Results of floodplain forests protection in the Uroczysko Warta, the Wielkopolska Region, Poland

The Uroczysko Warta is one of the most important riparian forest areas in Poland. The construction of the Jeziorsko reservoir resulted in changes in the Warta river hydrological regimes. This in turn led to a reduction in the floodplain area and flooding frequency, which as a consequence has had a dramatically detrimental effect on the floodplain forests in that wilderness. Riparian forests are among the richest and most beautiful forest ecosystems. Unfortunately, river regulation and flood control measures result in their degradation. In Poland only 0.2% total area is covered by riparian forests. The Uroczysko Warta is one of the most important groups of these habitats not only in Poland, but also on the European scale. It was assumed that the implementation of simple land and water system restoration systems - gates, barrages, culverts with backwater valve gates - may promote recreation of advantageous hydrological relations. This study presents results of water monitoring in the Uroczysko Warta Wilderness and the volume of deadwood formed as a consequence of hydrometeorological conditions. The paper provides a detailed description of climate characteristics (air temperature and precipitation) in the 30-year period of 1988-2017, i.e. after the commissioning of the Jeziorsko reservoir along with the hydrological characteristic of the wilderness area in the years 2009-2017 (water stages in the Warta river and in the Lutynia river, water stages in oxbow lakes and groundwater tables) and the volume of deadwood formed in the years 2006-2014. Water stages in the Warta and the Lutynia as well as water levels in oxbow lakes and groundwater tables show considerable mutual correlations. This indicates efficient operation of constructed land reclamation systems. The volume of formed deadwood shows no evident trends, only a close relationship with climatic conditions. Thus it may be hypothesised that the concept for the protection of floodplain forests in the Uroczysko Warta, consisting in the buffer supply of oxbow lakes at high water stages in the Warta and the Lutynia is appropriate, particularly since waters supplying the wilderness area do not stagnate, but they move within the ground.