Objective  The aims were to find out the effect of different stand types on soil nutrients in the Geqiugou watershed.

  Method  The 8-year-old Pinus sylvestris forest, mountain peach forest, seven plots of pine forest, tree-shrub forest, mixed forest of pine and arborvitae, mixed forest of sea buckthorn and apricot, and control area without planting plants (CK treatment) were selected as the research objects, and the soil organic of different stand types at different soil depths was determined. Total nitrogen, available phosphorus and available potassium contents were used to study the change law of soil nutrient contents, and to explore the effect relationship between different stand types and soil improvement.

  Result  The results showed that soil organic content of different stand types at 0 - 20 cm and 20 - 40 cm depth increased by 11.11% - 53.55% and 9.91% - 49.56%, and soil total nitrogen content was increased by 4.86% - 54.15% and 10.38% - 59.73%, soil available phosphorus content increased by 36.84% - 160.53% and 45.71% - 117.14%, soil available potassium content increased by 12.32% - 67.95% and 19.50% - 66.32%, respectively.

  Conclusion  Different stand types with 8-year old increased soil nutrient levels to varying degrees. Compared with the mixed forest of Poplar Caragana, P. The improvement effect was the best. In the future, on the premise of ensuring the ecological balance of the forest, the planting of the above three stand types could be appropriately increased in the Geqiugou watershed. The research has provided a certain reference on soil nutrient cycling of plantation under the background of carbon neutrality and the selection and breeding of plantation in the Geqiugou watershed