Early growth of seven mangrove species planted at different elevations in a Thai estuary

Abstract

This study aimed to determine the effect of elevation on survival and growth of mangrove seedlings during the establishment period. Seven typical mangrove species, Rhizophora mucronata Poir, R. apiculata Bl., Bruguiera cylindrica (L.) Bl., Ceriops tagal (Pirr.) C.B. Rob., Sonneratia alba J. Sm., Avicennia officinalis L. and Xylocarpus granatum Koenig were planted at various topographic sites in an intertidal zone of Phang Nga province, southern Thailand. These six bare areas included two that were abandoned after tin mining and four gap areas in natural habitats in June 1998. The experimental plots were on a slope and showed a maximal elevation difference of 1.8 m. The plots were naturally submerged with 2–3% saline water twice a day. Salinity, pH and the concentrations of several ions in the soil water were similar in all the plots. Survival and growth performance of seedlings were measured every 6 months. Many seedlings of B. cylindrica, C. tagal and X. granatum planted at lower elevations died with a year. R. mucronata and S. alba survived even at the lowest elevations, but showed changes in growth rate in response to topography. Thus, early growth of the seven mangrove species at different elevations differed and showed increasing tolerance to higher tidal inundations in the order: R. mucronata, S. alba, R. apiculata, A. officinalis, C. tagal, B. cylindrica and X. granatum. These findings provide guideline information for appropriate species selection in a mangrove rehabilitation program.