In the Hengduan Mountain region, soil erosion is the most serious ecological environmental problem. Understanding the impact mechanism of water yield and soil erosion is essential to optimize ecosystem management and improve ecosystem services. This study used the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) and Revised Universal Soil Loss Equation (RUSLE) models to separate the relative contributions of land use and climate change to water yield and soil erosion. The results revealed that: (1) Although soil and water conservation has been strengthened in the past 25 years, both water yield and soil erosion increased from 2010 to 2015 due to the conversion of woodland to grassland, which indicates that continuous benefits after the implementation of ecological restoration projects were not obtained; (2) Climate change played a decisive role in water yield and soil erosion changes in the Hengduan Mountain region from 1990 to 2015, and soil erosion was not only related to the amount of precipitation but also closely related to precipitation intensity; (3) The contribution of land use and climate change to water yield was 26.94% and 73.06%, while for soil erosion, the contribution of land use and climate change was 16.23% and 83.77%, respectively.

It is of great significance to explore landscape pattern changes around urban areas to maintain regional ecological security and encourage sustainable development. Few studies have focused on the small cities located in the mountain regions. In this study, we established an ‘urban-rural’ gradient, and combined with landscape metrics to analyze the spatial-temporal changes of the landscape pattern around cities located in the Hengduan Mountain region in China. We also explored the impacts of topography on urban sprawl using the ‘relief degree of land surface’ index. Our results showed that: (1) There was an inverse relationship between the urban sprawl and restricted topography; (2) From the city center to rural areas, the landscape dominance degree and connectivity decreased initially and then increased, while the diversity presented an opposite trend and the shape complexity increased first and then fluctuated; (3) For temporal changes, in the internal buffers, the landscape dominance degree and connectivity increased, and the shape complexity and diversity decreased. However, in the outer buffers, the landscape showed opposite trends. It is advisable to use gradient and landscape metrics to explore landscape pattern changes. Similar to cities on plains, the landscape around mountain cities exhibits a circular structure, however, it also possesses unique characteristics when facing topographic restrictions.