Abstract: Taking the off-site preservation forest 9119B of Larix olgensis in Qinshan forestry centre in Linkou, Heilongjiang province as the materials, the growth variation of the dominant and inferior tree populations were analyzed. The results showed that there was no significant difference between the dominant and inferior tree populations, while rich variations existed in height, diameter and volume between these populations. The volume variation coefficient was the richest one, followed by the diameter and the least is the height, the coefficients were 46.24%, 19.82% and 12.25%, respectively. These three coefficients of dominant population were 12.98%, 20.77% and 49.36%, while the inferior population was 11.47%, 18.79% and 43.16%. The variations of the dominant tree population were respectively 1.51%, 1.98% and 6.2% higher than the inferior ones at height, diameter and volume. There were significant differences between these populations by the variance analysis. According to the analysis, we selected 6 families (856, 859, 563, 552, 567, 864), 3 were dominant tree populations and 3 were inferior tree populations. The average volume of these 6 families were 0.022 3, 0.018 6, 0.016 8, 0.016 4, 0.016 2 and 0.015 9 m³ bigger than the average values of dominant population, while 0.018 2, 0.014 5, 0.012 7, 0.012 3, 0.012 1 and 0.011 7 m³ bigger than the inferior ones. According to the 10% selection rate among the dominant and inferior tree populations, the variation gains were 59.33%, 65.18%, 74.91%, 40.64%, 40.94% and 45.34%, respectively.

Key words: dominant tree population, inferior tree population, genetic variation, family selection