Abstract: The results of age structure study on virgin Larix gmelini forest with different disturbed levels show that the dynamics of age Structure of one generation stands is characterized by the increase of population density and age range at young stage and by the decrease of age range during the course of natural thinning at mature and old stages. Multigeneration stands are patchy mosaics in different onegeneration stands, in which, old and young generation populations have a less age variance, and middle -aged or mature generation populations have a greater age variance. In mixed Betula platyphylla and Larix gmelini stands, the mean age of Betula platyphylla is 5-15 years older than that of Larix gmelini because of its earlier colonization at early stage, but after 50 to 70 years, that of the latter is greater due to the death of older individuals of the former.

Key words: Age structure, Larix gmelini, Betula platyphylla, Stand development dynamics