Overview of technologies and strategies for ecological restoration of dreg fields in major construction projects in ecologically fragile areas of Southwest China
Southwest China is a critical ecological barrier in the upper reaches of the Yangtze River and is the main implementation area for major national construction projects.Owing to abundant rainfall and steep terrain,large-scale excavation of mountains and rocks in these construction projects generates a large amount of abandoned slag.This slag not only occupies a large area of land,but also easily causes soil erosion,landslides,debris flows,and other secondary disasters,making the ecological environment extremely fragile.Scientific management is necessary to ensure regional ecological security.Scientific governance must be conducted in dreg fields to ensure the regional ecological security.According to the geological history,climatic conditions,and human-land contradiction in Southwest China,this paper summarizes the research progress of dreg-field ecological restoration technology in the southwest fragile ecological zone.Currently,most slag residue remains as leftover material in four types of construction projects in mountainous areas:roads,hydropower stations,mining,and urban infrastructure engineering.As a systematic project,restoration of dreg fields is usually carried out in accordance with the sequence of"land consolidation-soil reconstruction-vegetation construction-landscape reconstruction-ecological succession".Restoration technologies include soil system and plant community construction technologies.The key to the construction of healthy soil systems lies in slope consolidation and soil conservation,raw soil ripening and soil improvement,and physical,chemical,microbial,and plant measures to repair heavy metal pollution.Plant community establishing techniques are mainly composed of pioneer species selection to stimulate plant establishment,species configuration to promote continuous succession,effective use of soil seed banks,and plant cooperation to promote soil formation.Meanwhile,the main problems in the ecological restoration of dreg fields include unclear orientation of slag restoration,single soil repair technology,and lack of scientific design regarding plant species adaptation,biological invasion,and sustainability of succession in vegetation restoration from an ecological perspective.In future,ecological restoration of dreg fields should be based on the distinction of habitat gradients,biome types,and restoration objectives.Moreover,future restoration technology and management model innovations for dreg field remediation and the optimization of regionally differentiated management strategies in Southwest China are discussed.
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