SOIL-SALINITY AND PH IN JAPANESE MANGROVE FORESTS AND GROWTH OF CULTIVATED MANGROVE PLANTS IN DIFFERENT SOIL-CONDITIONS

Soil conditions of mangrove forests in southern Japan were found to correlate largely with zonal distributions of the species. Kandelia candel grew in soils with low salinity and low pH, Avicennia marina, Rhizophora stylosa and Sonneratia alba in soils with high salinity and high pH, and Bruguiera gymnorrhiza in soil with a wide range of pH but limited range of salinity. Lumnitzera racemosa colonized soil with a wide range of pH and medium salinity. Seedlings of Kandelia candel, Bruguiera gymnorrhiza and Rhizophora stylosa were planted in soils with differing salinity and pH. Optimum seedling growth of Kandelia, Bruguiera and Rhizophora occurred when plants were cultivated in soils similar to those of their natural habitats, suggesting that growth of mangrove species and their zonal distributions were regulated by salinity and soil pH.