Distribution of Arboreal Arctic-Alpine Plants and Environments in NE Asia and Korea

Geographical Review of Japan Vol. 72 (Sec. B), No. 2, 122-134, 1999 Distribution of Arboreal Arctic-Alpine Plants and Environments in NE Asia and Korea Woo-seok KONG* and David WATTS** * Departmentof Geography, KyungHeeUniversity, Seoul, 130-701,Korea **Departmentof Geography, Hull University, Hull HU6 7RX,U. K. Abstract: The distribution of arboreal arctic-alpine plants in NE Asia and Korea is discussed, The presence of large numbers of species of the arctic-alpine flora in the Korean Peninsula, and especially the global southernmost distributional limits for certain species, may primarily be attributed to palaeo-environmental factors, since it cannot be wholly explained by reference to present environmental conditions. The disjunctive distribution of many arctic-alpine plants in NE Asia and the Korean Penin sula, as well as the Japanese Islands, suggests a former continuous distribution of these both regionally and on a broader scale. It also implies their range extension down-slopes and southwards during the Pleistocene glacial phases, and the subsequent breakdown of a former continuous range into fragments as the climate ameliorated during the post-glacial warming phase. The arctic-alpine flora, now mainly on the peaks of the Korean mountains, have been able to persist in alpine belts thanks to their harsh climatic conditions, sterile soil, rugged topography and cryoturbation. The horizontal and vertical distributional limits of some species seem to coincide with the maximum monthly summer isotherms, and the continued survival of alpine plants in Korea is in danger, if global warming associated with the greenhouse effect takes place. Key words: arctic-alpine plants, NE Asia, Korea, the global southernmost distributional limit, Pleistocene glacial phases, post-glacial warming phase seems little doubt that arctic-alpine species Introduction from farther north migrated south into Korea, and some at least stayed there, greatly adding The flora of East Asia is extremely rich and to the already rich temperate and sub-tropical distinctive, including more than 20endemic fl ora. During and since the Quaternary, con families and over 300endemic genera, and a spicuous local endemism has taken place, so huge number of endemic species (Takhtajan adding to the richness of this bio-diversity. In 1986). An intermediate region between temper excess of 4,500species of vascular plant species ate NE Asia and subarctic Siberia, which con are known to reside within the Korean Peninsu tains the Maritime Territory of Russia, NE la, a surprisingly rich assemblage, bearing in China, northern Korea, southern Sakhalin, and mind the fact that the area has been extensively Hokkaido of Japan, it is well characterised by a modified by man over the years. vegetation of mixed forests (Tatewaki 1963). It would be naive to expect a species to be However, no extensive research has been limited by a single climatic factor all round its carried out on the distribution of cold-tolerant range. Alpine and northern species, however, plants therein, including the arctic-alpine spe are known to be restricted in their distributions cies of NE Asia. to areas of low summer temperatures (Dahl The Korean Peninsula, a land of rich and 1951, 1998; Tralau 1961; Damman 1965, 1976; unique flora, largely escaped most of the Qua Korner 1999). From a historical viewpoint, the ternary glacial events, including extensive fossil record of arctic-montane plants has been snow cover. During the glacial maximum, there interpreted in the light of their present-day dis Distribution of Arboreal Arctic-Alpine Plants and Environments in NE Asia and Korea 123 tribution correlation with mean annual maxi Hulten (1958, 1962, 1971). They comprise first, mum temperatures of summer (Conolly 1970; more or less circumpolar plants with very dis Gauslaa 1985). Recently, the potential re rupted ranges (arctic and arctic-montane spe sponse of the vegetation to global climate cies); second, boreal plants with north-south change has also been investigated (Smith et al. races, or arctic-montane races overlapping the 1992; Hillier 1993; Krauchi 1992; Melillo et al. boreal area; thirdly, arctic-montane species 1996). If the widely predicted greenhouse effect occurring in the isolated southern mountains occurs, natural ecosystems will respond in but not occurring elsewhere south of the cen ways similar to responses in the past, but the tral Asiatic desert belt; and finally, plants effects on cold-tolerant arctic-alpine plants will known to have east-west races in their circum be more severe because of the rapid rates of polar range. temperature warming trends in Korea. More or less circumpolar plants with very This present work focuses on first, the com disrupted ranges (arctic and arctic-montane parative analysis of the current distributional species) include Diapensia lapponica and pattern of arboreal arctic-alpine plants in NE Phyllodoce caerulea. The circumpolar Diapensia Asia focusing on the Korean Peninsula; and lapponica is divided into two major races, subsp. second, the reconstruction of migration and