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Wetlands - Korea's most-threatened habitat: 2

Moving southward, extensive tidal-flats at Asan and Namyang, in southern Gyeongii Bay, and in Cheonsu Bay have already been largely reclaimed (the latter creating the Seosan reclamation lakes), while massively wide and complex flats still remain at the mouths of the Geum, Mangyeung and Dongjin Rivers.

The c. 15,000 ha of tidal-flat at the mouth of the Geum, presently supporting about half of the estimated minimum population of the rather distinctive osculans Oystercatcher (with a peak count of 5,700 in January 2001), are still threatened by a proposed reclamation plan. Worse still, the 25 km wide tidal-flats formed by the other two rivers are already part of the worlds largest ongoing coastal reclamation project: Saemankeum.

Recent data (e.g. Barter 2002) suggests the Saemankeum system is the single most important known shorebird site in the whole Yellow Sea, supporting over 100,000 shorebirds at peak times and many more through the year, including e.g. 50,000 Great Knots Calidris tenuirostris, c. 210 Spoon-billed Sandpipers Calidris pygmea and 61 Nordmann's Greenshanks Tringa guttifer. In total, probably 25 to 30 species of waterbird are found here in internationally important concentrations, including Black-faced Spoonbill and Chinese Egret on southward migration, and Saunders's Gulls in winter (with a peak of over 600). The 33 km long outer seawall will, if the project is not cancelled, be completed in 2006.

The south coast has a rather more complex topography, consisting of a series of deeper bays fringed by tidal-flats (used by small but significant numbers of Nordmann's Greenshanks on southward migration), as well as extensive areas of mud-rock mix and oyster beds, favouring staging Grey-tailed Tattler Heteroscelus brevipes and wintering Greater Scaup Aythya marila. There are also two major estuaries, those of the Soemjin River that flows into Gwangyang Bay, and the Nakdong: although remaining habitat at the Nakdong is much more diverse and birds rather more numerous (with peaks of 2,000 Whooper Swans Cygnus cygnus and several thousand Eastern Taiga Bean Geese Anser fabalis middendoffi), the industrial Gwangyang Bay now supports between 100 and 200 Black Brant Branta bernicla nigricans, the nations largest remaining flock. In addition, the south coasts milder temperatures allow large numbers of Common Shelduck Tadorna tadorna and Saunders's Gull to winter on a number of the remaining tidal-flats: Suncheon Bay alone supports over 15,000 Common Shelduck and 700-1,000 Saunders's Gulls.

Freshwater Wetland
Freshwater wetlands are largely concentrated in the historical floodplains of South Koreas major rivers: the Han in the northwest, the Geum, the Yeongsan, and the Nakdong. Many such areas have been extended in recent years through extensive reclamation of the coastal and intertidal zones, and converted for agriculture and other land uses. Although they support significantly over one million waterbirds in winter (largely on their one million hectares of rice-fields and associated reclamation lakes), they also support the vast majority of South Koreas 47.9 million human population, who live at some of the highest densities found anywhere in the world. As a consequence, few natural or even semi-natural freshwater wetland areas remain outside of the 4-kilometre wide DMZ separating the South from the North, and many sites are threatened by continuing degradation and inappropriate management techniques.

Freshwater wetlands can be subdivided into riverine wetlands (typically only semi-natural); remnant areas of natural floodplain wetland (probably totaling less than 10,000 ha nationwide); reclamation lakes; and rice-field (largely flooded between May and July, harvested in September or October, and left dry and bare through the winter).

Although rivers are largely only semi-natural (most are bunded and very disturbed, and support many human activities including extensive water extraction) several support waterbirds in internationally important concentrations (defined in accordance with the Ramsar Convention [Iran, 1971] as being either 1% or more of a known population of a species, or 20,000 or more individuals, supported regularly at a site), and several species of Special Conservation Concern. Probably 30-50 Scaly-sided Mergansers Mergus squamatus winter most years on rivers, along with significant populations of Mandarin Duck Aix galericulata (5,000-10,000 are resident nationwide, with up to 5,000 concentrated on Jeju Island in the far southwest in mid-winter). Long-billed Plover Charadrius placidus too are reasonably widespread, though the Crested Kingfisher Megaceryle lugubris, which is a widespread breeding species across China into Japan, has already effectively become extinct.

The few remaining near-natural areas of floodplain wetland, mostly concentrated in the DMZ and in pockets along the Nakdong River, have become increasingly important for a wide variety of species, but most especially cranes. Over 300 each of Red-crowned and White-naped Cranes winter at Cheolwon in the DMZ, and several thousand Hooded and White-naped Cranes stage on their migration, first in the DMZ and then at Gumi, on the Nakdong, on their way to and from Izumi in Kagoshima Prefecture, Japan. The Nakdong also has Koreas only waterbird-important Ramsar site, the 800 ha Woopo wetland, one of 34 sites supporting significant numbers of the declining Eastern Taiga Bean Goose. Not surprisingly, several floodplain dependent species have shown obvious declines, with the Crested Ibis Nipponia nippon extinct, and the Oriental Stork Ciconia boyciana last breeding in 1980, and now best regarded as a very scarce winter visitor (with 2025 nationwide most winters).