Assessing the effects of topographic gradients on landscape patterns: The study case of Tingjiang river basin, China.

With the progress of urbanization, the natural geographical characteristics of different river basins have also undergone tremendous changes, and bring many environmental and social issues. It is of great significance to the sustainable development of river basins to reveal the relationship between topographic and landscape patterns. Therefore, we selected Tingjiang river basin, utilizing remote sensing images from 1991, 2004, and 2017, as well as the digital elevation model (DEM) data, we computed a topographic classification system consisting of four levels (Low level, Low-medium level, Medium-high level, High level). This approach enables us to study the gradient impact of topography and investigate the mechanism influencing the landscape pattern. The results show: (1) Low-medium and medium-high topographic levels are dominant in the research sites, accounting 49.35% and 38.47%, respectively. (2) Bare land showed a significant decrease while construction, cultivated, and forest land increased from 1991 to 2017. (3) Forest land is mainly concentrated in the middle-high and high-topographic levels whereas construction land, cultivated land, water area and bare land are mainly concentrated in the middle-low and low-topographic level. (4) The landscape pattern significantly varies with the topographic gradient, where the conversion to construction land is widespread in the low-topographic area, while alternation between cultivated land and forest land mainly occurs in the medium-low and medium-high topographic areas. Consequently, these findings provide insights into the impact of topography on river basin landscape pattern, which could guide sustainable development in the future.