Shrub and semishrub deserts in the Caspian region and western Turan

摘要

Shrubs and semishrubs give peculiar appearance to temperate deserts of Eurasia. Ecology of these species which are widespread on the plains between Caspian and Aral Seas is described. The desert shrubs and semishrubs were divided into 4 ecological groups: petrophytes, psammophytes, halophytes, and eurytopic shrubs and semishrubs. Petrophytes (shrubs Caragana grandiflora, Rhamnus sintenisii; semishrubs Astragalus turcomanicus, Salsola arbusculiformis) grow exlusively on stony-gravelly shallow soils developed over different rocks, such as limestone, sandstone, chalk (with the exception of Tertiary carbonate clays). Psammophytes (shrubs Calligonum aphyllum, C.caput-medusae, C.leucocladum, Haloxylon persicum; semishrub Astragalus karakugensis) are found only on sandy soils and sand massifs. Halophytes (shrubs Nitraria schoberi, Tamarix elongata, T.gracilis, T.hispida, T.hohenackeri, T.laxa, T.ramosissima) are associated with saline soils of different texture. The eurytopic species occur in wide range of habitats: Calligonum junceum and Haloxylon aphyllum are the common species of salt-laden sands and soils with strong concentration of gypsum; shrubs Atraphaxis replicata, Salsola arbuscula, Calligonum junceum, Haloxylon aphylium, and semishrubs Convolvulus fruticosus, Krascheninnikovia ceratoides grow on limestone, sandstone, chalk as well as on sands being the indicators of shallow sand layers.