Recovery quality index as a tool for monitoring the mined land reclamation

Many ecosystems are being severely degraded, leading the United Nations to deem 2021-2030 as the Decade on Ecosystem Restoration. To be successful, this effort requires robust monitoring tools to assess land reclamation practices. This study aimed to evaluate the quality of recovery efforts in mined areas by developing a Recovery Quality Index (RQI) based on soil and vegetation indicators. Using the heavily mined Iron Quadrangle region of Brazil as an example, four undisturbed reference areas were selected: Atlantic Forest; ferruginous rupestrian grassland with dense vegetation; ferruginous rupestrian grassland with sparse vegetation; and quartzite rupestrian grassland. Four areas directly or indirectly affected by mining were selected, including an environmental compensation area set aside 5 years prior to the study, two sterile piles that had undergone recovery for 15 and 20 years, and a cave area with 15 years of recovery. Two vegetation parameters and 34 soil attributes were used in a Principal Component Analysis (PCA) to select indicators and scores. Vegetative parameters had the lowest RQI weights. Soil physical indicators tended to be the most important. RQI values were lowest when Atlantic Forest was used as the reference, showing that the forest was a unique ecosystem, and the cave site had lower RQI scores than the other restored sites, indicating the high degree of disturbance that occurred in that low-lying area. The oldest sterile pile tended to have higher RQI values than the newest and similar values to the less disturbed compensation areas. The recovery quality index values were similar in all areas, with 5 to 20 years in the recovery process, showing that the rehabilitation process is slow in this environment.