Hydrologic Characteristics as a Controlling Factor on Vegetation Structure and Biological Integrity in Lentic Ecosystem

초록

Many reservoirs were created in stream valleys by the construction of a dam for the purpose of water supply, hydroelectricity, flood control, canals, flow balancing, and recreation. The diverse flora and vegetation can be established on the drawdown and littoral zones around margins of the reservoirs. The four key factors such as water level control, shoreline topography, substrate conditions and vegetation establishment should be considered in the conservation and management of biodiversity on the shoreline zone of reservoirs. The flora, the structure and distribution of vegetations, and the hydrologic and topographic environments were investigated in the shoreline of various reservoir ecosystems to study on relationships between the environmental factors and vegetation characteristics. The patterns of water level fluctuation characteristic are variable in the purpose of reservoir. The vegetations of reservoir are different by the water level fluctuation. We classified the vegetation characteristic of the reservoirs into three ranges according to the water level fluctuation. The water level fluctuation of the flood control reservoirs such as Reservoir Soyang and Paro is high and gentle. This type of reservoir annual water level fluctuation is very wide about 20 m. The water supply reservoirs have unstable aspects of water level fluctuation which annual change is about 10 m. Typical water supply reservoirs are agricultural Reservoir Wangsong and Bulgap. The reservoirs for hydroelectricity show stable water level fluctuation less than 2 m. Reservoirs Paldang and Chuncheon are in this type of reservoir. In flood control reservoir, the number of flora and aquatic plant was low and there was no submerged macrophyte. But hygrophytes, such as Bidens frondosa, Persicaria species and Calystegia japonica, are dominant. In this type of reservoir, only few macrophytes existed because of problem of water supply. There were lots of plant species in the water supply reservoirs r