Abstract
Lake Izunuma is a shallow eutrophic lake located in the northern part of Miyagi Prefecture, Japan. Lotus (Nelumbo nucifera) is the dominant species of the lacustrine vegetation, which has possibilities of accelerating the eutrophication through long-term accumulation of the dead body. In this study, field observations were conducted to understand annual cycle of nutrients (nitrogen, phosphorus, carbon) with regard to growth and mortality of lotus community. Nutrient stock was calculated from the results of the dry weight and nutrient content rate of lotus. Nutrients are stored mainly in living lotus shoots (leaves and stems) during the growing season, while they were transfered to dead body accumulated on the bottom after late autumn. Moreover, living lotus of approximately 388.5 g m-2 is supplied as dead body, and dead body of approximately 32.3 g m-2 accumulates without being decomposed in one year. From this result, possibility of organic matter storage in Lake Izunuma was suggested.
