An evaluation of the sufficiency of natural soil seed banks to support vegetation restoration following severe soil degradation and heavy metal contamination

Abstract

Background and aims

Soil seed banks facilitate vegetation succession and affect the processes involved in restoring degraded land. This study investigated the dynamic characteristics of natural soil seed banks in abandoned mining areas, as well as the abiotic factors influencing seedling emergence and plant growth during ecological restoration.

Methods

We collected soil samples from various layers in mining areas abandoned for 2, 7.5, 15, and > 20 years. Seedling emergence was monitored to determine the viable seed density and species composition of seed banks at different succession states. We also measured soil physicochemical properties and evaluated heavy metal resistance among different plant.

Results

Transient seed banks had a higher seed density than persistent seed banks, and the similarity in species composition between persistent seed banks and aboveground vegetation gradually increased with succession time. There was no difference in plant metal resistance or life form from more than 20 years after recovery, while the reverse was true before this state. Soil TN, water content and pH influenced the species composition of soil seed banks, whereas soil metal concentrations had little effect.

Conclusion

Since the similarity between above-ground vegetation and soil seed banks is low, and plant characteristics show no significant differences in later succession, we suggest that seeding and improving soil conditions are advisable in the early succession, whereas seeding is unnecessary in the late succession. These findings deepen our understanding of the contributions of natural soil seed banks to ecological restoration and provide reference data for developing related management strategies.