Wednesday, February 25, 2009
History and Biodiversity of Singapore’s mangroves
At the time of the founding of modern Singapore in 1819, forest covered practically the whole of the main island. Of the original forest area, evergreen rain forest made up 82%, mangrove 13% and freshwater swamp forest, 5%. Today, only about 28.6 sq km of land area is still covered by primary and secondary forest, and this habitat loss in Singapore has reduced her primary forest cover to an estimated 0.2% of the land.
Singapore is a city state off the southern tip of Peninsular Malaysia, with 64 islands, including the main island of Singapore which is approximately 42 by 23 km. The republic has an area of 647.5 sq km, and a population of some three million people consisting of ethnic Chinese, Malays, Indians, Eurasians and other ethnic groups. Being only approximately 137 km north of the Equator, Singapore has a tropical climate with relatively uniform temperature, abundant rainfall and high humidity throughout the year. The average daily temperature is 26.7 degC (range 23.9-30.8 degC). Average annual rainfall is 2,353 mm with no distinctly dry or wet periods. The daily relative humidity averages at 84.3%.
With industrialisation and development, Singapore's area is now as follows: built-up (49.7%), with the remainder as farms (1.7%), forest (4.4%), marsh and tidal waste (2.4%) and others (including inland reservoirs, cemeteries, public gardens, etc.) (41.9%). With a population density of 5,354 per sq km, the third highest in the world, the pressure for land is thus very high.Estuarine and tidal habitats have been badly affected by the construction of reservoirs and land reclamation. Six estuarine reservoirs were formed by damming rivers draining to the north and west coasts between 1972 and 1984. From the 1960's to the present day, land reclamation has increased the original land area by one-tenth, altering most of the southern and north-eastern coasts.
Mangrove forest cover has been reduced from an estimated 13% in the 1820's to only 0.5% of the total land area. Mangrove forest.is now found only in small patches with the largest areas in the northern part of the main island and on Pulau Tekong, Pulau Ubin and Pulau Semakau. In the 90's, large mangrove areas west of the Causeway were developed for housing and other uses.
Some of the more interesting mangrove locations: here are some sketch maps with site codes that can be used as a reference.
Mandai Besar/KechilLim Chu KangKranjiSungei PandanSungei Punggol andPulau Tekong and Pulau UbinThe mangrove forests that remain are no longer complete ecosystems. As with habitats all over Singapore, animals at the top of the food chain have long since disappeared. In mangroves, this means the absence of tigers and crocodiles. However, this also means that it is relatively safe for researchers to explore without fear of disappearing!
Botanists of the National Parks Board discovered this previously undocumented stand of Sonneratia caseolaris trees at Sungei Seletar in 1998. It is actually viewable in the distance from Lentor Avenue! This tree is thought to be associated with fireflies, and can tolerate freshwater conditions. In the foreground is the characteristic fruit.
And researchers have been busy! Even with seed plants quite well accounted for, new records or rediscoveries are revealed. Botanists discovered a stand of Berembang (Sonneratia caseolaris) in the upper reaches of Sungei Seletar only last year (1998). Prior to this, only a single tree of this species in Woodlands was known of in Singapore!The checklist of the more diverse fauna is far from complete.Quite incredibly, even in just the small north-western portion of the very little mangrove that we have left, collections by local and international scientists in the 1990's alone have led to the description of many new species of animals!
There are lots more new species out there, with many interesting stories about their lives. The little mangrove we have left is still a very interesting place, and promises to reveal more in the years to come.
Mangrove Swamps consist of a variety of salt-tolerant trees and shrubs that thrive in shallow and muddy saltwater or brackish waters. Mangroves can easily be identified by their root system. These roots have been specially adapted to their conditions by extending above the water. Vertical branches, pheumatophores, act as aerating organs filtering the salt out and allowing the leaves to receive fresh water.
Mangroves are thought to have originated in the Far East then over millions of years the plants and seeds floated west across the ocean to the Galapagos Islands. Mangroves live within specific zones in their ecosystem. Depending on the species they occur along the shoreline, in sheltered bays, and others are found further inland in estuaries. Mangroves also vary in height depending on species and environment.
living nature
4:54 PM
