Three-dimensional ecological footprint based on ecosystem service value and their drivers: A case study of Urumqi

Natural capital is essential for human survival, continuation of modern civilization, and realization of sustainable development goals. Therefore a scientific framework is required for evaluating regional natural capital consumption and its capacity for ensuring sustainable development. Regional sustainability assessment can be conducted by applying the ecological footprint theory and modeling methods. However, traditional models focus on the production function of land, while disregarding the versatility of ecosystems and therefore cannot demonstrate the supply–demand relationship and their balance for ecological footprint based on the flows of ecosystem services. In this study, an ecological footprint model based on ecosystem service values was developed and used to measure the ecological footprint and carrying capacity of Urumqi city in China during 1995–2018. Subsequently, the partial least squares method was used to identify the factors driving the changes in the ecological footprint depth of Urumqi. The results showed that: (1) the equivalence factors of Urumqi were relatively stable, in the following order: water area (7.81) > forest land (2.08) > grassland (0.67) > cultivated land (0.35). The yield factors varied highly, in the following order: cultivated land (1.08) > forest land (0.78) > water area (0.76) > grassland (0.72). (2) During 1995–2018, the per capita ecological footprint increased by 2.83 times, ecological carrying capacity decreased by 34.74%, and ecological deficits increased by 15.76 times. Moreover, the energy land-use contribution to the deficits was larger than that of other land categories owing to its high proportion and rapid growth. (3) Within 24 years, the ecological footprint of Urumqi increased in size and depth by 1.78 and 2.45 times, respectively. Therefore, Urumqi requires approximately quadruple the current land area to meet the residents’ resource consumption demands under sustainable development. (4) The three extremely important factors influencing the change in ecological footprint depth in Urumqi were built-up area, permanent resident population, and per capita gross domestic product (GDP), with the values of variable importance in projection being 1.17, 1.15, and 1.15, respectively. Compared with the traditional model, the improved model proposed has the advantages of reducing accounting errors, reflecting product attributes, and considering land versatility. The results may facilitate the reasonable use and management of natural capital in Urumqi, thereby promoting the sustainable social, economic, and environmental development of the city. They also provide reference for the sustainable development of similar oasis cities and arid regions with high ecological security risk.