Spatio-temporal evolution of carbon stocks in the Yellow River Basin based on InVEST and CA-Markov models

The Yellow River Basin is an important carbon sink and carbon stock area of terrestrial ecosystems in China, and land use/cover change is the primary reason for variation in the carbon stocks. Therefore, accurately predicting future land use/cover changes and their impacts on regional carbon stocks is important for a better understanding of regional terrestrial ecosystems. This study aimed to explore the law of spatio-temporal changes in land use in the Yellow River Basin from 2005 to 2018 and to predict the characteristics of carbon stock changes under two scenarios of ecological protection and natural change in 2030. The CA-Markov model was used to predict the land use/cover spatial pattern in two scenarios:the ecological conservation scenario and the natural change scenario, based on its law in the Yellow River Basin from 2005 to 2018. The InVEST model was used to estimate the carbon stock in six phases of the Yellow River Basin from 2005 to 2030 based on the revised carbon density. The results highlighted land use change and transition among land use types. From 2005 to 2018, the areas of forest, water, and built-up land in the Yellow River Basin continued to increase, but the areas of cropland, grassland, and unused land decreased. The main transfer characteristics of land use types were from cropland to built-up land and grassland, and from cropland and grassland to forest. During the 13 years, the carbon stock of the whole basin decreased by 28.734×10 ⁶t. The simulation results of land use changes under two scenarios with the CA-Markov model showed that compared with the natural change scenario, the ecological protection scenario led to reductions in grassland and cropland in 2030, which was less than that in 2018. The expansion of built-up land was restricted under the ecological scenario, and the scale of expansion was substantially reduced, both of which facilitated the generation of ecological effects in the Yellow River Basin. Furthermore, in 2030, the carbon stocks under the natural change scenario and the ecological protection scenario were reduced by 258.863×10 ⁶t and 30.813×10 ⁶t, respectively, compared with 2018. This study provides a scientific basis for adjusting the land use structure and land use management decision-making, improving the regional carbon stock capacity, and promoting ecological civilization construction in the Yellow River Basin.