Landscape and Soil Erosion Changes Along Different Types of Road Over the Past 30 Years in the Largest Loess Tableland of China

Road construction, as a product of modern civilization, can alter landscape patterns and accelerate erosion, especially in the loess tableland area of China with fragile eco-environment. Different types of road could change land surface and increased soil erosion in different ways, while knowledge about this topic is limited. In this study, our objective is to evaluate the landscape and soil erosion changes along different types of road in the largest loess tableland of China. Results showed that: (1) The land use type became more diverse along the three types of road in 1990–2020, leading to increased landscape fragmentation and spatial heterogeneity. (2) Different types of road had different proportions of soil erosion values. In the expressway and provincial road, the proportion of low soil erosion values (below 100 t ha⁻¹ yr⁻¹) was > 70% in 1990–2020; in the national road, the proportion of low erosion values (below 100 t ha⁻¹ yr⁻¹) was > 50%. (3) In 1990–2020, soil erosion increased with the increase of road-induced landscape fragmentation along the three types of road. For the expressway, soil erosion value increased from 91.5 to 98.5 t ha⁻¹ yr⁻¹ between 1990 and 2020; for the national road, soil erosion value increased from 174.5 to 184.8 t ha⁻¹ yr⁻¹; and for the provincial road, soil erosion value increased from 93.7 to 97.1 t ha⁻¹ yr⁻¹. (4) Effective soil and water conservation programs could mitigate erosion. Compared with the simulated soil erosion value, the actual soil erosion value decreased along the expressway, national road, and provincial road by 1.21, 3.67, and 2.96 t ha⁻¹ yr⁻¹, respectively, between 2005 and 2020. This study emphasizes the importance of road in aggravating erosion and the effectiveness of soil and water conservation programs in mitigating soil erosion within the loess area.