Synergistic benefit analysis of carbon sink capacity and biodiversity function of artificial ecosystems in mining reclamation sites

Land reclamation in mining areas is an inevitable measure to accelerate the restoration of biodiversity, promote the transformation and development of mining areas, and realize the transformation of carbon sources into carbon sinks. There are few studies focused on the quantitative assessment of carbon sink capacity and biodiversity restoration of artificial ecosystems and their synergistic effects in reclaimed lands. The dumps in Heidaigou open-pit mining area of Jungar Banner was taken as the research area, and the carbon sinks of vegetation and soil of the reclaimed land were calculated by combining the sample plot survey and remote sensing data. Grey correlation analysis was carried out for each region under different restoration modes to assess the synergy between the biodiversity maintenance function and carbon sequestration capacity of artificial ecosystems of reclaimed land. The results showed that: ①The area proportions of extremely important, highly important, important, average and unimportant biodiversity in the research area were 2.28%, 8.29%, 15.67%, 25.27% and 48.50% respectively. In the artificial ecosystem of reclaimed land, the biodiversity index of trees + shrubs + herbs was higher than other vegetation restoration models, which was mainly located in the inner dump, the middle of the north dump, and the middle and south of the east side dump. The important value of biodiversity maintenance function of forest land in artificial ecosystem was higher than other land use types, and most of them were located on slope or platform edge. ②The top 9 regions in terms of vegetation carbon sink were in trees + shrubs + hers restoration mode, and the average carbon sink of this vegetation restoration model (32.224 g/(m²·a)) was higher than that of other vegetation restoration models. The average soil carbon sink of tree + herbaceous vegetation restoration mode was the highest (18.164 g/(m²·a)), followed by tree + shrub + herbaceous restoration mode (16.909 g/(m²·a)). The vegetation carbon sink (5.897 g/(m²·a)) and soil carbon sink (6.237 g/(m²·a)) under the herbaceous vegetation restoration model (mainly located in the east and north dumps) were the lowest among all restoration models. The carbon sink capacity of reclaimed land was in the trend of forest ecosystem > farmland ecosystem > grassland ecosystem. ③The grey correlation index between vegetation and soil carbon sink and the assessment results of biodiversity maintenance were 0.735 and 0.710, respectively, showing a significant correlation. The vegetation carbon sink increased with the species richness index and diversity index. The increased altitude and the reclamation period led to the greater soil carbon sink.