XVI International Botanical Congess

Digression of various degree is observed in deserts and steppes zones. Mild digression increases to 10% while in Mongolia and Middle Asia (Karakum) digression reaches 30-50% severe pasture digression is found in Northern Africa (High plateau of Algire). Study of grazing impact upon vegetation in dry steppes and semideserts has shown that change of digression stages is of same manner from North Africa to China. Similarity of succession reveals throughout in change of climax grass coenoses by secondary rather densily located Artemisia communities and later on by coenoses of annuals (or rarely of some perennials). When grazing sheep the following stages of successions were found: middle digression (Artemisia), strong digression (Poa bulbosa, Ceratocarpus) and over-strong digression (Peganum etc.) Ass. Artemisia are digressive in North Africa, Turkey, Iran (A. herba alba), in N. W. Caspian region (A. lerchiana), in Mongolia (A. frigida). They have arisen after vanishing of the climax coenoses (ass. Stipa, Agropyrom), which existed there under normal (moderate) shepherding conditions. My investigations which I have been doing for 44 years allowed me to draw a conclusion that North-Western (near) Caspian region is wrongly regarded as a desert zone. The fact that small semishrubby species (Artemisia) occur here gave rise to considering N. W. (near) Caspian region as a desert. But coenoses with ass. Artemisia are not climax ones, they have appeared as a result of digression when there was an intensive shepherding. Hence N. W. caspian region should be referred to the steppe and not to the desert. Turan desert (Middle Asia) reaches only the Emba river mouth, but the desert zone does not cross Emba river. Wrong organization of pastures usage leads to antropogenic desertification and deterioration.