Abstract:Ecological restoration projects such as mine reclamation, desertification control, and close hillsides for afforestation, not only improve the ecological environment within the region, enhance the stability of ecosystems and carbon sequestration capacity, but also promote soil and karst carbon sequestration. However, previous studies have mainly focused on the study of soil physicochemical properties and karst carbon sequestration characteristics under different land use patterns, while there is limited research on soil carbon pools and karst carbon sequestration characteristics under different restoration measures and vegetation cover. This article takes examples from the ecological restoration of mines in Beibei, Chongqing and the desertification control area in Wushan to investigate changes in soil carbon pools and limestone dissolution rates under different land use patterns through monitoring using standard dissolution test specimens and soil sampling analysis. The study aims to explore the impacts of different ecological restoration measures on limestone dissolution rates. To avoid the influence of different limestone dissolution differences, circular standard dissolution test specimens made of pure limestone from the Devonian Rongxian Formation series in Guilin, Guangxi, were used uniformly in the experiments. By the end of June 2022, the specimens were buried in layers according to the thickness of the soil layers. When the soil layer thickness was ≥ 50 cm, four layers of standard dissolution test specimens were placed: 100 or 150 cm above the ground, 0-2 cm below the surface, 20 cm underground, and 50 cm underground. When the soil layer thickness was less than 50 cm, three layers of standard dissolution test specimens were placed. The monitoring points in Beibei were retrieved in three batches on November 7, 2022, February 9, 2023, and April 7, 2023, respectively, while the monitoring points in Wushan were retrieved in two batches on December 29, 2022, and April 4, 2023.The monitoring results showed that the content of Soil inorganic carbon (SIC) in the restoration area is relatively high, significantly higher than the content of Soil organic carbon(SOC), with an average value of about 4.5 times. There is significantly negative correlation between the content of SIC at the surface and 20 cm below the soil and the limestone dissolution rate. The content of SOC is affected by soil types, vegetation restoration duration, and other factors. The longer the restoration period and the more flourishing the vegetation, the higher the SOC content. It shows that the mine restored for 1-4 years < the orchard restored for 5 years < the desertification control area restored for 10 years < the orchard restored for 20 years < the forestation area developed from tree planting on mountain slopes restored for 20 years, but the correlation with the limestone dissolution rate is not significant. The dissolution rates in the air and on the surface are influenced by physical weathering and chemical weathering, with higher dissolution rates than underground during the monitoring period. As the monitoring duration increases, the dissolution rates underground and on the surface increase significantly, while the dissolution rate in the air decreases. Different restoration measures also result in different underground limestone dissolution rates, showing that for the mine restoration area in Beibei, Laurel > Laurel (orange trees) > Laurel (peach trees) > Pepper trees > plum trees; for the ecological restoration area in Wushan, forested areas for desertification control > forestation areas on mountain slopes > orchards for desertification control. In summary, in future ecological restoration efforts, the selection of vegetation types and restoration measures can be used to increase karst carbon sequestration effects.