'Urban-Rural' Gradient Analysis of Landscape Changes around Cities in Mountainous Regions: A Case Study of the Hengduan Mountain Region in Southwest China

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.