Abstract:

The distributions of K、Na、Ca、Mg and Cl in different organs of Kandelia candel, Aegiceras corniculatum and Avicennia marina from Jiulongjiang estuary of Fujian, Bruguiera sexangula from Dongzhai harbor of Hainan and Rhizophora stylosa from Yingluo bay of Guangxi were studied. A comparison was made between these five mangroves and terrestrial tree: Castanopsis eyrei from Wuyi mountains of Fujian. The results indicated: (1)A efficient element redistribution mechanism existed in the 5 mangroves. There were larger differences in element contents between different organs of mangroves, while sodium distributed equally in the different organs of C. eyrei. (2)The osmoregulation of 5 mangroves was mainly fulfilled by salt accumulation.(3)Salt exclusion by roots was the most important salt tolerant mechanism of all mangroves. Keeping lower salt contents in above ground organs was the common feature of all mangroves. (4)Except the efficiency in salt exclusion by roots, no apparent deficiencies in element accumulation and distribution could be found between salt excluders (K. candel, B. sexangula and R. stylosa) and salt secreters (Avicennia marina and Aegiceras corniculatum).

Key words: Mangroves, Element distribution, Salt tolerance