Carbon Sequestration and Oxygen Release Capacity of Plants in the Southern Taihang Mine Restoration Region, Henan Province

Excessive mining activities in the Southern Taihang Mountain region have caused severe ecological degradation and a decline in carbon sequestration capacity. Vegetation restoration is fundamental to recovering the carbon sink function of degraded mining areas. To identify regionally dominant carbon-sequestering vegetation and enhance the carbon sink efficiency of ecological restoration, this study investigated all dominant plant species (six in total) within the restored area of the Chenzhuang Project in Jiaozuo City, Henan Province, ensuring a comprehensive representation of the vegetation status in the restoration zone. Among these species, Platycladus orientalis, Elymus dahuricus and Parthenocissus tricuspidata were artificially planted for revegetation, while Ailanthus altissima, Vitex negundo and Gleditsia microphylla were pioneer species that naturally regenerated following mine restoration. Carbon sequestration and oxygen release capacities were evaluated by measuring net photosynthetic rate and leaf area index (LAI). The results showed that the diurnal variation of net photosynthetic rate exhibited either a single-peak pattern (only in P. orientalis) or a double-peak pattern (in the other species); The mean net photosynthetic rates ranged from 1.81 to 8.91 μmol·m⁻²·s⁻¹, while LAI values ranged from 1.37 to 2.56; Net assimilation per unit leaf area varied between 68.83 and 355.31 mmol·m⁻²·d⁻¹. E. dahuricus exhibited the highest mean photosynthetic rate and net assimilation per unit leaf area, whereas P. orientalis showed relatively low values. Cluster analysis of carbon sequestration and oxygen release capacity classified the six species into three levels: E. dahuricus was categorized as Level I with strong carbon sequestration and oxygen release capacity; A. altissima and V. negundo were classified as Level II with moderate capacity; and P. orientalis, P. tricuspidata, and G. microphylla were grouped as Level III with relatively weak capacity. Overall, the artificially planted species E. dahuricus demonstrated superior carbon sequestration efficiency compared with naturally regenerated pioneer species, while the pioneer species exhibited higher carbon sequestration capacity than P. orientalis. This study represents the first comparative assessment of carbon sequestration and oxygen release capacities between artificially planted vegetation and naturally regenerated pioneer species in a restored mining area of the Southern Taihang Mountains. The findings provide a synergistic vegetation configuration strategy of “artificial planting + natural conservation” for ecological restoration in mining areas of the Southern Taihang region. It is recommended that E. dahuricus be prioritized in restoration practices and combined with species such as A. altissima and V. negundo. to maximize the carbon sink benefits of ecological restoration.