Abstract: The present paper deals mainly with the absorption, distribution and biological cycle of Ct and Na in 64-year-old Rhizophora stylosa mangrove community in Yinluo Bay of Guangxi, China. The results showed that: (1) In standing crop of the community, the pool amounts of Cl and Na were 349.39g.m-2 and 279.85g.m-2 (g. C1/g. Na=1.25, mol.C1/mol.Na=0.81) respectively; in which the aerial part and underground part held 211.00g. Cl.m , 159.16 g. Na.m-2 and 138.39g. Cl.m-2, 120.69g. Na.m-2 respectively. (2) The biological cycle of Cl and Na in the community were: annual uptake 41.18g. Cl.m-2, 26.56g. Na. m-2; annual retention ll.40g. Cl.m-2; 9.15g. Na. m-2; annual retention 28.78g. Cl. m-2, 17.41g Na.m-2; and cycle coefficient CI: 0.72, Na: 0.66. (3) The turnover period of Cl(12 yrs.) was faster than that of Na(16 yrs.). The enrichment ratio of Cl and Na for the community were 2.18 and 1.80 respectively.

Key words: Mangrove, Rhizophora stylosa, Cl and Na dynamic