Hydrologic conditions of ecological succession in Biebrza and Upper Narew valleys

摘要

The largely natural valleys of Biebrza and Upper Narew are characterized by a unique pattern of distribution of mires known as ecological succession. Results of several studies conducted in the valleys of the Biebrza and the Narew river have been used to examine relationships obtaining between mire type and distribution on the one hand, and hydrological conditions on the other. Special attention was paid to the manner of feeding and water levels in hydrogenic sites. In the Biebrza valley mire diversity and distribution in ecological succession is associated with changes in water levels in the river i.e., increase in the magnitude and energy of flow and greater amplitude of water level fluctuation. These changes entail intensification of the draining effect of the river on the valley modifying the development of its mires. In the Upper Narew valley mire diversity and distribution is likewise conditioned by the river, namely, its gradient: sites where the gradient is slight developed peatlands, those where the gradient is greater accumulate alluvial deposits. In the Narew valley there is no ecological succession typical for extensive basins of the Biebrza valley resulting from the draining impact of the Biebrza river on the level of groundwaters feeding the valley.