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Girth at breast height was measured to test skewness (g_1) and kurtosis (g_2) of frequency distribution of the basal area in terms of t-test and Kolmogorov-Smirnov test for a total of forty six monocultures within Sudong and Kwhangnung area in central part of Korean peninsular in 1979 and 1980. The moncultures are about 10 to 50 years old, and four kinds; Pinus koraiensis, Larix kaempferi, Abies holophylla and Pinus rigida. Most of the sample sizes per site were ranged 70 to 110 excluding 4 sites. The number of classes interval was based on Sturges rule for each monoculture and was ranged from 5 to 10. In Sudong the range of age(yr) and basal area (㎠/tree) of the monocultures were from 10 to 20 and from 27.60 to 383, for Kwhangnung they were from 15 to 47 ans mostly 102.15 to 619.14, respectively. All 43 monocultures except 1 showed ＋g_1, which ranged from 0.3 to 2.2 except six sites. Of the total 46 sites, 23 sites showed significant ＋g_1 which includes about 10 year-old monoculture. The number of classes interval with significant positive skewness ranged from 6 to 9. The data suggest that intraspecific competition in terms of stand structure seems to appear from about 10 year-old monocultures, and it may even last to about 50 year-old one. Around 24 monocultures showed nonsignificant －g_2 except one. Most －g_2 ranged from -0.12 to -0.83. Around 20 monocltures showed positive g_2 ranging from ＋0.13 to ＋3.841. Of the 22 ＋g_2, majority of 11 were very highly significant. Of all monocultures only 5 showed significant result from Kolmogorov-Smirnov test. Of the 4 species, Larix kaempferi seems to show density stress first then Abies holophylla, and Pinus koraiensis last. Data of this study indicate that adequate number of classes intervals and sample sizes for studying intraspecific competition in terms of basal area are 6 to 9 and 80 trees rather than 12 and 100 trees, respectively. It also suggests that most of the frequency distribution of basal area class are trimodal rather than bimodal under density stress. It is proposed that the leptokurtic distribution appears before normal distribution rather than direct change from platykurtic to normal distribution of basal area for selected stages in the development of stands.
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