Abstract: In this paper, the age-class structure of arbor populations in sample belt were described by fractal dimensions. Dynamics of age-class structure, sensibility of interfering conditions and change of stabilization, decline and increase of population's age-class structure were studied. The result show:Quercus liaotungensis always is dominant popuplation and its individuals of different age-class have wider capacity of spatial distribution at different parts in sample belt. The age-class of Fraxinus rhynchophylla tends to complex but the one of Acer mono tends to simple along the simple belt. All of arbor populations belong to younger increasing type of age-class structure. For different arbor populations, the value of increase (V_pi) and the sensibility of interfering conditions have larger variance and display approximatively negative relation with quantity of age-class of this population and spatial distribution at different parts in sample belt.

Key words: Dynamic of age-class structure, Fractal dimension, Quercus liaotungensis forest