Philippine mangroves: status, threats, and sustainable development.

The status of the Philippine mangroves is examined, the functions of mangrove areas are highlighted, the threats to mangrove resources are identified, and the prospects for sustainable use are discussed. The Philippines harbour 39 species of true mangroves belonging to the following genera: Acanthus, Camptostemon, Lumnitzera, Excoecaria, Pemphis, Xylocarpus, Aegiceras, Osbornia, Nypa, Aegialitis, Bruguiera, Ceriops, Kandelia, Rhizophora, Scyphiphora, and Sonneratia. The fauna is equally diverse. Apart from fish and shrimp, other animals collected from mangroves are crabs and lobsters, bivalve and gastropod molluscs, and other invertebrates. Mangrove services include coastal protection, erosion control, sediment stabilization, flood regulation, nutrient supply and regeneration, waste treatment, and wildlife habitats. Mangroves could be valuated at around 10,000 US$/ha/year. As elsewhere, it can be expected that the net present value is highest if the mangrove cover is maintained. The decline of mangroves from about 500,000 ha in 1918 to only 120,500 ha in 1994 was caused by overexploitation by coastal dwellers and to conversion to settlements, agriculture, aquaculture, salt pans, and industry. The remaining mangroves should be conserved. It is recommended to establish the following zones: (1) protected forest; (2) productive forest; (3) reforestation areas; and (4) conversion areas.