Background Extensive mining in the Northwest arid desert area has caused serious ecological environment destruction. The ecological restoration of waste dump is very difficult. At present, the ecological restoration modes of waste dump restoration engineering is single and the matching measures are incomplete. Besides there is a shortage of ecological restoration modes which are suitable for the application of different site types in the Northwest arid desert area with well restoration effect. The purpose of this study is to systematically evaluate ecological restoration modes and pick out suitable ecological restoration modes for different site types. Besides we will make suggestions for each mode based on soil carbon storage; soil total nitrogen storage and C/N.

Methods We investigated the vegetation growth status and soil physical and chemical properties of 14 restored waste dumps in Wuhai city. We selected 13 indices from vegetation restoration, soil modification and economic cost to construct evaluation system by the combination of component analysis and entropy weight. The evaluation system was then used to screen suitable ecological restoration modes.

Results 1) The ecological restoration modes that are suitable for different site types consisted of interception and drainage measures and slope protection measures, i.e., gravel capping, Salix pammophila checkerboard, blanket covering, brick square/arch sash, dense mesh covering, ecological bag interception and drainage, dry masonry interception ditch, pipe drainage, and sowing. 2) Blanket covering+ecological bag drainage+sowing mode was suitable for both of medium layer steep shady-sunny slopes; medium layer turned-sharply shady-sunny slopes and medium layer steep shady slopes. 3) The recovery effect of the brick square/arch sash was slightly different, resulting from the difference of layout size and construction quality.

Conculsions 1)The shady slope is more conducive to vegetation restoration, resulting from lower vegetation transpiration and less soil water consumption. 2) Compared with blanket covering mode, brick square/arch sash mode is more beneficial to organic carbon and nitrogen accumulation in the soil and reduce soil erosion. We screened 14 suitable ecological restoration modes for 9 site types from 23 modes which we investigated in the 14 waste dumps.