Abstract:Vegetation restoration is the main restoration measure of degraded ecosystem, and it is also an important and direct activity for human to improve regional ecological environment. At present, a lot of studies have been carried out on soil physical and chemical properties and biological characteristics in arid and semi-arid areas according to different vegetation restoration methods. However, there are few reports on the effects of Pinus sylvestris var. mongolica plantation construction on the changes of soil particle composition in Horqin sandy land. Therefore, 20 plots of Pinus sylvestris var. mongolica plantation at different growth stages (including young, middle-aged, mature and over-mature forests) in Zhanggutai area of Liaoning Province were used as the research objects and 7 adjacent natural grasslands were used as control, the effects of construction of Pinus sylvestris var. mongolica plantation on soil particle composition in 0-100 cm soil layer in sandy land were studied. The results showed that after afforestation in sandy grassland, the content of fine soil particles (< 0.05 mm) in different soil layers increased, and had a significant increasing trend in 0-10 cm layer. The fine soil particles variation decreased gradually with the increase of soil depth (except for young forest), but the composition of soil particles in Pinus sylvestris var. mongolica forest was still sand. The content of soil clay and silt is very low (only about 5%). The fine soil particles variation increased gradually with the increase of stand age in 0—10 cm soil layer, where there was no significant change in 10—100 cm soil layers. The change of fine soil particle content was positively correlated with soil water content in 10—100 cm soil layers, and negatively correlated with soil total potassium in 0—10, 20—40 and 80—100 cm soil layers, and positively correlated with soil organic carbon in 20—60 cm soil layers. There was positive correlation between fine soil particle content and soil total phosphorus in 10—40 cm soil layers and negative correlation in 80—100 cm soil layer.Therefore the construction of Pinus sylvestris var. mongolica plantation can effectively increase the content of fine soil particles in soil and has significant effect on the surface soil layer, however, in the short term, the composition of soil particles will not change significantly. The improvement of soil particle composition in Pinus sylvestris var. mongolica plantation will also change other soil factors accordingly.