Abstract: Based on the knot analysis data of 95 sample trees in 19 sample plots, the number of rings of knots in different development phases was analyzed for larch(Larix gmelinii) plantations with different ages, stand densities and sites. The results showed: The knots of larch plantation produced perceptible rings during normal growth. The number of perceptible rings ranged from 1 to 36, with an average of 10.9. The relationship between perceptible rings and length of knots was positive linear. It is common that the knots of larch plantation had missing rings, the number of missing rings was from 0 to 19(mean value is 3.44). The missing rings increased with knots length increasing. During this period the branches made no contribution to the growth of trees, so this was the right time for artificial pruning. The time of knots between death and occlusion was 12 years on average, which was about 51% of their total growth time. The loose knots produced during this period would be a great impact on the quality of wood.

Key words: Larix gmelinii plantation, knot, development phases, number of rings