Aboveground plant biomass drove the reclamation-year dependence of soil quality along a 49-year vegetation reclamation chronosequence

Soil quality is critical to maintaining the sustainability of vegetation reclamation. However, its variation and crucial driving factors along long-term reclamation chronosequences in metallic mine wastelands require further exploration.

This study determined the variation in soil quality and its dominant drivers across a 49-year vegetation reclamation chronosequence in a vanadium titanomagnetite tailings reservoir using the minimum data set-soil quality index (MDS-SQI) method by analysing multiple soil physical, chemical, and biological properties and plant biomass.

The results revealed that phosphatase (AP), soil organic carbon (SOC), heavy metal pollution (PLI), clay, and total phosphorous were retained as indicators of the MDS. The SQI values increased significantly during the first 13 years after reclamation (p < 0.01), owing to the elevated AP activities and SOC contents. They then maintained a stable and high level within the following reclamation age, which was attributable to the sluggishly increased AP activities and SOC contents and constantly increased PLI values. The aboveground plant biomass primarily drove the reclamation-age dependence of the SQI by impacting soil (microbial) nutrient turnover.

Our study highlights the necessity of incorporating changes in soil heavy metal pollution into post-reclamation soil quality monitoring in metallic mine wastelands. Moreover, the results imply that aboveground plant biomass can indicate the response of soil quality to long-term vegetation reclamation at sites with a single vegetation composition.