pondelok 3. januára 2011

Paleofloristic and paleofaunistic analysis of Dudváh River oxbow and implication for Late Holocene paleoenvironmental development...

Pišút, P., Břízová, E., Čejka, T., Pipík, R. 2010: Paleofloristic and paleofaunistic analysis of Dudváh River oxbow and implication for Late Holocene paleoenvironmental development of the Žitný ostrov Island (SW Slovakia). Geologica Carpathica, 2010, 61 (6): 513-533.


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Abstract: Žitný ostrov, the largest island of the Danube River (SW Slovakia) was formed to its present-day shape in the Neoholocene period. As a result of increased flood and geomorphological Danube river activity dated to 1378-1528 AD, the lower Dudváh River was abandoned and its alluvium became a part of the Žitný ostrov. Study of Dudváh terrestrialised palaeomeander by means of pollen and macrofossil analysis provides new information about the palaeoenvironments of the Danube Plain. Meander under study was cut-off during the Sub-Boreal period when the land was mostly covered by oak-dominated mixed forest with a notable high frequency of Fagus and Abies. At low-lying depressions, Alnus glutinosa have formed typical alder carrs. The largest decline of the mixed forest occurred during the Sub-Atlantic period. Until the mid-19th century the region was strongly influenced by shallow groundwater and periodical floods, as reflected by pollen of aquatics and marsh species. Amongst non-arboreal taxa, pollen of Cyperaceae, Brassicaceae/Cuscuta, Poaceae and Apiaceae prevailed. Local successional changes started with i. stage of abandoned oxbow still with influx of moving water, poor in both macrophytes and molluscs, ii. shallow eutrophic oxbow lake with slowly flowing or stagnant water overgrowing with aquatics (Ranunculus subgen. Batrachium, Potamogeton sp., Ceratophyllum demersum etc.) abound with molluscs, iii. an open marsh dominated by Cyperaceae (mainly Carex riparia) with Atriplex prostrata, supporting diverse molluscan and Ostracod fauna. Present-day habitat is a result of landscape changes, which have been associated with draining, intensified agriculture, ruderalisation and spread of invasive species.