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The study on the native distribution of Stewartia koreana in Korea was conducted using 9 sample plots of 500 ㎡ size. The native areas of Stewartia koreana in Korea were Mt. Jiri, Baekun, Kaya, Mohu, Mudeung, Namhae Keum, Naejang and Sobaek . Mt. Sobaek was located in N37° E128° 30´ of the northern part of South Korea. The distribution area of Stewartia koreana in Mt. Sobaek was 7.32㏊. The high density area of Stewartia koreana was 0.7㏊ (18.5 plants per 500㎡), the middle density area of Stewards koreana was 1.8㏊ (14 plants per 500㎡), and the low density area of Stewartia koreana was 4.8㏊ (9 plants per 500㎡). The total number of Stewartia koreana in Mt. Sobaek was 1667 plants. The number of Stewartia koreana by 14 over 10 ㎝ of diameter of breast height(DBH) was 409 plants. The number of Stewartia koreana over 20 ㎝ of diameter of breast height was 177 plants. The number of Stewartia koreana over 30 ㎝ of DBH(diameter of breast height) was 41 plants near by Hebang Falls and Seojeonam. The oldest tree of Stewartia koreana in Mt. Sobaek was that DBH, height, and age were 61㎝, 15m, and 150 years old, respectively. The studied stands in Mt. Sobaek were located mainley at the northern-western slope ranging from 600m to 900m in elevation at the cool-temperate forest zone. The slope grade of site studied was 15°∼45°. The soil texture was loam and sandy loam. Soil acidity was pH 4.6. Stewartia koreana competed mixing with Carpinus laxiflora in high density area, Quercus dentata, Carpinus laxiflora, Fraxinus rhynchophylla in middle density, and Quercus dentata, Fraxinus rhynchophylla, Quercus aliena in low density area. The successional trends of tree species seem to be Carpinus laxflora species and Stewartia koreana species in the upper layers. For estimation of tree age by counting tree ring, the regression analysis formula was Y=17.89+2.14x (r´=0.49, x=DBH ㎝). So the oldest Stewartia koreana in Mt. Sobaek was 150 years old. Stewartia koreana in high density and middle density of Stewartia koreana seemed to be affected by climatic factors. In 1991, the minimum temperate of site studied was -27.6℃. Therefore, it will be used gene source in breeding of new winter hardiness cultivars of Stewartia koreana.
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