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Human activities and natural forces have profoundly influenced vegetation ecosystems in the Tibetan Plateau over the recent decades. However, contributions of these two driving forces to vegetation changes remain controversial, especially in the ecological barriers like the Qilian Mountains (QM) in the northeast where many protecting measures and strategies were applied to enhance ecosystem stability and services. Our study employed a process-based model and a multi-perspective assessment method to determine dominant drivers of vegetation changes in the QM since 2000. The result indicated that human activity changes contributed 40.74% to the significant vegetation amelioration of the QM as a whole, which is comparable to natural forces. Areas dominated by human activity changes accounted for 18.42% of the entire region, which were mainly distributed in grassland restoration area, oasis agricultural area and forestry protection area. In these areas, increased human activities (including desertified grassland restoration, agricultural irrigation and fertilization, forest protections and afforestation) mainly promoted the vegetation amelioration. Yet, natural forces resulted in amelioration in partial alpine grasslands in southeastern QM, accounting for 10.53% in area. Areas dominated by both human activity changes and natural forces, mainly in grazing grasslands, accounted for 47.80%. Variations in grazing intensity and climate jointly determined fluctuations in vegetation therein. Additionally, there remained 23.25% areas lack of obvious drivers, generally with sparse vegetation. Ecological protections and agricultural measures significantly promoted the vegetation amelioration of the QM since 2000. The findings could provide essential insights for protection and construction of the ecological barriers in the Tibetan Plateau., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The ecological effect of atmospheric N deposition has become a hot research point along with intensive human activities and global climatic change. As the transition zone between the Tibetan Plateau and the arid region, the Qilian Mountains are important ecological barriers and source regions of inland rivers in northwest China. However, the quantification of N deposition in the transition zone between the Tibetan Plateau (TP) and the arid region remains unclear, primarily due to the lack of in situ measurements. Hence, an observational study was conducted on the Qilian Mountains, and precipitation data were collected. Approximately 1382 samples were collected and analyzed regarding their characteristics and environmental effects of the atmospheric N wet deposition. The annual wet deposition of atmospheric N was 10.05 kg/hm 2 , and showed a decreasing trend from the south to the north of the Qilian Mountains. NO 3 -N deposition was the main form of wet deposition of atmospheric N on the Qilian Mountains, accounting for 73.83% of the DIN deposition. Additionally, altitude, meteorological factors, and ecosystem types were found to influence the wet deposition of atmospheric N. The contribution of NO - -N deposition was the main form of wet deposition of atmospheric N on the Qilian Mountains, accounting for 73.83% of the DIN deposition. Additionally, altitude, meteorological factors, and ecosystem types were found to influence the wet deposition of atmospheric N. The contribution of NO 3 - -N to the wet deposition of atmospheric N in meadows, forests, grasslands, farmlands, and towns was 48.38%, 71.55%, 77.54%, 69.61%, and 82.84%, respectively. This study provides a scientific basis for the effective management and sustainable development of environmental protection in the transition zone between the TP and the arid region. The results showed that relevant policies, as well as scientific and governmental measures, could contribute to reducing N deposition effectively. However, the further mitigation measures should be proposed and strictly enforced., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Grassland management is one of the most important means to address grassland degradation on the Qinghai-Tibet Plateau, but at present, the primary goal is still to improve grassland productivity, and little research has been conducted on grassland management based on its ecosystem service relationships. Based on remote sensing and meteorological data, we calculated and analyzed the spatial and temporal changes, trade-offs and synergistic relationships between livestock production and water retention services in alpine grassland on the southern slopes of the Qilian Mountains (SSQM), and designed a grazing management plan for sustainable development in the region. The results showed that the value of livestock production and water retention services of alpine grassland decreased from east to west, and their relationship is dominated by synergy and complemented by trade-offs. The synergistic relationships are concentrated in the Qinghai Lake Basin in the south and the river valleys in the north, while the trade-offs are scattered in the steeper terrain in the western and eastern parts of the study area. The scenario of preserving all water retention services and losing some livestock production services is sustainable. Based on this scenario we divided the alpine grassland of the study area into maintenance grazing, rotational grazing and grazing exclusion of 65.8%, 32.0% and 2.2%, respectively. Our study demonstrates that ecosystem service relationships have the potential to guide grassland management, and the results will provide new approaches to alpine grassland management., (Copyright © 2021 Elsevier Ltd. All rights reserved.)