Assessing the naturalness of a restored coal mine area on the Loess Plateau, China

The Loess Plateau in China is an important area for mineral resources and therefore heavily exploited. As a measure to solve the conflict between conservation and development, ecological restoration has attracted more and more attention. More methods are needed to assess their effectiveness in achieving ecological and social goals. To adequately assess the effectiveness of natural restoration, the naturalness index (NI) has been developed to evaluate restoration effectiveness based on the Soil nutrient index (SNI), community composition index (CCI), and community succession index (CSI). By developing and applying of the NI to an open-pit mining area on Loess plateau, northwest China, the results show that: (i) In the study area, the cumulative dominance index of perennial grasses, the community function index, soil organic matter, and soil hydrolysable nitrogen greatly explained the community development. (ii) All the indicators values have changed with the increase of revolution time, the value of SNI increase obviously than the CCI and CSI comparing with the control plot, which indicated that the soil nutrient could be completely restored more easily. (iii) According to the Logistic Growth Model between NI and restoration time, it can be deduced that an ecosystem similar to the original ecosystem could be established after about 29 years of natural restoration.