PJB-2024-358
Effects of conservation thinning on secondary mixed conifer forest growth and species diversity
Zixuan Zhou, Deling Yang, Lei Huang, Sudipta Saha and Fan Yang
Abstract
Conservation of plant species diversity is a global issue in both secondary and natural forests. To clarify the effects of different conservation thinning intensities (10, 15, 20, 25, 30, and 35%) on forest growth and species diversity, data from seven mixed forest plots in Dongfanghong Forest Experimental Bureau, Heilongjiang Province, China, were utilized to observe the evolution of natural mixed forests and the diversity of species in the tree, shrub, and herb layers. In all sites, apart from plot F (35% intensity of thinning), diameter at breast height (DBH) was greater than the control site six years after thinning in terms of both the cumulative growth and the yearly growth of DBH. Plot C (20% intensity of thinning) showed the highest growth, with a total DBH growth of 3.394 cm and a DBH annual growth of 0.567 cma-1. Total height growth in all plots was greater than in the control plot, with the highest increase in plot B (15% intensity of thinning). The total growth of tree height was 5.71 m in six years, and the growth of tree height in successive years was 0.95 ma-1. Therefore, it was informed that thinning could significantly affect the diameter distribution and tree height distribution of the forest stand. However, the distribution of the diameter order gradually shifted to the right with the increase in intensity of thinning, and the average productivity of the tree layer of the natural coniferous and broadleaf mixed forests could be increased by the thinning. Overall, species diversity at each thinning sample site improved, but thinning decreased the average biomass of the tree layer. This drop in biomass was proportional to the degree of thinning. Conservation thinning enhances tree productivity and species diversity, promoting large-diameter tree cultivation and natural mixed coniferous and broad second-growth forest growth
To Cite this article:
Zhou, Z., D. Yang, L. Huang, S. Saha and F. Yang. 2025. Effects of conservation thinning on secondary mixed conifer forest growth and species diversity. Pak. J. Bot., 57(6): DOI: http://dx.doi.org/10.30848/PJB2025-6(20)
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