[Critical tidal level for planting Kandelia candel seedlings in Xiamen]

Plantable tidal flat is one of the most important factors affecting the survival rate of mangroves seedlings in forestation. In this paper, an experiment was conducted in the tidal zones of Umbrette Natural Reserve in the Dayu Island of Xiamen in May 2003 to investigate the critical tidal level for Kandelia candel forestation. The results showed that the tidal level of 0.99 m above the zero tidal level of the Huang Ocean was not suitable for planting K. candel seedlings, because the waterlogging time at this tidal level was longer than 8 h per-tide-cycle, and the survival rate was lower than 50% . At 1.62 m above the zero tidal level of Huang Ocean, K. candel seedlings had the best growth and the highest photosynthetic assimilation, with a survival rate of 90%. At 1.31 m above the zero tidal level of Huang Ocean, K. candel seedlings could still grow well. It could be concluded that the tidal level of 1.62 m was optimal for planting K. candel seedlings, and the critical tidal level of K. candel seedlings in the coastal areas of Xiamen was not lower than 1.31 m above the zero tidal level of Huang Ocean, where the waterlogging time was not longer than 5.6 h per-tide-cycle.