Stand structure, biomass, and net primary productivity of planted and natural mangrove forests in Batan Bay Estuary, Philippines

抄録

Monospecific Rhizophora spp. trees have been planted for several decades in the Philippines to offset heavy mangrove deforestation resulting mainly from aquaculture pond construction. The reforested mangrove studies are required for evaluating their ecological roles. We surveyed the forest structure, biomass, and net primary production (NPP) at an 18-year-old R. mucronata plantation site (PL) and a secondary natural mangrove site (NM) at Batan Bay Estuary, Philippines. The survey showed that PL had a>8,000 ha^－1 tree density, 351.6 Mg ha^－1 biomass, and 73.2 Mg ha^－1 year^－1 NPP, exceeding the values at NM (670 ha^－1 tree density, 130.7 Mg ha^－1 biomass, and 22.7 Mg ha^－1 year^－1 NPP). The low biomass quantity in NM was due to the residual effects of a typhoon in November 2013; however, the NPP showed a quick recovery which implies the disturbance-adapted characteristics of pioneer species such as Avicennia marina and Sonneratia alba. At PL, the biomass and NPP were large, though it has been known that monospecific Rhizophora spp. plantation has been vulnerable to the risk of stand destruction due to strong typhoons. We concluded that the A. marina and S. alba, which dominated as natural mangrove stand, are suitable for mangrove reforestation because it quick recovered even after the typhoon impacts.