黄土高原矿区生态修复固碳机制与增汇潜力及调控

Mechanism, potential and regulation of carbon sequestration and sink enhancement in ecological restoration of mining areas in the Loess Plateau

黄土高原矿区生态环境脆弱,科学认识黄土高原矿区生态修复固碳增汇机制、潜力对碳中和愿景目标至关重要。为此,需探究黄土高原矿区生态修复中碳汇形成的关键过程,修复的适应性和恢复力及增汇潜力,揭示矿区复垦土壤碳库稳定性机制,最终阐明矿区生态修复中固碳增汇的关键技术。结果表明:(1)黄土高原矿区生态修复碳汇形成的关键过程包含植物光合碳分配、土壤碳固持、微生物固碳和土壤呼吸等;(2)黄土高原矿区生态修复适应性总体呈东南高、西北低,适应性较差区主要分布于陕北与内蒙古和宁夏中部与内蒙古交界处。典型矿区生态恢复力指数为混交林(43.2%~100.0%)>阔叶林(49.2%~83.2%)>针叶林(47.9%~76.5%)>草地(39.1%~70.7%)>灌木草地(43.0%~69.0%)。修复年垦与土壤碳汇潜力呈正相关关系,修复10~15年时最高,混交林生态恢复耗时最长,但固碳潜力最大;(3)复垦土壤碳库稳定性机制与凋落物分解、黏土矿物交互作用、团聚体物理保护和微生物调控有关;(4)地貌重构-土壤重建-先锋植物/微生物-外源材料相耦合修复技术是黄土高原矿区生态修复固碳增汇的最优路径,有利于碳汇的长期稳定和提升。

The ecological environment of mining areas in the Loess Plateau is extraordinary fragile, so it is crucial to achieve the carbon neutral vision to scientifically understand the mechanism and potential of carbon sequestration and sink enhancement in ecological restoration of mining areas in the Loess Plateau. Therefore, it is necessary to explore the key processes of carbon sink formation, the adaptability and resilience of restoration, and the potential of increasing carbon sink in the ecological restoration of the mining area in the Loess Plateau, as well as reveal the stability mechanism of the carbon pool in the reclaimed soil of the mining area. Finally, the key technologies of carbon fixation and sink enhancement in the ecological restoration of the mining area are clarified and elucidated. The results showed that:(1) The critical processes of carbon sink formation in ecological restoration of mining areas in the Loess Plateau included plant photosynthetic carbon allocation, soil carbon sequestration, microbial carbon sequestration, soil respiration and so on;(2) The ecological restoration adaptability of the mining areas in the Loess Plateau generally presented a trend of high in the southeast and low in the northwest, while the areas with poor adaptability were mainly distributed at the border between northern Shanxi and Inner Mongolia, as well as between central Ningxia and Inner Mongolia. The order of ecological resilience of typical mining areas was shown as follows: Mixed forest(43.2%-100.0%) > Broad-leaved forest(49.2%-83.2%) > Coniferous forest(47.9%-76.5%) > Grassland(39.1%-70.7%) > Shrub grassland(43.0%-69.0%). There was a positive correlation between the remediation years and soil carbon sink potential. The highest carbon sink potential generally occurred at 10-15 years of restoration. The mixed forests spent the longest ecological restoration time, but possessed the largest carbon sequestration potential;(3) The stability mechanism of reclaimed soil carbon pool was related to litter decomposition, clay mineral interaction, aggregate physical protection and microbial regulation;(4) The coupling repair technology including landform reconstruction,soil reconstruction, pioneer plant/microorganism and exogenous material is the optimal path for ecological restoration of coal mining areas in the Loess Plateau to fix carbon and increase carbon sink, and it is also conducive to the long-term stability and improvement of carbon sink.