Abstract: Spatial structure of Larix olgensis plantation was studied based on the pertree survey data of sampling plot ML707 and the common characteristics of low mixture degree and uniform distribution in L. olgensis plantation. In consideration stand competition mechanism and the utilization of the nutrition space of the crown, this article proposed a new method using Hegyi competition index(CI), Growth space index(GSI) and Growth space competition index(GSCI) to analyze and optimize the spatial structure. Further comparisons of stand spatial structure were made in terms of different selective cutting intensity. The results showed that the optimal Selective cutting intensity is about 14 percent at which the optimization of forest spatial structure is achieved. After optimization, the forest competition situation reduced, nutrition space utilization increased and forest spatial structure got improved.

Key words: optimization of forest spatial structure, Hegyi competition index, growth space index, growth space competition index, selective cutting intensity