lapponica and subsp. obovata. Diapensia lap survival of arctic-alpine plants mainly in Korea, ponica subsp. obovata shows an amphi-Pacific as well as the vegetational shifts along climatic range (Figure 1). On the Pacific side this species changes in the past, based upon palaeo is known to be present continuously from botanical data. North Korean flora data are Alaska, the Chukchii Peninsula, Arctic areas, collated from the work of Chung and Lee the Russian Far East, Kamchatka, the Kuriles, (1965). Sakhalin, Hokkaido, Honshu and Korea. This species prefers dry slopes and rocky cliffs in Arctic-Alpine Arboreal Plants of NE Asia alpine regions (Ohwi 1984). On the summit of Mt. Halla of Cheju Island, Diapensia lapponica The floristic richness of NE Asia, which is due subsp. obovata grows solely in Korea and this to its great diversity in topographic, climatic site is designated as the global southernmost and edaphic conditions, as well as the absence limit of this species. of extensive glaciation during the Pleistocene, The circumpolar Phyllodoce caerulea shows is a well-known fact (Li 1953). The major types both amphi-Atlantic and amphi-Pacific ranges of natural vegetation in temperate NE Asia (Figure 1). Phyllodoce caerulea grows well on include mixed northern hardwood forest, decid acid soil and reaches to about 1,850m a. s. l. in uous oak forest, birch forest and montane Scandinavia and to about 2,600m a. s. l. in the boreal coniferous forest (Wang 1957; Ohsawa Pyrenees, but is very rare in Scotland and in 1990, 1991, 1993a, b). Though the survival of the Pyrenees. On the Pacific side Phyllodoce arctic plants on the summits of the high moun caerulea occurs around the northwestern Pacific tains of Japan has been discussed (Takeda Ocean from Alaska, Siberia, the Chukchii Penin 1913; Okitsu 1993; Okitsu et al. 1984, 1989, sula, Russian Far East, Kamchatka, the Aleu 1995), very little biogeographical research has tian Islands, Sakhalin, Hokkaido, Honshu and dealt with a comparative analysis of northern Korea. The northern part of the Korean Penin or circumpolar floristic elements of NE Asia. sula is known as the global southernmost limit A knowledge of the floristic elements of a of this species. region is helpful in understanding the path Boreal plants with north-south races, or ways of migration into the region concerned arctic-montane races overlapping the boreal (Stace 1980). This present work is focused on area include Juniperus communis, Vaccinium the biogeography of the circumpolar flora in vitis-idaea, V. uliginosum, Ledum palustre and NE Asia. For the arboreal arctic-alpine plants Empetrum nigrum. Juniperus communis is the of NE Asia and the Korean Peninsula, four most widely distributed coniferous species and different distributional elements are noticed by has also been reported from Tertiary intergla 124 W. -s. Kong and D. Watts (Modified from Hulteu, 1962, 1971) Figure 1. Global distribution of arctic-alpine plants (Diapensia lapponica subsp, obovata, Phyllodoce caerulea and Vaccinium vitis-idaea subsp. minus). cial and late glacial layers. Though Juniperus species grows well in coniferous woods and on communis var. montana has been reported in the alpine slopes (Ohwi 1984). The scattered dis peaks of Korea (Hulten 1962), at present only junctive range occurred on the south of the Juniperus sibirica and J. chinensis var. sargentii circumpolar zone, and includes central China, grow. This species occurs also in Sakhalin, southern Japan and northern Korea. Hokkaido and Honshu of Japan. Vaccinium uliginosum is a circumpolar Vaccinium vitis-idaea consists of two closely Eurasiatic lowland plant, in Scandinavia, the related races, chiefly the lowland race subsp. European mountain and eastern Asia. The spe major and the arctic-montane race, subsp. cies is common in both Eurasia and North minus. Vaccinium vitis-idaea subsp. minus, America, including Kamchatka, the Aleutian which is a circumpolar and amphi-Pacific plant, Islands, Hokkaido, Honshu and Korea, The occurs in North America, Scandinavia, Alaska, southernmost limit of continuous range in NE arctic Siberia, Chukchii, the Russian Far East, Asia includes central Korea and Japan. Fossils Kamchatka, the Aleutian Islands, the Kuriles, of Vaccinium uliginosum have been found in Sakhalin, Hokkaido, Honshu, Shikoku, Kyushu, Pliocene layers in France, and in the Cambridge Mongolia, NE China, and Korea (Figure 1). This area, Mass., U. S. A. Distribution of Arboreal Arctic-Alpine Plants and Environments in NE Asia and Korea 125 Ledum palustre subsp. decumbens occurs in are designated as one of the global south arctic North America, Siberia, Eurasia and the ernmost limits of this species. In the Alps, Himalayas. This species reaches the mountains Oxycoccus palustris ascends to about 1,200m of Scandinavia and merges with subspecies and in N. Italy to about 1,900m. Isolated palustris in the north. Isolated disjunctive ranges of Oxycoccus palustris subsp. microcarpus ranges of this species can be noticed in Siberia, in NE Asia are noticed from Japan and northern Kamchatka, Sikhote-Alin, the Kuriles, the Korea.

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