The cause of Orumiyeh’s depletion has been disputed. Satellite observations of Orumiyeh’s surface levels show an overall decline of about 4 meters between 19, with an increase in water levels in the mid-1990s. The most obvious difference between the two images concerns the rocky outcrop near the image center. The Thematic Mapper on the Landsat 5 satellite captured these natural-color images of Lake Orumiyeh on Aug(top), and Aug(bottom). As the region’s arid climate evaporates the water, the salts crystalize along the shore. Because the lake lacks an outlet, those salts accumulate in the basin. Orumiyeh is fed by roughly 60 rivers and streams-some permanent and some ephemeral-that also deliver salts.
Lake Orumiyeh (also Orumieh or Urmia) in northwestern Iran is one of the world’s largest landlocked salt lakes, but it is shrinking.
Ephemeral rocky outcrop full#
Besides regular short-term dynamics, there are also long-term vegetation dynamics with cycles spanning several years.To download the full resolution and other files go to: /IOTD/view.php?id=76327&src=. Especially small inselberg and rock outcrop habitats are often affected by heavy fluctuations of their environmental and climatic conditions. Small-scale alterations of the ecological situation often result in a mosaic-like pattern of the plant communities. Three alliances can be distinguished: West African alliances Cyanotido lanatae-Afrotrilepidion pilosae and Spermacoco hepperanae-Afrotrilepidion pilosae, and an Atlantic Central African Oreonesiono testui-A frotrilepidion pilosae. They colonize gentle slopes and are often close to communities of the Drosero-Utricularietalia subulatae. Afrotrilepidetalia pilosae) are very widespread in humid parts of tropical West Africa. Mats of monocotyledonous plants (Afrotrilepidetea pilosae. It contains the Eriocaulo pumili-Ophioglossion gomezianum, which combines communities with short-lived plant species in small pools on rock outcrops and in shallow depressions over laterite, and the Genliseo africanae-Sporobolion pauciflori, which colonizes similar habitats but is geographically restricted to few mountains in Guinea, Sierra Leone and Liberia. The Dr oserò indicae-Utticularietalia subulatae (Drosero-Xyridetea) comprises ephemeral vegetation in rock pools and depressions over lateritic crusts. Plant communities from Atlantic Central Africa and West Africa are very distinct from a floristic point of view in an ordination, they are clearly separated. A classification of 43 partial data sets, based on 378 relevés, resulted in four associations and several rankless communities, grouped into four different classes (Drosero-Xyridetea, Afrotrilepidete a pilosae, Lycopodietea cernui and Microchloetea indicae). The first synopsis of herbaceous vegetation of seasonally wet or inundated habitats on rocks, inselbergs, mountain ridges and latentie crusts in several bioclimatic zones of tropical West Africa and Atlantic Central Africa is presented. Their vegetation is relatively uniform and differs from the surrounding vegetation. They are of great interest from a botanical point of view. Inselbergs, mountain ridges and latentie crusts are characteristic landscape elements in many tropical regions.
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