Differences in vegetation distribution in the drawdown zone of reservoirs according to their operation purpose

초록

Most of reservoirs in Korea were built by dam or levee constructions. The reservoirs show artificial fresh water ecosystem. In this study, the relationship between environmental factors and vegetation structures was evaluated in the water fluctuation zones in the Korean reservoirs. The relationship among environmental factors was analyzed using geomorphology, hydrology, water quality and soil environmental factors. The water level fluctuation range of Korean reservoirs is from 1 meter to 27 meter, The water quality of reservoirs was mesotrophy or eutrophy, and the sand content was high in soil environments of shoreline. Range, frequency and period of water fluctuation were distinctive from the usage of reservoirs. Flood control reservoirs had wide fluctuation range with low frequency and waterpower generation reservoirs had narrow fluctuation range with high frequency. The result of PCA (principal component analysis) showed that the type of reservoirs was classified by reservoir size, water level fluctuation, water quality, soil characteristics and organic matter. In the drawdown zones of 50 reservoirs, total 84 family, 236 genus and 375 species of vascular plants were found and it was classified 46 hydrophytes, 101 hygrophytes and 228 mesophytes based on life form. As a results of vegetation structure analysis using CCA (canonical correspondence analysis), reservoirs were classified into four types. Emergent hydrophytes was dominant in the waterpower generation reservoir group, floating-leaved hydrophyte was dominant in the agricultural water supply group. In the flood control reservoir group, annuals and biennials were dominant. Salicaceae was overlap among all types. The environmental factors what influenced to vegetation distribution were selected by CART (classification and regression tree) analysis. As a result of analysis, floating-leaved hydrophyte was influenced by water depth and LQI, emergent hydrophyte was influenced by water fluctuation range an