Abstract: A sampling plot investigation was conducted on the Quercus liaotungensis forests on Loess Plateau, China under close-to-natural management thinning 13.4% (light thinning) and 30.0% (heavy thinning). Taking the un-thinned forest as the control, the population regeneration, woodland productivity, soil fertility, and species diversity of the forests after 5 years of thinning were studied, with the community stability evaluated by calculating the subordinate function values based on fuzzy comprehensive evaluation. Comparing with the control, the regeneration potential of the forests after light and heavy thinning promoted by 14.2% and 20.2%, arbor volume reduced by 9.0% and 23.8%, shrub biomass increased by 7.3% and 12.2%, and herb biomass increased by 10.5% and 31.6%, respectively. In addition, the soil fertility and species diversity indices were higher in thinning forests than in the control. The community stability showed the order of heavy thinning forest ＞ light thinning forest ＞ un-thinned forest, suggesting that the close-to-natural management thinning 30.0% was more suitable to the management of secondary Q. liaotungensis forest on Loess Plateau.

Key words: Quercus liaotungensis, close-to-natural forest management, population regeneration, soil fertility, woodland productivity, species diversity, O₃, Quercus mongolica, leaf litter decomposition, nutrient release.