The modern state of the ecosystem in the Volga River delta ecotone and dynamics of the changes in water availability conditions

We prove that an abrupt amount of water-soluble salts in soils occurs due to rapid increase in heat provision under decrease in precipitation amount for the period with the temperatures above 10°C (under the integrated index of territories aridity, the G.T. Selyaninov coefficient is up to 0.3 or les...

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Bibliographic Details
Published in:IOP conference series. Earth and environmental science 2019-11, Vol.381 (1), p.12092
Main Authors: Valov, M V, Barmin, A N, Eroshkina, O S, Probst, E N
Format: Article
Language:English
Subjects:
Aquatic ecosystems
Aquatic plants
Aridity
Calcium
Calcium ions
Chlorides
Foliage
Forbs
Landscape
Low level
Magnesium
Moisture content
River flow
Rivers
Runoff
Salinization
Salts
Soil salinity
Soil water
Soils
Toxicity
Water availability
Water content
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Summary:We prove that an abrupt amount of water-soluble salts in soils occurs due to rapid increase in heat provision under decrease in precipitation amount for the period with the temperatures above 10°C (under the integrated index of territories aridity, the G.T. Selyaninov coefficient is up to 0.3 or less). Based on the results of investigations from 137 model sites at the Volga River delta in the years with water availability contrast conditions (2014 and 2015 are years with little water and 2016 and 2017 are water-abundant years), we indicate a decrease in the volume of river runoff according to the landscape-ecological complex of soil-plant cover. We also show the toxicity level due to the increase in toxic Cl-, Na+ and Mg2+ under simultaneous decrease in the content of SO42- and Ca2+ ions. Moreover, there is a change in soil salinization type from chloride-sulphatic to sulphatic-chloride, which directly affects plant cover: total biomass and foliage cover decrease on all deltoid landscapes of high levels, the participation of sedge and herbs decreases, and role of forbs increases. These processes are blocked due to the rise of the subsequent conditions of abrupt water availability and move back. The greatest and the most rapid changes are observed within particularly extended alluvial natural boundaries of low level in the vegetation classes Phragmitetea R. Tx. Et Preising 1942 and Bolboschoenetea maritime Vicherek et R. Tx. 1969 ex R. Tx. et Hulb. 1971 at the level of associations and types.
ISSN:1755-1307
1755-1315
DOI:10.1088/1755-1315/381/1/012092