ASSESSMENT OF CONSEQUENCES OF THE RUNOFF REGIME CHANGE FOR FLOODPLAIN ECOSYSTEMS WHEN CONSTRUCTING SMALL HYDRAULIC STRUCTURES ON LOWLAND RIVERS

Zh. V. Kuz'mina

Complex ecological investigations are carried out in broad-leaved forests in the reserves and national parks situated on the banks of the rivers Elbe, Danube (Germany), and Seim (central Russia). The state of terrestrial ecosystems along regulated and unregulated river reaches is compared. A significant negative effect of low-pressure hydraulic structures and small reservoirs on the vegetation and soils of floodplains, which shows up several decades later, is found. Based on the analysis of long-term trends in the annual mean water levels and discharges and annual precipitation in the river basins under study, a significant effect of the natural long-term variability of river runoff on the dynamics of the vegetation in floodplains is estimated.