|Basic Concepts in Environment, Agriculture and Natural Resources Management: An Information Kit (IIRR, 1993, 151 p.)|
|Freshwater and marine ecosystems|
The mangrove ecosystem is commonly understood to be made up of a collection of woody plant species associated with characteristic fauna and flora and anaerobic soils found in the intertidal zone. They are often referred to as coastal woodland, tidal forest and mangrove forest.
Ecological and economic importance
· Provide food and shelter for a large and varied group of fishes and shellfish. The leaf detritus (fallen and decaying leaves) provides the base of the major mangrove community food chain. The aerial roots provide shelter for many species of commercial fish and shellfish, particularly in their juvenile and most predator prone stages.
· Provide protection from storm surges and high winds associated with tropical typhoons. This is important in a country that is hit by an average of 20 typhoons a year.
· Serve as protection against soil erosion. Soil erosion and sedimentation causes in the ocean is the number one cause of coral reef degradation.
· Serve as land builder through soil accretion. Sediment from the land collects among the dense roots building up the land.
· Trap coastal pollutants which may otherwise severely damage adjacent marine ecosystems.
Serve as wildlife sanctuary.
· Offer aesthetic, educational and scientific values.
· If used on a sustained yield basis (proper harvesting), can provide timber, firewood, charcoal, pulp and paper, extractives, nipa sap, nipa shingles, cellulose xanthate, oil, medicine, resin, tea and livestock supplements.
· Present status of Philippine mangroves
· In 1918, there were 450,000 ha estimated of mangrove areas in the Philippines. Since then, there has been a decreasing trend from 375,020 ha in 1950 (NAMRIA) to only 139,100 ha as of 1988 NFRI). The rate of deforestation averages more than 4,000 ha/year. The decrease in mangrove cover over the years can be attributed to harvesting of mangroves for charcoalor fuelwood production and by forest clearing for fishpond development. As of 1989, a total of 210,681 ha of mangrove forests have been converted to fishponds (BFAR).
Decreasing trend in mangrove cover in the Philippines
Causes of mangrove destruction
· Overexploitation by traditional users.
· Destructive action resulting from activities generally unrelated use of mangroves:
· Commercial timber harvesting
· Conversion of mangrove areas for aquaculture (e.g., fish, shrimp, prawns), agriculture, saltponds and urban development
· Mining/mineral extraction.
How mangroves propagate