Abstract:

Aiming at the problems of weak tending management technology and low stand productivity of natural secondary forest of Betula luminifera, the experiments of tending and thinning at different intensities were carried out to master the influence of tending and thinning on the stand growth. Four thinning intensities: 0% (CK), 10%, 20% and 30% were set in the natural secondary forest of Betula luminifera. The influence of different thinning intensities on the stand structure such as average DBH, tree height, individual plant volume, accumulation and other stand growth, diameter distribution characteristics and spatial dominance were analyzed. The results show that: (1) when the thinning intensity is less than or equal to 30%, the average diameter at breast height, tree height, and the volume and accumulation of individual plant growth of B. luminifera forest increased with the increase of thinning intensity, among them, 30% intensity thinning has the most significant effect on stand growth, and the increase is 133.0%, 67.6%, 67.3%, and 89.5%, respectively, compared with those of CK; (2) thinning is beneficial to the growth of trees into large diameter, with the increase of thinning intensity, the proportion of trees with DBH of 4-10 cm in thinning stands of the 3 intensities is lower than that of CK stand by 2.46, 8.19, and 13.69 percentage points; thinning significantly improves the spatial dominance of stand, and the highest intensity of thinning at 30% is 0.366. In the management process of B. luminifera secondary forest, based on improving stand structure and promoting stand growth, it is suggested that 30% thinning intensity is the best for B. luminifera secondary forest with an average age of 13 years and a tree density of 2500-2900 plants/hm².

Key words: Betula luminifera, stand growth, thinning, natural secondary forest, stand structure