Abstract
Mangrove is a vegetation distributed in seashore lines and estuaries in tropical and sub-tropical zones. The distribution patterns of mangrove species are influenced by some environmental factors, such as submergence time, salinity, character of soil substructure, etc. Especially, salinity is one of the main factors to determine the mangrove distribution and a change of mangrove species caused by salinity can be observed along tidal river. This study was conducted to understand relationships between distribution of mangrove species and salinity level along the tidal river. Three tidal rivers shorter than 50km were selected for the survey, which are the Linao and the Cabuyo Rivers in Cagayan Province, and the Kabibihan River in Quezon Province in the Philippines. As salinity of river water diminishes, composition of mangrove species is also changed. Only Nypa fruticans revealed wide suitability for salinity (0-29mgL^<-1>) among 28 species, while almost other mangrove species indicated partially high or low salinity. Tolerance of or adaptation to salinity appeared to lie in a series as Major components>Minor components>Associates. However, most mangrove species has wider adaptation to salinity and no apparent relationship is observed between dominance and salinity. Therefore, it is difficult to explain mangrove distribution pattern such as mangrove zonation only salinity factor.
