As an important means of curbing soil degradation, afforestation has a profound impact on regional soil properties and quality. However, it is still unclear regarding how to conduct a systematic assessment of soil properties and soil quality and the impact of vegetation characteristics and plant functional traits in leguminous plantations with different afforestation years in drylands. Therefore, we investigated the vegetation characteristics and determined the functional traits of leaves and roots and the soil physicochemical properties of Caragana korshinskii plantations with 13, 35, and 55 years. The results showed that tree height; crown diameter (CD); root dry matter content; root water content; soil clay, silt, and sand contents; bulk density (BD); soil water content; soil organic carbon (SOC); total nitrogen (TN); available nitrogen; total phosphorus (TP); available phosphorus (AP); and soil quality index (SQI) changed significantly with an increase in afforestation years. Although the specific leaf area did not show a significant variation, it had a significant negative effect on soil properties and SQI, except for soil sand and BD. Soil sand and BD decreased with the afforestation succession, but the succession pattern of soil clay, silt, SOC, TN, TP, and AP was 13 years < 35 years < 55 years, and SQI increased from 0.20 (13 years) to 0.77 (55 years). This indicated that long-term legume afforestation led to the transformation of soil texture from silty loam to silt and significantly improved the soil properties and quality in the study area.

Assessing the characteristics of runoff changes and quantifying the contribution of influencing factors to runoff changes are crucial for water resources management and sustainable development in the source region of the Yellow River (SRYR). The intra-annual distribution of runoff depicted a double-peak effect. The first runoff peak in July was primarily influenced by precipitation, which did not completely flow after falling to the ground. However, some water was stored in the active layer of permafrost and released in September resulting in the second runoff peak. The contributions of precipitation and temperature to the runoff changes were 74.2% and 25.8%, respectively. The runoff peaks advanced by 15 and 6 days for the first and second peaks, respectively, owing to the influence of the cryosphere change. Principal component analysis revealed that the contributions of climate change and human activity to runoff fluctuations were 72.9% and 27.1%, respectively, during 1961-2018, indicating that hydrological processes were mainly influenced by climate change in the SRYR. The combined effect of climate change created a warm and dry trend after 1990, indicating a spatial distribution of wetness in the northwest and aridity in the southeast of the SRYR.