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Biodiversity of standing floodplain waters and processes of its formation and preservation
Pithart, David
Water chemistry and planktic communities in the naturally eutrophic alluvial waters in the Lužnice floodplain have been studied. The floofplain waters are naturally eutrophic, with strong vertical physico-chemical gradients and oxygen depletions at the botom. Small pools and backwaters of this type have unique phytoplankton structure. Prevailing dominance of flegellates, namely Cryptophyceae, and low proportion of green chlorococcal algae and Diatoms, and almost absence of Cyanophyceae are very unusual for such eutrophic waters. Flagellate dominate thanks their ability to keep the vertical position in a permanently light limited conditions (resulted from poorly mixed water columns and intensive shading of water surface by vegetation). Floodplain geodiversity play crucial role, determining morphology and location of pools and backwaters, their exposition to flooding and inflows of underground water. Terrestial vegetation effects light exposition, leaf litter.
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Current status of nature protection and management in Lužnice floodplain
Montagová, Martina ; Pithart, David
Lužnice floodplain has been preserved in a semi-natural state in a cca 25 km long section located between the state border and the town of Suchdol n L. Meandering river is surrounded by pools and oxbows, which are flooded several timeas a year. Most of the area is now the subject of nature protection. Microorganisms (Algae), water plants, birds and other wetland biota found a refungium here. Biodiversivity is maintained by river activity and mosaic structure of the landscape, formed by e pastures and wet forests. This character of landscape is now endangered by ceasing of meadow management, hence, the large parts of floodplain are now under the succesional stages leading to the wet forest in the decrease of overall biodiversity.
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Natural flooding in Lužnice floodplain - an holistic approach
Pithart, David ; Montagová, Martina ; Hartvich, P. ; Černý, R. ; Prach, K.
Natural flooding was analysed in the Lužnice River floodplain in a holistic approach. Benefits of natural flooding can be summarised as folows: 1. Water retention is increased due to the soil absorption, evapotranspiration, filling of oxbows, pools and natural depressions and finally the space between the river terreces. Real flood event are analysed here in terms of water distribution among these processes. 2. Natural flooding reduces the loss of ionts from the watershed by flowing the river outflouw and loss of carbon loss by slowing the decomposition processes. 3. Flooding creates and maintains floodplain geobiodiversity by re-forming of floodplain subsystems and differentation of its impact on these subsystems. For these reasons, maintaining and enchenging of natural flooding seems to be a prerequisite of sustainable management of riverine landscape.
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