State of the Art Information on Mangrove Ecosystems in Indonesia

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  1. Status and Trends of Mangroves in Indonesia
    1. GENERAL CONDITION OF MANGROVES IN INDONESIA

Indonesia is a tropical archipelago with coastlines measuring a total length of 95,181 km, making it the country with the fourth longest coastline in the world (EarthTrends WRI, 2003, and Rompas, RM.2009). All along the coast are the estuaries of rivers great and small that flow the whole year round thereby enabling mangroves to thrive, particularly on shores sheltered from the waves, such as lagoons, deltas, coral and sand bars. Currently, Indonesia’s mangroves cover 30,000 square kilometres, 21% of the global total mangrove area, and contain 45 (not including introduced species) of the world’s 75 species of true mangrove (Spalding et al., 2010). As a result, Indonesia is known as the country possessing the most mangroves, both in terms of area and number of species.

Mangroves play an important role in the lives of Indonesia’s coastal communities, because they provide habitat for fish, crustaceans and algae which form both food and a source of livelihoods. This is evident from the size of shrimp exports, which reach 1 billion dollars a year (KKP, 2009). Mangroves also fulfil other needs, such as timber for a variety of constructions, energy, dyes and medicines; their fruits can even be used to make jam, syrup and crisps for consumption. Mangrove timbers are known for their strength, which makes them suitable for construction, such as ceriops which is used for railway sleepers and handles for construction tools (Giesen et al, 2006). Each year, around 50 thousand to 300 thousand cubic metres of mangrove logs are obtained from timber concession company activities in mangrove forests (BPS, 2009). This does not include the timber exploitation activities carried out by communities living in the vicinity of mangrove forests, for construction and charcoal production.

The enormous economic value of mangrove timber has led to massive exploitation, especially on the four largest islands: Sumatera, Java, Kalimantan and Sulawesi. Between 1980 and 2000, it is estimated that 1-1.7 million hectares of mangroves were lost. The wide diversity in the uses of mangrove makes it difficult to determine precisely which activities are the most dominant causes of mangrove destruction. Giesen (2006) estimated that 25% of mangrove loss was due to the clearing of mangroves for fish pond aquaculture (tambak), and 75% from a combination of: land conversion for agriculture, degradation resulting from overexploitation, and coastal erosion. Differing from Giesen, the Forestry Ministry’s Analysis (2005) found that up to 2003, around 750 thousand hectares of mangrove had been cleared for aquaculture, indicating that the major single cause of mangrove loss (~50%) was in fact the construction of aquaculture ponds.

Mangrove degradation has resulted not only from human exploitation but also from natural disasters like the earthquakes and tsunami in Aceh. Analysis of satellite imagery by the National Institute for Aeronautics LAPAN (2005, in Dephut 2005) estimates that around 32,000 ha of Aceh’s mangroves were devastated by the tsunami on 26 December 2004, which also destroyed parts of the mangrove ecosystems on small islands in the waters to the west of Sumatera, not just as a result of the force of the tsunami but also because the mangroves were uplifted to a height of several centimetres above sea-level and therefore dried out and died.

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