Wood Debris in Rivers - One of the Key Factors for Management of the Floodplain Forest Biotope of European Importance
The article deals with analysis and management of wood debris accumulation in the Morava River within the Special Area of Conservation Litovelske Pomoravi (Czech Republic). Wood debris creates interference of interests between nature conservation (requirements for keeping wood debris in the stream) and foresters as well as water managers (requirements for removing wood debris from the flow area of the river). Based on the presented analyses, there was a set of wood debris management measures proposed in Litovelske Pomoravi in order to respect dynamics of fluvial succession series of floodplain forest biotopes, which are included in the Natura 2000 system.
Succession and the Development of Alluvial Communities After a Flood in 1997
This paper details a ten-year period in the development of floodplain biotopes after a disastrous flood in 1997 at three sites on along the Spojená Bečva River in the Zlín and Olomouc regions, Czech Republic. Two of the sites are located on gravel bars, whilst the third site is located on a bank characterized as bare bed flysch sediments uncovered after a flood in 1997. After the flood, the previously homogeneous alluvial environment changed into a varied mosaic of biotopes with renewed conditions for the development of willows (Saliceta fragilis inferiora) and stands of Ulmi-fraxineta carpini superiora and Alni glutinosae-saliceta superior. A detailed study of the vegetation at the selected sites was conducted annually from 1998-2002, and in 2008, using 10 m wide transects oriented perpendicular to the river. The obtained data, including phytocoenological records, were compared with the vegetation communities ten years earlier and during the examined time interval. The dependence of particular types of biotopes on site conditions was described.
In total, we identified and located 14 types of biotopes, completed 58 relevés, and found 245 species. The results show that succession is faster at moist sites with fine sediment in Rybáře and slower at drier sites without fine sediment in Lhotka nad Bečvou and Choryně. The flooding of the floodplain forest was not destructive for most species outside the flood channel. Between 2004 and 2006, short-lived and segetal species retreated. The dominant species are Phalaris arundinacea, Urtica dioica, Echium vulgare, and Artemisia vulgaris. Invasive neophytes included Reynoutria japonica, Solidago canadensis, Impatiens glandulifera and Robinia pseudoacacia.
The results obtained through this project can serve as a valuable foundation for decisions regarding nature conservation.