Abstract
Three research points were set in a mangrove forest at Phang Nga area of Southern Thailand. Under-ground water samples were collected in rainy and dry seasons and were analyzed for composition of ions ; the relationshipbetween ion components of under-ground water and mangrove plants (species) was examined.
The main ion components of each research point were Na+ ion and Cl-ion in both dry and rainy seasons ; secondary ion components were Mg2+ ion, Ca2+ ion, and SO42- ion. Na+ ion and Cl- ion of research point B, i.e., that nearest to the open sea area in this research, showed higher amounts than those of the other two research points, A and C.
Mangrove plant species of each survey point 1 of the 3 research areas were Avicennia sp. and Sonneratia sp. of high tolerance to NaCl. On the other hand, mangrove species of the inner survey areas of the mangrove forest were observed species of low tolerance to NaCl. NaCl concentration of under-ground water, the inflow of seawater to the mangrove forest, and the outflow of seawater and river water to the sea were considered to be important factors in the distribution of mangrove plants. Especially, Na+ ion and ion concentrations are important factors for the growth of each mangrove species in the mangrove forest. SO42- ion concentration of all research points was higher than the average SO42- ion concentration of sea water.
