South Iranian Rocky Upland Formations
Upland vegetation can be found on the Pliocenic arenaceous rocks of the Kech Band, Gockprush Band, Jiwani and the hills near Tump and Mand. The extreme temperatures prevent the development of rich vegetation and it largely consists of scattered trees of Dalbergia sissoo, Gymnosporia senegalensis and Tamarix indica and shrubs of Astragalus stocksii, Dodonaea viscosa, Grewia tenax, Vitex negundo and Zygophyllum eurypterum. The dwarf palm Nanorrhops ritchieana colonizes dry riverbeds. At ground level below various trees annuals such as Notoceras bicorne and the endemic or near endemic Viola makranica (Violaceae) form ephemeral cover on some of the richer soils. Perennial herbs are largely confined to rock crevices and gravelly slopes. These may include Cleome oxypetala, Euphorbia osyridea, Otostegia persica and Salvia aegyptiaca. In small crevices of a ravine in Kech Band, Pycnocicla bashagardiana (family?) has been recorded. This species appears to be endemic to Iran and Pakistan. The most natural upland vegetation occurs on the promontories of Gwadar and Ormara. Here the territory has been under military occupation and so no exploitation of the vegetation has been allowed. The most typical species of these protected areas is Commiphora wightii, a spiny, creeping tree. The ground layer on gravel soils includes the grasses Enneapogon brachystachyus, Lasiurus scindicus and Tricholaena teneriffae, while rock crevices provide habitat for the climbers Capparis cartilaginea, Pentatropis spiralis and Pergularia tomentosa. Where rocky debris prevails chamaephytes and hemicryptophytes such as Cleome brachycarpa, Commicarpus stenocarpus, Grantia aucheri, Launaea oligocephala, Pluchea arguta and Sphaerocoma aucheri become the main species. In the sheltered valleys small thorny trees such as Gymnosporia senegalensis and Ziziphus nummularia occur and in the wet season ephemeral like Aizoon canariense, Asphodelus tenuifolius, Aristida adscensionis, Geranium mascatense and Reichardia orientalis make an appearance for a short time. On the slopes of Kech Band scattered stands of Pistacia khinjuk are considered to be a relict of once more extensive montane vegetation.
South Iranian Silty Alluvial Plain Formations
Most of the flood plains support a thick covering of fine silt. Good examples can be found in the wide flood plains of the Dasht River and its tributaries. Here the dominant species are Capparis decidua and Prosopis cineraria. Unfortunately the latter has often been over exploited for fuel or for building material. In fact exploitation of this species has contributed to the desertification of the area. Capparis decidua is well adapted to the dry conditions with its thick stem and lack of true leaves. Other species include Calligonum crinitum and Indigofera oblongifolia. Along river edges, the deep-rooted perennial grass Desmostachya bipinnata often stabilizes the banks. During the wet season these plains can become partially covered with ephemerals like Asphodelus tenuifolius, Astragalus eremophilus, Euphorbia serpens, Farsetia heliophila, Heliotropium remotiflorum, Malva parviflora, Plantago amplexicaulis and Trigonella uncata.
South Iranian Dry River Bed Formations
Most of the rivers, such as the Rakshan in the Panjgur Valley and the Kech and Nihing rivers in the Kech Valley are dry for most of the year. The vegetation that colonizes these dry riverbeds is therefore scattered throughout much of the region. It largely consists of thorny trees, shrubs and perennial herbs with well-developed root systems. Typical species in the lower levels include Nerium oleader, Rhazia stricta, Saccharum ravennae and Zygophyllum propinquum. On elevated ledges the characteristic species are trees such as Acacia hydaspica, Salvadora oleoides, Ziziphus nummularia, and shrubs like Lycium edgeworthii and L. shawii. Several species of Tamarix, such as T. aphylla, T. indica and T. stricta, can also form dense stands here, but widespread in broad river beds are various draught adapted, fleshy-leaved perennial such as Commicarpus stenocarpus, Grantia aucheri and Pteropyrum aucheri.
South Iranian Hydrophytic Formations
Because of the aridity of the area hydrophytic vegetation is limited to oases, channels and permanent streams. The latter can be found, for example, in the piedmont area near Pidarak. Here the bulk of the vegetation is composed of Cyperus laevigatus, Eleocharis geniculata, Fimbristylis diphylla, Scirpus maritimus and Typha domingensis. Mesotrophic waters are indicated by the presence of Najas marina, Potamogeton nodosus and P. pectinatus.
South Iranian Saline Flat Formations
Saline flats are common on the coast in ancient lagoons such as Jiwani, Kalmat and Pasni, and in inland depressions such as Gabd and Parom. They usually have a very hard saline crust in the dry season that becomes muddy during the wet season. Not surprisingly much of these areas are devoid of vegetation and the high salt content limits the vegetation to salt tolerant species (halophytes). These are mainly members of the Chenopodiaceae like Halocnemum strobilaceum and Suaeda fruticosa and halophytic members of the Poaceae like Aeluropus lagopoides, Halopyrum aculeatum and Urochondra setulosa.
South Iranian Sand Dune Formations
In certain places such as the Pasni areas the shifting sands are virtually devoid of vegetation. Only specialized plants like the creeping sand binding Aerva javanica, Citrullus colocynthis, Cyperus arenarius and Heliotropium bacciferum are able to grow well in this environment. They also help to stabilize the sand. Other species may include Calotrophis procera (which is avoided by grazing animals due to its sour, milky secretions), and the creeping annual Neurada procumbens, which helps its dissemination by producing spiny fruit that cling to animal fur. In the more stabilized dunes the endemic Convolvulus cephalopodes (Convolvulaceae) may be encountered, which is confined to South Iran and the Makran.
Further information required.
References
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