Abstract:

Ground substrate survey is novel in the survey and monitoring of natural resources, representing a new field in modern geological survey, where classification serves as the prerequisite for this survey. To quickly understand the spatial pattern of the ground substrate at the national or provincial scale, it is essential to investigate classification schemes that incorporate concepts from related disciplines and existing survey data. Texture is the combination of different particles within the ground substrate. Characterizing ground substrate classification through texture helps clarify its ecological function in supporting forests, grasslands, and other ecosystems. In the Xinjiang Uyghur Autonomous Region of China, with its vast territory and complex landforms, geomorphological type is the primary factor controlling the spatial differentiation of ground substrate. This study utilized multi-source information, including Digital Elevation Model, Land Use/Cover Change data, high-resolution soil maps, and vegetation index data. Consequently, we established a three-level geomorphologic regionalization and a validated geomorphology-based classification scheme for characterizing ground substrate texture. This approach helped to obtain the spatial heterogeneity of ground substrate textures in Xinjiang. There are 47 geomorphological types based on differences in slope, relief, elevation, and geological genesis in Xinjiang. These types consist of 6 first-level regions, 27 second-level regions, and 1,056 third-level regions. The number of third-level regions in mountainous areas is higher than that in basin areas, with medium-altitude hills being the most widely distributed third-level regions. Notably, medium-undulating mountains are the most extensive third-level geomorphological types in mountainous areas, while medium-altitude wind-accumulated landforms are the most extensive in basin areas. For most of the geomorphological types, the average vegetation rooting depth was less than 100 cm, hence soil information within the 0-200 cm depth range was sufficient to describe the ground substrate structure. The mean value of the number of major soil texture types within 0-200 cm depth range for different geomorphologic types was 70.9%, indicating the reliability of using geomorphology-based ground substrate texture classification. Silty loam, sandy, and gravel are the main ground substrate textures, accounting for 49.6%, 27.1%, and 10.3% of the total area of Xinjiang, respectively. Silty loam is the texture classification with the highest quantity and quality of forest, grassland, and arable land resources in Xinjiang. This scheme considers both hydrothermal conditions and physical properties, making it helpful for evaluating the suitability of natural resources and territorial spatial planning in Xinjiang.

Key words: Xinjiang, geomorphologic regionalization, ground substrate texture classification, natural resource