A Comparative Study on Land Use/Land Cover Change and Topographic Gradient Effect between Mountains and Flatlands of Southwest China

Topography plays an important role in restricting the formation of and change in land use/land cover (LULC) patterns. To compare the LULC change and topographic gradient effects between mountains and flatlands, the geo-informatic atlas, terrain position index, distribution index and diversity index were used to analyze the LULC patterns in Yuxi from 2000 to 2020. The results were as follows: (1) the temporal-spatial variation in LULC was obviously different. From 2000 to 2020, land use change in the flatlands was more severe than that in the mountains. The transfer amount of forestland in the mountains was the largest, with the transfer-out and transfer-in accounting for 48.53% and 31.05%. However, in the flatlands, the biggest changes were found in the transfer-out of cultivated land and the transfer-in of build-up land, which were 46.91% and 38.20%, respectively. The LULC types in the mountains changed dramatically from 2000 to 2010, while those in the flatlands changed dramatically from 2010 to 2020. (2) There were obvious differences in the topographic gradient effects. The dominant distributions of land use types in the low-terrain area were the same, but the dominance of build-up land in the flatlands and that of wetland in the mountains were the largest. In the mountains, the dominant distribution of grassland was in the medium-terrain position, while that of forestland was in the high position, and the opposite was found in the flatlands. In addition, the variation trend of the diversity index in the mountains was relatively simple, but the variation range was large, ranging from 0 to 1.677, and high diversity was mainly found in the medium- and high-terrain positions. However, the variation trend in the flatlands was complex, but only ranged from 0.918 to 1.994, and high diversity was found in the low-terrain positions. The differences in the LULC change and terrain gradient effects between the mountains and flatlands were mainly caused by natural, socio-economic and policy factors, which can provide a certain reference for differentiated land use policies for regional coordinated and sustainable development.