by Yevgeny SHEIN, Dr. Sc. (Biol.), Department of Soil Science, Lomonosov Moscow State University; Anna FEDOTOVA and Lyudmila YAKOVLEVA, Drs. Sc. (Biol.), Astrakhan State University; Vladimir PILIPENKO, Dr. Sc. (Biol.), Director of the Innovation Natural Science Institute of Astrakhan State University Talking about Astrakhan, a city in the upper delta of the Volga, invites the following associations in most people: fish, tomatoes, watermelons-the things this region is famous for. There are but few who know about complicated natural interrelations accounting for the biological diversity of this area and the significant role of soils in the life of the local flora and fauna. One of the Volga branches delta in summer. стр. 106 Map of Russia's Astrakhan Region: 1-shallows; 2-above-water plants; 3-wafer plants; 4-delta channels; 5-sea delta edge at the 18th cent., maximum rise; 6-sea delta edge in 1817; 7-sea delta edge in 1873; 8-numbers and boundaries of shallows in Volga coastal waters; 9-depth isolines. Back in 1978 the Volga delta was artificially divided into two parts by a dam. During high water periods its eastern piscicultural part is fully flooded: fish spawn on its wide plains, new generations of fish grow and then leave for the Caspian Sea. The western agricultural part is intersected by irrigation systems that bring water to grow watermelons and tomatoes. Vegetables are grown in a semidesert under a scorching sun with almost no precipitation in summer and the upper layer of soil heated to 50-60 ºC! It is impossible for plants to survive here without water; this water and soil particles brought in by the great river Volga from the north in fact determine the life pulse of these territories. PULSE OF FLOODPLAIN ECOSYSTEMS The geographical structure of the Astrakhan flood-plain formed on the Khvalynsk saline clays-deposits of the Caspian Sea (Khvalynsk Sea in Old Russia), is unique. Such clays form soils c ... Читать далее