The aboveground production, nutrient distribution and nutrient cyclings were compared between two Phargmites communis communities growing in the different salt contents of soil in a coastal salt marsh.
Inorganic nutrient contents of soil for plant growth were greater at the low salt stand than at the high salt stand except for sodium(Na). Maximum aboveground biomass of the plant at the low and the high salt stands were 2,533 and 1,719g dw/㎡, respectively, in August. Seasonal changes of nutrient content of biomass in dry weight decreased with growth except for Na. Nutrient contents in biomass per unit land area increased continuously as biomass increases, although the amonut of potassium(K) reached the maximum content in July and therafter decreased. Vertical distributions of total nitrogen(T-N) and phosphorus(P) increased with plant height, but Na showed the reverse trend. That of K was similar to the patterns for T-N and P in the leaves, and to the pattern of Na in the stems. The Na was greatly accumlated in underground biomass but transported scarcely to aboveground. Ath the low and the high salt stands, the ratios of the inorganic nutrients contained in the plant were 100 : 66 for T-N, 100 : 61 P, 100 : 62 for K and 100 : 97 for Na. The ratios of the amounts of nutrients retrieved to soil were 100 : 242 for T-N, 100 : 408 for P, 100 : 128 for K and 100 : 269 for Na, respectively. Turnover times of he T-N, P, K and Na in the communities were 56, 1, 15 and 174 years at the low salt stand, and 75, 2, 24 and 232 years at the high salt stand, respectively. In nutrient cyclings, all of the nutrients retrieving to soil were less than uptake by plant. Amo ng the nutrient, especially P is expected to be exhausted from soil, sooner or later, because of the harvest by men.
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