Location and General Description
The Northeast China Plain consists of a low-lying alluvial basin that originates at the north end of the Bay of Bohai and extends northward, tracing the catchment of the Liao River. At the top of the Liao watershed, the lowlands extend across a low divide to follow the Songhua River toward its confluence with the Heilongjiang (Amur) River which flows through the Russian Far East to enter the Pacific at the Sea of Okhotsk. Natural vegetation of this plain is deciduous broadleaf forest dominated by oak or a mixture of hardwood species. Many areas are fairly dry. Others are prone to seasonal flooding, so forests here probably once included woodland, grassland and flooded grassland (swamp) components, with closed canopy forest restricted to the wetter, but well-drained sites. At approximately 47oN latitude, the deciduous broadleaf forest undergoes a transition to a more boreal mixed conifer-deciduous formation, marking the northern limit of this ecoregion. Today the forest has been extirpated, and the plain is farmed intensively.
In the southern lowlands, near the Bay of Bohai, vegetation is deciduous broadleaf forest comprised of oaks (Quercus liaotungensis, Q. mongolica). Nearby low hills support mixed hardwood stands of maple Acer spp., Tilia amurensis, elm (Ulmus propinqua), and ash (Fraxinus manshurica). Stands of Chinese red pine (Pinus tabulaeformis) also occur in some places on the plains, although the deciduous forest is more abundant. Today, the plain of the Liao River is intensively farmed, so few traces of the original forest remain. A semi-wild scrub does occur in some areas where the scrub oak, Quercus acutissima, is the dominant tree species.
Northward, the plains narrow between the Changbai Mountains to the east and grasslands to the west. Here, Mongolian oak (Quercus mongolica) remains as an important species with Daurian birch (Betula dahurica) and the shrubs bushclover (Lespedeza bicolor) and hazel (Corylus heterophylla). Deciduous forests continue to dominate the plains along the Songhua River here in the most northeastern corner of China. Drier sites, such as south-facing slopes and disturbed areas (of which there are many) tend to support an association of Q. mongolica and Betula dahurica, while Acer spp. and Betula spp. grow in moister locations. Scrublands and the understory of drier more open forest stands support thorny shrubs such as Daurian buckthorn (Rhamnus dahuricus), hawthorn (Crataegus pinnatifida) and Daurian rose (Rosa dahurica).
One area of high biodiversity found within this ecoregion is the mouth of the Liao River where extensive wetlands, reedbeds, sand, and mudflat areas remain. Here the Shuangtai Hekou Nature Reserve (800 km2) protects breeding habitat for endangered red-crowned cranes (Grus japonensis) and Saunders’ gulls (Larus saundersii). Intertidal mudflats are important to shorebirds on the Siberian-Australasian flyway.
Yiwulu Shan is a hilly area near the Northeast China Plain where a Nature Reserve (114 km2) protects some forest similar to the potential vegetation of the plain. Here, stands consist of a mixture of deciduous broadleaf species and Pinus tabulaeformis. Forests here probably represent the most intact stands in the western part of Laioning Province, and may be closest to a surviving example of the broadleaf forests that once covered the plains.
Deciduous forests of the Northeast China Plain have been largely replaced by agriculture. Today, remnant forest patches can be seen in places where they have been protected for religious reasons, or where the land is steep and inaccessible.
The Northeast China Plain has been targeted for afforestation by the Chinese Government. The Northeast Shelterbelt Project is intended to protect farmland by reducing wind deposition of sand from the loess hills to the west, and to help agricultural areas retain water. This is the eastern part of "a great green wall" planned to extend across northern China by 2050. Opportunities exist for planting this forest in a way that will promote restoration of native habitat, although this concept has yet to be adopted by project planners.
Types and Severity of Threats
Shuangtai Hekou Nature Reserve is surrounded by areas of high population density and threatened by development and coastal reclamation. Hunting, reed-cutting, water pollution and a nearby oil industry also threaten habitat within the reserve.
Justification of Ecoregion Delineation
Because of the fertile soils, most of the plain has been converted for agricultural use and few original deciduous broadleaf forests are left.. Therefore, the boundaries correspond to the CVMCC (1979) Vegetation Map of China agriculture classes for (70a, 71a,b). These vegetation classes are located within the Northeast China Plain biogeographic subunit (15f) in the Oriental deciduous forest region according to Mackinnon et al. (1996).
Chinese Vegetation Map Compilation Committee. 1979. Vegetation map of China. Map (1:10,000,000). Science Press, Beijing, China.
International Crane Foundation. Crane Species. Retrieved (2000) from: http://www.savingcranes.org/species/default.asp
Laidler L., and K. Laidler. 1996. China’s Threatened Wildlife. Blandford, London.
MacKinnon, J. 1996. Wild China. The MIT Press, Cambridge MA.
Mackinnon, J., M. Sha, C. Cheung, G. Carey, Z. Xiang, and D. Melville. 1996. A biodiversity review of China. World Wide Fund for Nature, Hong Kong.
Zhao, J., editor. Zheng Guangmei, Wang Huadong, Xu Jialin. 1990. The Natural History of China. McGraw Hill Publishing Company, New York.
Prepared by: Chris Carpenter
Reviewed by: In process