Mediterranean riparian ecosystems provide key ecosystem services, such as climate regulation, water quality, and flood protection. Forest degradation and exotic species are among the main human-mediated impacts in these ecosystems, yet little is known about their interacting effect on the dynamics of soil characteristics. Here, we studied the effect of species canopy on monthly soil characteristics during one year in a riparian ecosystem in Central Spain. Soil chemical and microbiological properties were monthly recorded in five vegetation types: (1) forests dominated by the N₂-fixing Alnus glutinosa, (2) shrublands dominated by A. glutinosa, (3) poplar plantations of the exotic Populus × hybrida, (4) mixed forests dominated by Fraxinus angustifolia and Salix alba, and (5) grasslands. Canopy areas showed much higher soil organic C, total N, nitrate and ammonium contents than the grassland areas. A. glutinosa forests had the highest total N, organic C, ammonium, and most probable number (MPN) of aerobic and anaerobic microorganisms followed by A. glutinosa shrublands, while mixed forests and poplar plantations had the highest nitrate content. Poplar plantations showed the lowest soil N and C content likely due to the recalcitrant litter of Populus × hybrida. N₂ fixation peaked in months that differed among vegetation types. Temporal changes in soil characteristics were mostly driven by soil moisture, although the magnitude of these changes varied between canopy species. Our study highlights the importance of protecting forested areas and planting native tree species in afforestation programmes to keep the ecological integrity of riparian ecosystems. A. glutinosa is suggested as an appropriate species to improve soil fertility and stability in restoration projects.

地中海沿岸生态系统提供关键的生态系统服务，例如气候调节、水质和防洪。森林退化和外来物种是这些生态系统中主要由人类引起的影响，但人们对它们对土壤特征动态的相互作用影响知之甚少。在这里，我们研究了西班牙中部河岸生态系统一年中物种冠层对每月土壤特征的影响。土壤化学和微生物性质每月记录在五个植被类型：由N个支配（1）的森林₂ -定影桤木，（2）通过灌丛为主A.黄，（3）外来的杨树人工林杨×矮牵牛, (4) 以白蜡和白柳为主的混交林，以及 (5) 草原。冠层区域的土壤有机碳、全氮、硝酸盐和铵的含量远高于草地区域。A. glutinosa森林的总氮、有机 C、铵和好氧和厌氧微生物的最可能数 (MPN) 最高，其次是A. glutinosa灌木林，而混交林和杨树人工林的硝酸盐含量最高。杨树人工林显示出最低的土壤N和C含量可能是由于的顽抗垫料胡杨×矮牵牛。N ₂固定在不同植被类型的月份达到顶峰。土壤特性的时间变化主要由土壤水分驱动，尽管这些变化的幅度因冠层物种而异。我们的研究强调了在造林计划中保护林区和种植本地树种以保持河岸生态系统生态完整性的重要性。A. glutinosa被建议作为一个合适的物种来提高恢复项目中的土壤肥力和稳定性。