Effect of Thinning on the Spatial Structure of a Larix gmelinii Rupr. Secondary Forest in the Greater Khingan Mountains

• Published in: Forests Vol. 9; no. 11; p. 720
• Main Authors: Zhang, Tian, Dong, Xibin, Guan, Huiwen, Meng, Yuan, Ruan, Jiafu, Wang, Zhiyong
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2018
• Subjects: Biodiversity; comprehensive evaluation; Density; Entropy; Evaluation; Forest management; Forestry; Forests; Horizontal distribution; Larix gmelinii; Larix gmelinii Rupr. secondary forest; Mountains; Optimization; Spatial distribution; spatial structure; Studies; Thinning; Trees; Beijing China; Norway; China
• ISSN: 1999-4907; 1999-4907
• DOI: 10.3390/f9110720

Thinning is an important way to adjust and optimize the spatial structure of forests. The study of its impacts support a better understanding of the succession process of secondary forests after interference. To study the changes in forest spatial structure under different thinning intensities and stand densities, we considered five thinning intensities including unthinned (0%), low (3.4%, 6.2%, 12.5%), medium (16.8%, 20.9%, 25.5%), high (34.4%, 40.0%, 47.9%), and extra-high (50.6%, 59.9%, 67.3%) intensity. In addition, three different stand densities for each degree of thinning intensity. The results showed that the most horizontal distribution patterns after thinning were uniform distribution and near-uniform random distribution. Most of the trees were not mixed while several were mixed to an above medium degree. The effect on dominance of thinning was not significant and the overall plots were in the middle level. The tree density was in the sparse status. Competitive pressure on the reference tree was reduced. Thinning intensity and stand density affected stand spatial structure to different degrees. There were no obvious pattern under different thinning intensities and it was optimal at approximately 1600 trees/ha. As thinning intensity increased, the impact tended to decrease first and then increase under certain stand density. The improvement was greatest when thinning intensity was low. By analyzing the stand’s spatial structure after thinning, the unreasonableness of the stand’s spatial structure can be found, which provides the basis for optimizing management measures. We used the AHP-entropy to weigh the importance of each spatial structure parameter and we proposed a comprehensive distance evaluation index based on the optimal value obtained in order to perform a comprehensive evaluation of a forest’s spatial structure.