Effects of Selective Cutting on the Structure of Natural Forest in Burqin Mountainous Land.

In order to explore the structural changes of forest land after selective cutting and provide a basis for the restoration of important species such as Larix sibirica, 2 different types of communities of natural forest in Berqin area in Altai mountain were took as materials. The important value method and diameter class distribution method were used to study the species composition, diameter class structure in the arbor layer, the composition, number and height characteristics of renewed seedlings after the Larix sibirica had been felled. The investigated of the plot showed that Larix sibirica was the dominant species in 2 communities before felling. The important value of Picea obovata in height thinning (ZT) was 65.30, which was absolutely dominant, and the imporatnt value of Larix sibirica in height thinning (HT) ranking first with 56.70 in community I. Abies sibirica had the largest important value for 61.05 in community II after 30 years selective felling. With the increased of cutting intensity, the diameter distribution of trees shifted to a larger diameter class, small-diameter grades accounted for 77.80% in LT and the number of large-diameter trees accounted for 64.80% in HT. The regeneration characteristics of different community types were different after selective felling. Picea obovata seedlings accounted for 61.00% of light thinning and 77.00% of height thinning for community I, with the increased of cutting intensity, Larix sibirica seedlings significantly increased. The seedling height level of light thinning was concentrated in <30 cm, while it was mainly concentrated in 30-60 cm for height thinning. Abies sibirica seedlings accounted for the vast majority for 92.00% but Picea obovata seedlings accounted for merely in community II. Generally speaking, after selective felling, the regeneration ability of Abies sibirica and Picea obovata were stronger than that of Larix sibirica, and gradually replaced Larix sibirica as the predominant species; the higher the intensity of selective cutting, the better effects of natural regeneration of Larix sibirica. It was suggested that sufficient light conditions might be needed for natural regeneration. [ABSTRACT FROM AUTHOR]