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Landscapes and Ecosystems of Tropical Limestone: Case Study of the Cat Ba Islands, Vietnam

Author(s): Quan Nguyen Van | Thanh Tran Duc | Huy Dinh Van

Journal: Journal of Ecology and Field Biology
ISSN 1975-020X

Volume: 33;
Issue: 1;
Start page: 23;
Date: 2010;
Original page

Keywords: Cat Ba Islands | geography | hydrography | human activities | topography

The Cat Ba Islands in Hai Phong City, northern Vietnam, consist of a large limestone island with a maximumheight of 322 m above sea level and 366 small limestone islets with a total area of about 180 km2. The islands are relictsof karst limestone mountains that became submerged during the Holocene transgression 7000 – 8000 year ago. Thecombination of the longtime karst process and recent marine processes in the monsoonal tropical zone has created avery diversity landscape on the Cat Ba Islands that can be divided into 3 habitat types with 16 forms. The first habitat typeis the karst mountains and hills, including karst mountains and hills, karst valleys and dolines, karst lakes, karst caves, andold marine terraces. The second habitat type is the limestone island coast, including beaches, mangrove marshes, tidalflats, rocky coasts, marine notch caves, marine karst lakes, and bights. The third habitat type is karst plains submerged bythe sea, including karst cones (fengcong) and towers (fengling), bedrock exposed on the seabed, sandy mud seabed, andsubmerged channels. Like the landscape, the biodiversity is also high in ecosystems composed of scrub cover – bare hills,rainy tropical forests, paddy fields and gardens, swamps, caves, beaches, mangrove forests, tidal flats, rocky coasts, marinekrast lakes, coral reefs, hard bottoms, seagrass beds and soft bottoms. The ecosystems on the Cat Ba Islands that supportvery high species biodiversity include tropical evergreen rainforests, soft bottoms; coral reefs, mangrove forests, andmarine karst lakes. A total of 2,380 species have been recorded in the Cat Ba Islands, included 741 species of terrestrialplants; 282 species of terrestrial animals; 30 species of mangrove plants; 287 species of phytoplankton; 79 species ofseaweed; 79 species of zooplankton; 196 species of marine fishes; 154 species of corals; and 538 species of zoobenthos.Many of these species are listed in the Red Book of Vietnam as endangered species, included the white-headed or CatBa langur (Trachypithecus poliocephalus), a famous endemic species. Human activities have resulted in significantlychanges to the landscape end ecosytems of the Cat Ba islands; however, many natural aspects of the islandsd have beenpreserved. For this reason, the Cat Ba Islands were recognized as a Biological Reserved Area by UNESCO in 2004.

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