To provide theoretical and technical support for the sustainable management and soil fertility maintenance of larch plantations.

Larix olgensis plantations with basically the same site conditions were selected. In 2018, selective cutting operations with different intensities (25%, 35% and 45%) were carried out according to the stock volume, and non-selective cutting was set as the control. Subsequently, three fixed sample plots were set up in the stands with different selective cutting intensities. In August 2023, after five years of selective cutting operation, the coverage thickness, standing stock, soil physical and chemical properties of litters were measured in each plot. Through single factor analysis of variance, Mantel analysis and structural equation modeling, the changes of litter cover thickness, standing stock and soil physical and chemical properties under different selective cutting intensities and their relationships were studied.

After 5 years of selective cutting, the litter cover thickness decreased by 17.4%, 30.3%, and 31.0% at 25%, 35% and 45% selective cutting intensities, respectively, compared to the control stand. The undecomposed litter layer thickness decreased by 32.7% and 36.1% at 35% and 45% selective cutting intensities, respectively, compared to the control stand. The semi-decomposed litter layer thickness decreased by 25.7%,44.2%, and 43.4% at 25%,35%, and 45% selective cutting intensities, respectively, compared to the control stand. High-intensity selective cutting (45%) significantly reduced soil bulk density in the 0-10 cm layer by 17.7% compared to the control. Moderate-intensity selective cutting (35% and 25%) also reduced soil bulk density in the 20-40 cm layer, with reductions of 15.0% and 11.0% respectively. Soil moisture content increased by 40.8% (0-10 cm), 21.8% (10-20 cm), and 18.7% (20-40 cm) after high-intensity selective cutting compared to the control. The maximum soil compaction degree in 0-40 cm soil layer was 785.0 kPa in control forest,724.4 kPa in 25% selective cutting forest, 525.6 kPa in 45% selective cutting forest and 503.9 kPa in 35% selective cutting forest. Under the moderate selective cutting (35%), the soil pH, total nitrogen, total phosphorus, organic carbon and hydrolyzable nitrogen in the 0-10 cm soil layer increased by 5.5%, 21.7%, 39.8%, 45.4% and 51.3% respectively compared with the control. Under the high intensity (45%) selective cutting, the contents of available potassium and available phosphorus in the 0-10 cm soil layer increased by 30.0% and 60.4% respectively compared with the control. The results of structural equation modeling showed that selective cutting had a significant positive effect on soil moisture content and soil chemical properties, and a significant negative effect on soil bulk density, litter cover and litter stock, and also had a significant negative effect on soil chemical properties through changing litter cover and litter stock.

Selective cutting management can significantly reduce the accumulation of litter on the surface of forest land, improve the microenvironment in the stand, and be beneficial to the decomposition of litter such as larch needles on the surface. After selective cutting with medium and high intensity (35%, 45%), it can accelerate the decomposition of litter, effectively promote the circulation of soil nutrients, and play an important role in maintaining soil fertility and preventing soil acidification.