Plant community development in a coal mining subsidence area: active versus passive revegetation

Vegetation restoration is a fundamental method of ecological reconstruction in disturbed areas, and revegetation can be achieved by passive (spontaneous succession) and active (human-induced) approaches. Plant community composition, productivity, and diversity were studied in coal mining subsidence areas after 0–15 years of restoration with active (AR) and passive (PR) revegetation approaches in a semiarid region. Moreover, plant community composition, succession, and their relationships with soil variables were analyzed. The results showed that both PR and AR contributed to the recovery of the plant community in terms of plant cover, density, biomass, and diversity, with AR accelerating the recovery of the plant comm unity to a greater extent than PR. Soil moisture and organic matter had close relationships with the plant community variables. The plant communities in PR sites had the same species composition as those in non-subsidence (NS) areas, which led to a more natural plant community in PR than AR sites. Plant community structure in AR sites was altered by the introduced shrubs, with mesophytes developing under the introduced shrubs. These changes produced a different successional trajectory in AR sites from that in NS sites; thus, environmental fluctuations may easily change AR community stability in semiarid environments.