Evaluation of suitability, adaptability, and reserve potential of construction land on the Qinghai-Tibet Plateau

Construction land is the main carrier of human activities such as production and living. Conducting the suitability evaluation of construction land on the Qinghai-Tibet Plateau (QTP) holds the significant implications for harmonizing the relationship between ecological preservation and human activities, as well as promoting the optimization of population and industrial spatial layout. However, there are no relevant studies which provide a complete assessment of the construction land suitability (CLS) on the QTP. In this paper, we developed a model- based CLS assessment framework coupling of patterns and processes to calculate the CLS across the entire QTP based on the CLS evaluation model. Then, using the land-use data of 1990, 2000, 2010, and 2020, we examined the adaptability of existing construction land to the assessment result of CLS through the adaptability index and vertical gradient index, and further analyzed the internal limiting factors of maladaptive construction land. Finally, we calculated the potential of reserve suitable construction land. This article includes four conclusions: (1) The area of CLS classes, including highly suitable, suitable, moderately suitable, marginally suitable, and unsuitable, are 0.33×104 km2, 10.42 ×104 km2, 18.06×104 km2, 24.12 × 104 km2, and 205.29 × 104 km2, respectively, accounting for 0.13%, 4.04%, 7.00%, 9.34%, and 79.50% of the total land area, respectively, with the unsuitable class being predominant. The highly suitable, suitable, and moderately suitable classes are mainly distributed in regions such as the Qaidam Basin, Yellow River- Huangshui River Valley, Gonghe Basin, Songpan Plateau, Shigatse Valley, Lhasa-Shannan Valley, and Nyingchi Valley. (2) The construction land adaptability index are 85.16%, 85.93%, 85.18%, and 78.01% in 1990, 2000, 2010, and 2020, respectively, with an average adaptability index exceeding 80% on the QTP. The distribution of existing construction land generally conforms to the characteristics of construction land suitable space, but with a significant spatial difference. (3) From 1990 to 2020, the mal-adaptive and low-adaptive construction land on the QTP is mainly composed of rural residential land, transportation land, and special land, the proportions of urban construction land and other construction land are rapidly increasing. The vertical gradient of elevation and slope of construction land have gradually strengthened, and the spatial extent has expanded. Construction land in the southern Qinghai Plateau, western Sichuan alpine canyon region, and Qilian Mountains is subjected to constraints of both elevation and slope, while the main limiting factor in the northern Tibetan Plateau, Gangdise Mountains, and Himalayan Mountains is elevation. (4) The potential area of reserve suitable construction land on the QTP is 12.41 × 104 km2, constituting 4.81% of the total land area, with suitable and moderately suitable classes dominant. The per capita potential area of reserve suitable construction land is 9928 m2/person. The Qaidam Basin has the richest reserve of suitable construction land, while the Gonghe Basin and Lhasa-Shannan Valley can serve as preferred destinations for ecological migration. The research results can provide decision- making references for ecological migration and optimizing the spatial distribution of human activities on the QTP. © 2023 Science Press. All rights reserved.