A Study On Revegetating Techniques And Effects In Iron Ore Wastelands In Beijing

The wastelands formed by iron ore mining have caused serious soil erosion and ecosystem degradation in Beijing, which directly impact the production and living conditions of residents around mining areas as well as regional economic sustainable development. So the revegetation on iron ore wastelands is of great significance for the ecological environment requirements of the belt named ecological conservation and development of capital..Through the investigation of terrain, landforms, vegetation, soil and so on in typical representative Shou Yun iron ore in Beijing, the vegetation, soil characteristics and the revegetation ecological effect were analyzed. By using the space-time method the succession dynamics of vegetation restoration was found. The techniques suitable for soil improvement and native plant species matching were study. The main results are as follows:(1) The mine tailing on gentle sunny slope, gravel with little soil on gentle sunny slope and earth-rock on gentle sunny slope can be covered with 10cm soil, planted with right plants and fertilized and the bare rock fissure with regolith on steep sunny slope can be restored accelerated by rational allocating matrix with plant seeds, so as to improve the soil structure and fertility status with different degree. It is necessary to build up soil fertility continuously for consumed soil nutrients with plant growing.(2) The characteristics analysis of mine tailing and gravel with little soil on gentle sunny slope showed that the seeds were less and belonged to the herb. There was great different between the seed bank and the aboveground vegetation.(3) The revegetation composition of different restoration measures of mine tailing mainly includes Gramineae, Leguminosae, and Compositae. The annual and biennial herb has a large proportion. During 20 years of natural restoration for gravel with little soil on gentle slope, the plant community was transformed from shrub-grass community without obvious dominant species to the shrub-grass community dominated by Vitex negundo. The heliophilous and drought tolerant tree population is the dominant species for the 10-year and 20- year plant communities of natural restoration. The 30-year natural restoration community is mainly consisted by shrub community dominated by Vitex negundo. For earth-rock on gentle sunny slope the herb is dominant among the natural settlement plants.(4) There was significant difference of species richness between 1-year artificial restoration and natural plant communities. There was extremely significant difference of species richness between 3-year artificial restoration and natural plant communities. The Simpson diversity index was significant difference between 4-year artificial restoration and natural plant communities. In reference to the plant community of burozem on gentle sunny slope, theβdiversity index of plant community for mine tailing on gentle sunny slope is in the order of 4-year artificial restoration > 3-year artificial restoration > 1-year artificial restoration > 10-year artificial restoration. The 7 species grouping result of 10-year artificial vegetation restoration is: Cosmos bipinnatus and Echinochloa crusgalli are degenerative species group; Astragalus adsurgens is transitional species; Artemisia annua, Setaria viridis, Amorpha fruticosa and Vitex negundo are progressing species group.For gravel with little soil on gentle sunny slope the species richness of natural and artificial vegetation restoration decreased with time, while the other three diversity indexes were increased with time. In reference to the plant community of burozem on gentle sunny slope, theβdiversity index of plant community for gravel with little soil on gentle sunny slope is in the order of: 1-year artificial restoration > 10-year natural restoration >2-year artificial restoration >20-year natural restoration. The 8 species grouping result of 20-year artificial and natural vegetation restoration is: Cosmos bipinnatus , Amaranthus mangostanus and Artemisia scoparia are degenerative species group; Medicago sativa, Echinochloa crusgalli, Setaria viridis and Artemisia sphaerocephala are transitional species; Vitex negundo is progressing species group.For bare rock fissure with regolith on steep sunny slope the a diversity index of natural vegetation restoration fluctuated in process of time. The diversity index of artificial vegetation restoration is apparently higher than that of plant community in burozem on gentle sunny slope. In reference to the plant community of burozem on gentle sunny slope, theβdiversity index of bare rock fissure with regolith on steep sunny slope is in the order of: 10-year natural restoration> 2-year artificial restoration> 20-year natural restoration> 30-year of natural restoration. The 11 species grouping result of 30-year artificial and natural vegetation restoration is: Digitaria sanguinalis , Amaranthus mangostanus, Artemisia sphaerocephala, Setaria viridis and Xanthium sibiricum are degenerative species group; Arteimiaisia sieuersiana and P.cathayana are transitional species; Ailanthus altissima, Artemisia scoparia, Ulmus pumila, Vitex negundo are progressing species group.For earth-rock on gentle sunny slope the a diversity index is apparently higher than that of natural plant community. In reference to the plant community of burozem on gentle sunny slope, theβdiversity index of earth-rock on gentle sunny slope is in the order of: 2-year artificial restoration> 10-year natural restoration > 1-year artificial restoration. The 7 species grouping result of 10-year artificial and natural vegetation restoration is: Setaria viridis and Medicago sativa are degenerative species group; Artemisia sacrorum is transitional species; Vitex negundo, Platycladus orientalis, Chenopodium album and Pinus tabulaeformis are progressing species group.(5) According to the partition result of natural and artificial plant community with TWINSPAN the ecological effects were analyzed. The similarity order between natural restoration communities and natural plant communities is: Ailanthus altissima community> Vitex negundo -Alopecurus pratensis community> Ulmus pumila- Arteimiaisia sieuersiana community > Setaria viridis-Artemisia sphaerocephala community>Amaranthus mangostanus-Chenopodium glaucum community. The soil bulk density and pH value of Amaranthus mangostanus- Chenopodium glaucum community are minimum,The soil organic matter, nitrogen and potassium of Setaria viridis-Artemisia sphaerocephala community are largest.The soil available phosphorus of Ulmus pumila- Arteimiaisia sieuersiana community is largest.The similarity order between artificial restoration community and natural plant community is: Setaria viridis-Ailanthus altissima community>Amorpha fruticosa-Caragana sinica community>Medicago sativa-Robinia pseudoacacia community>Cosmos bipinnatus-Pennisetum alopecuroides community>Astragalus adsurgens community> Lolium perenne-Hemerocallis fulva community.