Abstract:The dominant tree species Acacia auriculiformis and Eucalyptus urophylla growing on two abandoned oil shale tailings with different restoration years and their root zone soil were used as objects, the influences of tree species and restoration years on the ecological restoration effect of waste lands were studied. The results showed that the heavy metal pollution coefficient of soil in the southern tailing mine after 31 years of restoration was 8, which was significantly lower than the 12.33 of the north tailing mine after 18 years of restoration, indicating that the current heavy metal pollution degree of soil in the southern tailing mine was lighter. The heavy metal concentration and enrichment coefficient in leaves of A. auriculiformis and E. urophylla in the southern tailing mine were significantly higher than those in the northern tailing mine, and the remediation effect of trees in the southern tailing mine was better than that in the northern tailing mine. In addition to the more manganese enrichment in E. urophylla leaves, A. auriculiformis leaves had higher concentration of carbon, zinc, and cadmium, suggesting that A. auriculiformis planted in oil shale tailing remediation with multiple pollution elements could achieve better ecological effects than E. urophylla. Therefore, both A. auriculiformis and E. urophylla had strong ability to remove heavy metals and other harmful elements from oil shale tailings and improve soil quality, and especially A. auriculiformis showed more advantages than E. urophylla under the coexisted stresses of site poverty and multi-element pollution.
