[Effects of thinning intensities on natural regeneration of Larix principis-rupprechtii plantations].

) plantations in Daqing Mountains of Inner Mongolia during the growing seasons of 2023 and 2024, which were thinned at different intensities (0-90%) 20 years ago. We elucidated the mechanisms of thinning affects on natural regeneration of larch plantations by structural equation model. The results showed that the density and frequency of natural regeneration seedlings and the sapling ratio increased significantly with increasing thinning intensity. Thinning directly promoted natural regeneration, and indirectly facilitated it by improving the understory light environment and litter conditions. The factors influencing natural regeneration in descending order of standardized total effect coefficients were: thinning intensity (0.822) >canopy closure (-0.771) >litter thickness (-0.527) >total understory light (0.424) >litter accumulation (-0.421) >herbaceous plant cover (-0.288) >tree height (0.119) >soil moisture (0.092). From the perspective of promoting natural regeneration and stabilizing community structure, we recommend to conduct thinning at an intensity of no less than 40%, adjust canopy closure to 0.50-0.60, and timely remove excessive litter.