Natural colonization of native mangroves into exotic mangrove plantations in Leizhou Bay, South China

By comparing soil physical-chemical properties, community structure and recruitment of barren mangrove areas, native mangrove species plantations, exotic mangrove species- Sonneratia apetala Buch.Ham between plantations and natural forest, this paper examines the natural colonization of native mangrove species into rehabilitated exotic mangrove stands in Leizhou Bay, South China. We found that severely degraded mangrove stands cannot regenerate naturally without human intervention due to severely altered local environments, whereas some native species have recruited into the 4-10yr S. apetala plantations. In the first 10 years, the exotic species S. apetala perform (e.g., growth) better than native species such as Rhizophora stylosa Griff and Kandelia candel (Linn.) Druce. Statistic regression analysis shows that the S. apetala plantations could restore the organic matter condition in about 14 years. The investigation result shows even in 10 years old communities, the regeneration competition of S. apetala seems strong compare with native species. It is possible that we can use S. apetala plantation as pioneer species to improve degraded habitats so that native mangrove species can re-colonize quickly, but artificial reconstruction will be needed to move it out and get rid of its invasion after the deposition were improved to suitable for native species, so that the following rehabilitation could be done by natural processes of self-design. However, to make sustainable use of mangrove of South China, the priority must be to protect all the existing wetlands of mangrove in situ and put forward the long-term scientific program of rehabilitating.