Thinning Effects on Stand Structure and Carbon Content of Secondary Forests

Abstract

In, this study, we analysed the effects of thinning on stand structure and carbon stocks for a mixed conifer and broadleaf natural secondary forests in the Small Khingan Mountains, China. Stand structure and carbon stocks were assessed in trees from unthinned control (CK), lightly thinned (LT), moderately thinned (MT) and heavily thinned (HT) treatments. Results showed that the heavier the thinning, the larger the crown area became. Under the MT treatment, trees tended to be evenly distributed when compared to trees under the other treatments. All the trees of the LT and HT treatments were mixed strongly compared to those of the CK treatment. As the thinning intensitiy increased, the distributions of size differentiation and crowding degree gradually decreased. As a result, the competitive pressure diminished, and more dominant trees emerged. In addition, there was a significant positive correlation between individual tree carbon stock and canopy under all treatments. Carbon tends to accumulate in individuals with a random distribution, sparse spacing, strong mingling index and large competitive advantage. However, the results varied slightly under the HT treatment. Individuals in a dominant position occupied abundant resources and great niche space.

Evaluation of Ecological Function Restoration Effect for Degraded Natural Forests in Xiaoxinganling, China

“…In this study, we selected more representative indicators based on the comparative analysis of previous studies to establish an evaluation index system for ecological restoration in degraded forests in Xiaoxinganling, Heilongjiang Province, China. The 43 indicators selected in this study were correlated with each other, indicating that the index system could reflect the main characteristics of the forest ecological restoration system in a comprehensive way [59,60]. However, the evaluation index system had some shortcomings and requires in-depth research and exploration to (1) construct a long-term continuous observation network for evaluation indexes for the degraded forest ecosystem in China [61,62]-this would allow for long-term monitoring, comparison, and assessment of different stages of forest ecological restoration; (2) strengthen the research on the evaluation index system for forest ecological restoration in terms of forest ecosystem functions and services; (3) combine remote sensing analysis with sample plot investigation to analyze the spatial distribution of the evaluation index system for forest ecological restoration and its ecological process on a regional scale.…”

Optimizing the Spatial Structure of Metasequoia Plantation Forest Based on UAV-LiDAR and Backpack-LiDAR

“…In this study, the widely used four-neighbor method was used to determine the spatial structural unit of the stand, i.e., a central tree was considered the object tree, and then the four standing trees closest to it horizontally were selected as competing trees to form a spatial structural unit [46,47]. At the same time, in order to avoid edge effects, the area 5 m from the boundary line of the sample plot was set as a buffer area, and trees within the buffer area only participated in the calculation as competing trees of the object trees, but not as object trees [48][49][50].…”