Spatio-temporal evolution and multi-scenario prediction of land use and carbon stock in Shangluo City from 1980 to 2020

Land use change is an important factor affecting carbon stock, and predicting the impact of future land use change on carbon stock is of great significance for the sustainable development of the carbon sink function, which can provide support for the development of local land use policies. Based on the land use data of Shangluo City from 1980 to 2020, coupled with the PLUS-InVEST model, the spatial and temporal characteristics of land use and carbon stock were analyzed from 1980 to 2020, and the land use and its impact on carbon stock under the scenarios of natural development, urban development and ecological protection were simulated in 2030. The results showed that: ① The main land use types in Shangluo City from 1980 to 2020 were grassland and forest land, accounting for more than 76% of the total, in which the area of forest land continued to grow in general, and the water area decreased abnormally in 2010 due to the expansion of construction land caused by urbanization. In the pst 40 years, a total of 1064.02 km² of land had been transferred, and forest land was mainly from grassland and cropland, reflecting the effectiveness of the policy of returning farmland (grass) to forest. ② From 1980 to 2020, the carbon stock in Shangluo City showed a trend of increasing, decreasing and then increasing, with an overall increase of 10.91×10⁵ t. The spatial distribution of carbon stock was basically consistent, showing a distribution pattern of “high in the south, low in the north and concentrated in the hinterland”, and the areas of carbon stock increasing were in the southwestern and eastern parts of Shangzhou District and in the northwestern part of Zhen'an County. ③ Compared with 2020, under the natural development scenario, the areas of forest land, water area, construction land and unutilized land increased in 2030, among which the area of forest land increased the most, reaching 190.66 km², while the area of cultivated land lost seriously; under the urban development scenario, the areas of all categories except grassland were increasing; under the ecological protection scenario, cultivated land, grassland and forest land had reached a balance. ④ Compared with 2020, the carbon stock of Shangluo City in 2030 under the natural development scenario, urban development and ecological protection scenarios increased by 18.75×10⁵ t, 1.18×10⁵ t and 1.94×10⁵ t respectively. Under the natural development scenario, the growth of forested land relied on the degradation and transformation of cropland and grassland; under the urban development scenario, the total carbon stock was lower than that under the other scenarios; under the ecological protection scenario, due to the implementation of the ecological protection policy in Qinling Mountains and the establishment of ecological protection zones, the carbon stock of each category reached a balanced state.