Before 1975, the world's largest mangal resources were found in Indonesia. In Kalimantan alone, nearly half of 1.8 million hectares of mangal were cleared between 1975 and 1994. In Sulawesi, 110,000 hectares in 1965 were reduced to 30,000 hectares by 1994. In the Phillipines, mangal areas were reduced from 400,000 hectares in 1920 to 140,000 hectares by 1994. And finally, from 1950 to 1983, 400,000 hectares of mangroves on the Vietnamese coast was reduced to 250,000. Features of increasing pressure on mangrove coasts Increasing human population in the coastal zone Loss of mangrove forest Increased coastal erosion Increased impact from storms Reduction in biodiversity Decreased fisheries production Decreased aquaculture pond production (in the long term) Potentially non sustainable exploitation of Mangroves Wood and other direct uses - Aquaculture and agriculture
Salt ponds - Palm and sugar cane plantations
Mining - Industrial and urban development - pollution
Water abstraction - Pollution
Mangrove forests can be heavily exploited as a source of wood and for other uses (e.g. industrial clearance of mangrove for wood chips to supply the rayon industry)
If tree cutting is not properly managed, the typical results are reduction in tree size and species diversity. Primary forest, dominated by large trees of 3-4 species of Rhizophora, Brugeria, Kandelia and Avicennia can be reduced to secondary forest of trees less than 5m high or even to mangrove scrub of 1 or 2 species, and only 1-2m high. In extreme cases, mangroves are completely cleared, leaving easily eroded mud flats.
Potentially sustainable (renewable) uses of mangroves
Fisheries - Small-scale fishing/collecting of crabs, shrimps, fish and molluscs. Nursery for commercial fish and shellfish.
Aquaculture - Integrated shrimp-cum-mangrove culture systems, crab culture, stock enhancement.
Wood - Firewood, charcoal, paper products, construction timber, wood chips, furniture.
Textiles - Synthetic fibres, dyes, tannins for leather
Fishing - Fish poisons, tannins for net preservation, poles for traps
Drugs - Pharmaceuticals
Food - Sugar, cooking oil, vinegar, honey, animal fodder.
Alcohol - Industrial alcohol fermented from sugar
Coastal management - Shoreline and riverbank protection
Recreation - Eco-tourism
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