Nicola Arndt und Matthias Pohl - Neobiota

die Gesetzmäßigkeiten ihrer Breiten- und Längenerstreckung sowie -differenzierung dargestellt.
Dominierende und kennzeichnende Arten der einzelnen Formationen sind: Stipa tirsa, S. zalesskii,
S. anomala, S. ucrainica, S. capillata, S. lessingiana und S. sareptana.
Die Differenzierung der Wüsten- und Steppenvegetation in Unterzonen, Formationen, Standortstypen,
Gesellschaften und geographische Ausbildungen mit Angabe der jeweils kennzeichnenden Arten ist in
Übersichtstabellen dargestellt.
1 Introduction: which desert and steppe vegetation types occur in Europe
In Europe deserts and steppes are concentrated in the south-east. The boundary between the Eurasian
steppe zone and the Sahara-Gobian deserts coincides approximately with the limit between the areas
of light-chestnut and brown soils and runs in the Caspian Region along the Kuma River (Cis-
Caucasus), then to the north along the Eastern Jergeni up to 48° N and along this parallel to the east.
Desert vegetation on the Caspian and Turanian plains is represented by communities of xerophilous
and hyperxerophilous (drought resistant), micro- and mesothermic (frost resistant) plants belonging to
various growth forms, mainly dwarf semishrubs, semishrubs, shrubs, semitrees and also perennial and
annual herbs. Among the perennial and annual herbs a significant role belongs to ephemeroids, longvegetating
and short-vegetating (ephemeral) annuals (KOROVIN 1961, RACHKOVSKAYA et al. 1989,
SAFRONOVA 1996).
The dominating life form is dwarf semishrub. Communities of dwarf semishrubs of the genus
Artemisia subgenus Seriphidium (Asteraceae) and of the genera Anabasis, Salsola and other
Chenopodiaceae are distributed in various habitat types, including plains and hill slopes, on clay,
loam, sandy-loam, debris and stony soils, on sand, takyrs and solonchaks 1 .
Shrub communities with species of the genera Atraphaxis, Calligonum, Caragana, Ephedra,
Haloxylon, Salsola, etc., and semishrubs (Astragalus, Convolvulus, Krascheninnikovia, Salsola, etc.)
are distributed in habitats with more favourable moisture conditions. Within the limits of the desert
zone such habitats are represented by sand (with low evaporation because of low water-absorbing
capacity and suboptimal capillary action of soil water), stony-gravelly substrates of various lithology,
condensing water, and solonchak depressions with high level of ground water available to plants.
On sand, sandy and stony-gravelly soils, long-vegetating (Stipa, Agropyron) and short-vegetating
(Poa, Catabrosella) grasses often dominate in plant communities.
Steppe plant communities mainly consist of perennial, more or less xerophilous, microthermic (frost
resistant) herbaceous plants, mostly bunchgrasses. Species of the genera Stipa, Festuca, Agropyron,
Koeleria, Cleistogenes, Helictotrichon, etc. predominate. In different ecological environments
communities are formed by tufted sedges (Carex humilis, C. pediformis), onions (Allium spp.), herbs
(of the genera Galatella, Crinitaria, Tanacetum, etc.), dwarf semishrubs (of the genera Artemisia,
Thymus, etc.) and shrubs (of the genera Amygdalus, Spiraea, Caragana, etc.) (LAVRENKO 1940, 1956,
LAVRENKO, KARAMYSHEVA & NIKULINA 1991).
1
Takyr – thin desert soil, mainly loamy, with dense and smooth surface cracked into polygons.
Solonchak – hydromorphic soil of steppe and desert zones characterized by high concentration of water-soluble
salts in the surface layer forming salt efflorescences.
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