采煤沉陷生态修复工程近地表特性

[Objective]Coal mining subsidence has a bad impact on the ecological and environmental problems in the mining area,and the quality of life and production of the neighboring people has seriously declined,and the problems of resource development and environmental protection,as well as the problems of land for construction and land for industry and mining,have become one of the prominent contradictions in the socio-economic development of the mining area.In response to the national policy of building green mines,a series of coal mining subsidence ecological restoration projects have been launched one after another,to clarify the impact of coal mining surface collapse on the ecological restoration projects in mining areas,to explore the renewal and rejuvenation techniques of ecological forest degradation in subsidence areas suitable for local conditions,and to provide theoretical basis and scientific means for the restoration of vegetation cover in the wind and sand mining subsidence areas and conservation of declining forests.[Method]Using comparative analysis and spatiotemporal intergenerational method,we investigated the understory vegetation in the implementation of the coal mining subsidence ecological restoration project in Yijinholo Banner,Ordos City,in terms of the vegetation configuration pattern(5a Populus simonii,20a Populus simonii,20a Salix psammophila,20a Artemisia desertorum,20a Populus simonii + Salix psammophila,20a Salix psammophila + Artemisia desertorum,2a Hedysarum laeve),and 2 project years(2,5 and 20a),to study the change characteristics of understory vegetation characteristics,surface biological crust,deadfall accumulation and water content,soil temperature,humidity,and soil nutrients during the implementation of the ecological restoration project of coal mining subsidence in YijinhuoLuo Banner of Ordos City.[Result]The results showed that the tree-irrigation hybrid(Populus simonii + Salix psammophila),tree(Populus simonii pure forest)and shrub(Salix psammophila pure forest)types with a project period of 20a were more conducive to increasing the diversity of understory vegetation than the shrub-irrigation hybrid(Salix psammophila + Artemisia desertorum),half-shrub(Artemisia desertorum),and herbaceous(2a Hedysarum laeve)types,and that the above-ground biomass,litter,below-ground biomass,soil organic matter,and the content of total nitrogen and phosphorus of the understory vegetation in the Populus simonii + Salix psammophila tree-irrigation type was significantly higher than that in the other six types of sample sites.The biological crust of the Populus simonii + Salix psammophila was the best developed in terms of cover and thickness,followed by the 20a Populus simonii stand,and no crust in the Populus simonii and Artemisia desertorum sample.The understory vegetation diversity,litter volume(increased by 59.78%),litter natural water content(increased by 56.53%),soil temperature(increased by 3.97%),organic matter(increased by 24.81%),and total nitrogen(increased by 21.44%)contents of the poplar woodland showed an increasing trend with the extension of years,while the soil total phosphorus(decreased by 13.00%),and the water content(decreased by 3.13%)showed a decreasing trend.[Conclusion]Among the different configuration modes,the Populus simonii + Salix psammophila tree-irrigation type sample plot has the best comprehensive performance of various indicators,and with the extension of the project period,it has a stronger role in promoting the ecological restoration of the coal mining subsidence area,vegetation succession,the enhancement of the productivity of the vegetation,and the improvement of the soil fertility in the mining area,and so on.It is suggested that the Populus simonii + Salix psammophila arbor-irrigation type model should be promoted in the ecological restoration project of coal mining subsidence in this region,to achieve better ecological benefits for the construction of vegetation in coal mining subsidence areas.