Ecological security is of central significance for maintaining the integrity and stability of regional ecosystems. Nevertheless, current academic research systematically studying the complex driving mechanisms behind ecological security is deficient. Therefore, this study utilised ecological sources (ESs) and ecological resistance surfaces (ERSs) to calculate and obtain the Ecological Suitability Index (ESI), thereby reflecting the ecological security status. The drivers of ESI in different areas of the Yellow River Basin (YRB) from 1990 to 2020 were explored using the random forest (RF) model and GeoDetector. The results of the study show that: (1) according to the results of the RF model, LANDUSE, NDVI, and PRE are the most important driving factors of the ESI in the upper (UYR), middle (MYR), and lower (LYR) reaches of the YRB; (2) according to the results of GeoDetector factor detection, in the UYR and MYR, the ESI is primarily influenced by natural factors such as NDVI and PRE, showing particularly significant impacts in 2010 and 2020; (3) in the LYR, the ESI is mainly influenced by NDVI, but the degree of influence from socioeconomic factors has significantly strengthened. This study provides a decision-making direction for ecological protection and coordinated development in the YRB.

Carbon storage (C-storage) is a critical indicator of ecosystem services, and it plays a vital role in maintaining ecological balance and driving sustainability. Its assessment provides essential insights for enhancing environmental protection, optimizing land use, and formulating policies that support long-term ecological and economic sustainability. Previous research on C-storage in the Yellow River Basin has mainly concentrated on the spatiotemporal fluctuations of C-storage and the investigation of natural influencing factors. However, research combining human activity factors to explore the influences on C-storage is limited. In this paper, based on the assessment of the spatiotemporal evolution of C-storage in the region along the Middle and Lower Yellow River (MLYR), the influences of anthropogenic and natural factors on C-storage were explored from the perspective of sustainable development. The findings reflected the relationship between socio-economic activities and the ecological environment from a sustainable development perspective, providing important scientific evidence for the formulation of sustainability policies in the region. We noticed the proportion of arable land was the highest, reaching 40%. The increase of construction land because of the fast urbanization mainly came from arable land and grassland. During the past 15 years, the cumulative loss of C-storage was 71.17 × 10⁶ t. The high-value of C-storage was primarily situated in hilly areas, and the area of C-storage hotspots was shrinking. The aggregation effect of low-value C-storage was strengthening, while that of high-value C-storage was weakening. The dominant factors (q > 0.5) influencing the spatiotemporal variation of C-storage in the region along the Middle Yellow River (MYR) were temperature and precipitation, while the primary factor in the region along the Lower Yellow River (LYR) was temperature. Overall, meteorological factors were the main determinants across the entire study area. Additionally, compared to the MYR, anthropogenic factors had a smaller impact on the spatiotemporal evolution of C-storage in the LYR, but their influence has been increasing over time.