; Nari with Rhamnus lycioides and Pistacia lentiscus
Weathering Patterns from the Distant Past
Nari rocks near Sdot Micha carry on their south-facing parts evidence of biogenic weathering that took place under a much more arid climate than that of the present. Weathering patterns of pits and channels typical of deserts are presented in Figs. 18.1.10 and 18.1.11. They testify to a long period of ca. 100 mm mean annual rainfall (it is 400 mm there at present).When the climate became moister, denser vegetation developed, trapping air-borne dust, and a soil-protecting layer developed. Being covered, the desert weathering patterns survived to the present day. Destruction of the maquis vegetation brought about soil erosion leading to the exposure of the desert weathering patterns. Dark microorganisms covered the rock. A white band of newly exposed Nari is prominent in Fig. 18.1.11. Some of the weathering depressions of the past function as sites suitable for the establishment of plants discussed here (Fig. 18.1.12).
Mosses penetrate the Nari rocks
The water-holding capacity of the rock layers below the crust is high, and when exposed, in depressions, supports mosses (Figs. 18.1.6, 18.1.12-18.1.15). These trap dust and together with their dead parts form a kind of humus. Water passing through this medium becomes a more efficient dissolving agent than the rain water. The depressions with mosses become deeper and larger and reach a point at which water reservoirs in the depression enable a successful growth of annual plants (Figs. 18.1.12-18.1.16). As the volume of the depression grows (Fig. 18.1.17), additional species and individuals of annual plants may develop. As time passes, perennial plants establish themselves in the existing depressions. Micromeria myrtifolia is one of these pioneer rock plants (Fig. 18.1.18). Rock dissolution by plants such as M. myrtifolia extends the size of the free rhizosphere in the upper Nari and plant species diversity increases; examples are Chiliadenus iphionoides, Hyparrhenia hirta, and Narcissus tazetta (Fig. 18.1.19). Establishment of several H. hirta plants in several depressions is possible as well (Fig. 18.1.20). Chiliadenus iphionoides (Figs. 18.1.21, 18.1.22) is a typical rock plant (lithophyte) that may germinate in small depressions and rock crevices, sending roots into the rock, penetrating deeply and dissolving rock parts that are in contact with the roots. It thus prepares micro-habitats that are suitable for its companions. The vegetation class of the rocks in Israel and surrounding countries is named after C. iphionoides (Danin & Orshan, 1999). Old Nari outcrops support additional lithophytes near C. iphionoides. Such as: Majorana syriaca (Fig. 18.1.23), Micromeria fruticosa (Figs. 18.1.24, 18.1.25), Stachys palaestina(Fig. 18.1.26), and Teucrium capitatum (Fig. 18.1.27).
Rhamnus lycioides and Pistacia lentiscus
Old and expanded soil pockets enable the germination and establishment of shrubs and trees. Rhamnus lycioides is the common, prominent shrub in the Shefela (Figs. 18.1.28, 18.1.29). Following the establishment of the first shrubs, the number of shrubs per rock outcrop increases in the expanding rock crevices (Fig. 18.1.30). R. lycioides has lignified roots that grow and expand within the rock, leading in many cases to the breakdown of the rock and the opening of wide and deep fissures (Fig. 18.1.32). Large crevices contain an increasing amount of soil enabling the establishment of maquis plants that are not typical lithophytes, e.g. Pistacia palaestina (Figs. 18.1.31, 18.1.32) and Pistacia lentiscus (Fig. 18.1.32). A P. lentiscus shrub that symbolizes the final stages of the succession and deterioration of the Nari rocks is present near Sdot Micha (Figs. 18.1.34, 18.1.35).
The north-west slopes of the hills near Sdot Micha support maquis rich in P.palaestina (Fig. 18.1.36), Quercus calliprinos, and Styrax officinalis. Also here the boundary of the lignified vegetation with the herbaceous vegetation passes at the edge of the Nari outcrops.
- Danin, A. and Orshan, G. (eds.) 1999. Vegetation of Israel. I. Desert and coastal vegetation. Backhuys, Leiden, 341 pp.
- Itkin, D., Geva-Kleinberger, A., Yaalon, D. Shaanan, U. and Goldfus, H. 2012. Nari in the Levant: historical and etymological aspects of a specific calcrete formation. Earth Sciences History 31(2): 210-228.
- Wiederl, M., Sharabanil, M. and A. Singer, A. 1993. Phases of calcrete (Nari) development as indicated by micromorphology. In: A.J. Ringrose-Voase and G.S.Humphreys (eds.) Proceedings of the IX International Working Meeting on Soil Micromorphology, Townsville, Australia, July 1992. P. 37-49.