Large-scale afforestation can significantly change the ground cover and soil physicochemical properties, especially the soil fertility maintenance and water conservation functions of artificial forests, which are very important in semi-arid mountain ecosystems. However, how different tree species affect soil nutrients and soil physicochemical properties after afforestation, and which is the best plantation species for improving soil fertility and water conservation functions remain largely unknown. This study investigated the soil nutrient contents of three different plantations (Larix principis-rupprechtii, Picea crassifolia, Pinus tabuliformis), soils and plant-soil feedbacks, as well as the interactions between soil physicochemical properties. The results revealed that the leaves and litter layers strongly influenced soil nutrient availability through biogeochemical processes: P. tabuliformis had higher organic carbon, ratio of organic carbon to total nitrogen (C:N) and organic carbon to total phosphorus (C:P) in the leaves and litter layers than L. principis-rupprechtii or P. crassifolia, suggesting that higher C:N and C:P hindered litter decomposition. As a result, the L. principis-rupprechtii and P. crassifolia plantation forests significantly improved soil nutrients and clay components, compared with the P. tabuliformis plantation forest. Furthermore, the L. principis-rupprechtii and P. crassifolia plantation forests significantly improved the soil capacity, soil total porosity, and capillary porosity, decreased soil bulk density, and enhanced water storage capacity, compared with the P. tabuliformis plantation forest. The results of this study showed that, the strong link between plants and soil was tightly coupled to C:N and C:P, and there was a close correlation between soil particle size distribution and soil physicochemical properties. Therefore, our results recommend planting the L. principis-rupprechtii and P. crassifolia as the preferred tree species to enhance the soil fertility and water conservation functions, especially in semi-arid regions mountain forest ecosystems.

中文翻译：

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三种针叶林物种对半干旱山区生态系统植物-土壤反馈和土壤理化性质的影响

大规模造林可以显着改变地表覆盖和土壤理化特性，尤其是人工林的土壤肥力维持和水保持功能，这在半干旱山区生态系统中非常重要。然而，造林后不同树种如何影响土壤养分和土壤理化特性，以及哪种树种是改善土壤肥力和节水功能的最佳种植树种，仍然未知。这项研究调查了三种不同人工林（Larix principis-rupprechtii，Picea crassifolia，Pinus tabuliformis）的土壤养分含量，土壤和植物-土壤的反馈，以及土壤理化性质之间的相互作用。结果表明，叶片和凋落物层通过生物地球化学过程强烈影响土壤养分的利用：油菜假单胞菌具有较高的有机碳，有机碳与总氮的比率（C：N）和有机碳与总磷的比率（C：P）。叶片和凋落物层比L. principis-rupprechtii或P. crassifolia多，表明较高的C：N和C：P阻碍了凋落物的分解。结果，与油松人工林相比，华氏乳杆菌和芸苔人工林明显改善了土壤养分和黏土成分。此外，L。principis-rupprechtii和P. crassifolia人工林大大改善了土壤容量，土壤总孔隙度和毛细孔隙度，降低了土壤容重，并增强了蓄水能力，与油松人工林相比。研究结果表明，植物与土壤之间的紧密联系与C：N和C：P紧密相关，并且土壤粒径分布与土壤理化性质之间存在密切的相关性。因此，我们的研究结果建议种植普氏乳杆菌和景天草作为首选树种，以增强土壤肥力和节水功能，特别是在半干旱地区的山区森林生态系统中。