Location and General Description
The southern margin of the Korean Peninsula, below 35° 30’ N latitude, and Cheju Island, about 60 km further south, support warm-temperate to subtropical evergreen broadleaf forests, the distribution of which appears to be determined primarily by the magnitude of winter cold and to a lesser extent by the degree of warmth during the summer growing season (Yim, 1977).
The Korean Peninsula is part of the East Asian monsoonal region and receives abundant summer precipitation with warm, humid conditions. Annual precipitation exceeds 1,000 mm throughout most of the Korean Peninsula, about two-thirds of which falls between June and September. During winter, movement of air from the Asian continent brings cold temperatures and generally dry conditions. The southern coast and Cheju Island have warmer and milder weather than other parts of South Korea. Mean temperatures on Cheju range from 2.5° in January to 25°C in July, with an annual mean of about 14°C. Snowfall occurs along the southern coast, but usually does not accumulate. Precipitation totals tend to vary considerably from year to year, and droughts are not infrequent. Although the Korean Peninsula receives some typhoons it is less vulnerable than other parts of East Asia such as Japan, Taiwan, and the eastern coast of China.
The southern coast and islands are regions where plants typical of the warm-temperate zone grow in abundance. In valleys where formations of granite and granite-gneiss lie exposed, forests of Carpinus laxiflora are found. Characteristic tree species of this ecoregion include the laurel Persea thunbergii, large specimens of which, exposed to salty shoreline breezes, may acquire a twisted and gnarled physiognomy. Members of the oak family Quercus myrsinaefolia, Cyclobalanopsis acuta, and Castanopsis cuspidata also occur here, as do members of the tea family, such as Camellia japonica. Other locally abundant or ecologically significant tree and shrub genera include Elaeocarpus, Neolitsea, Daphniphyllum macropodum, Ilex integra, Hedera, Eurya japonica and Pittosporum tobira, Viburnam awabuki, and Cinnamomum camphora. Floristically, these forests show a clear similarity to the broadleaf evergreen forests that once extended in a broad belt across Asia from Japan and Taiwan to the Eastern Himalaya and the mountains of northern Indochina. Eleven of these fourteen genera are common to the subtropical forests of the Himalayan foothills in Nepal; two others occur at least as far west as Yunnan Province, China.
These forests have been greatly reduced in area by human activity. It is uncertain how far northward they might potentially extend on the Korean Peninsula, as this plains region has long been converted to agriculture. However a comparison to similar forests in Japan suggests that they once extended further north than they do at present. Today, the best remaining stands occur in protected areas (called Natural Monuments in Korea) such as Ulsan, Hampyeong, and Naejang-san.
Of 379 bird species recorded in South Korea, 111 are winter visitors and 90 are recorded as passage migrants that visit during the winter and spring. Most of these visit the southern region where conditions are most hospitable during the cold season. Birds include rare white-bellied black woodpecker (Dryocopus javensis), fairy pitta (Pitta nympha), and ring-necked pheasant (Phasianus colchicus torquatus).
Seventeen species of terrestrial mammals have been recorded on Cheju Island. Today, wild boar, deer, and wild cats that once occurred on the island are extinct. Today Cheju supports roe deer, weasels and various rodents that are commensal, or tolerant, of humans, including hamsters, field mice, house rats and two bat species. There are also 207 kinds of birds (species and subspecies) recorded on the island, and eight amphibian and reptile species. Ullungdo Island, located about 135 km (84mi) east of the Korean peninsula, is devoid of endemic mammals. The island's mammals are limited to six species (two bats, one shrew, and three house rats) that also occur on the mainland. There are no amphibians or reptiles native to the island, although some frogs and snakes have been introduced. To date, 54 species of birds have been recorded on the Ullungdo Island.
A subspecies of the critically endangered crested shelduck, called Kuroda's sheldrake Tadorna cristata kuroda, once occurred along the southern coast of Korea. Today, only three mounted specimens testify to the existence of this bird in Korea. The last time this species was seen in Korea was in December 1916, when a female bird was shot on the lower reaches of the Naktonggang River near Pusan. This subspecies is listed in the IUCN Red Data Book, but is believed to have become extinct. According to the World Conservation Monitoring Center, the most recent confirmed sightings of any member of this species included at least three individuals on islands southwest of Vladivostok, Russia in May and June 1964, six on the northeast coast of North Korea in March 1971, and two in eastern Russia in March 1985. Two endangered crane species occur on the Korean Peninsula. The very rare red-crowned crane (Grus japonensis) overwinters along rivers and in coastal and freshwater marshes and breeds in deep freshwater marshes. The white-napped crane Grus vipio winters here.
Neottopteris rigida is an orchid of Cheju Island, Crinum maritimum is an onion of Cheju Island. Fatsia japonica is a striking ivy shrub with broad, palmately divided leaves that occurs on islands of the south coast.
As in many parts of East Asia, low-lying plains have been converted to agriculture land. Thus, the remaining Central Korean Deciduous Forest is mostly confined to the mountains and hills that cover an extensive area of the Korean Peninsula. The southwestern part of the ecoregion supports very little of its potential vegetation.
Korea is a country successful in forestation and erosion control projects for rehabilitating degraded areas.
Types and Severity of Threats
Justification of Ecoregion Delineation
The ecoregion boundary is based on Yim's (1968; also Yim 1977) warm-temperate evergreen broadleaf forest (zone A) encompassing the southern coasts of the Korean peninsula and surrounding islands. Characteristic species include Machilus thunbergii, Cyclobalanopsis acuta, Castanopsis cuspidata ssp. sieboldii, Camellia japonica. The region shows a close resemblance to the warm-temperate lucidophyll forests of southwestern Japan (Yim, 1977).
Ching, Kim K. Temperate deciduous forests in East Asia, In D.W. Goodall, Editor in Chief, Ecosystems of the World, Volume 7.
Kong, Woo-Seok and David Watts. 1993. The plant geography of Korea with an emphasis on the alpine zones. Kluwer Academic Publishers. Dordrecht, The Netherlands.
Yim, K. B. 1968. Jorimhak Wonron (Principles of Silviculture). Hyangmunsa, Seoul. (in Korean)
Yim, Yang-Jai. 1977. Distribution of forest vegetation and climate in the Korean Peninsula. Japanese Journal of Ecology 27:269-278