Little is known about the changes in soil microbial phosphorus (P) cycling potential during terrestrial ecosystem management and restoration, although much research aims to enhance soil P cycling. Here, we used metagenomic sequencing to analyse 18 soil microbial communities at a P-deficient degraded mine site in southern China where ecological restoration was implemented using two soil ameliorants and eight plant species. Our results show that the relative abundances of key genes governing soil microbial P-cycling potential were higher at the restored site than at the unrestored site, indicating enhancement of soil P cycling following restoration. The gcd gene, encoding an enzyme that mediates inorganic P solubilization, was predominant across soil samples and was a major determinant of bioavailable soil P. We reconstructed 39 near-complete bacterial genomes harboring gcd, which represented diverse novel phosphate-solubilizing microbial taxa. Strong correlations were found between the relative abundance of these genomes and bioavailable soil P, suggesting their contributions to the enhancement of soil P cycling. Moreover, 84 mobile genetic elements were detected in the scaffolds containing gcd in the 39 genomes, providing evidence for the role of phage-related horizontal gene transfer in assisting soil microbes to acquire new metabolic potential related to P cycling.

Predicting the dynamics of community composition and functional attributes responding to environmental changes is an essential goal in community ecology but remains a major challenge, particularly in microbial ecology. Here, by targeting a model system with low species richness, we explore the spatial distribution of taxonomic and functional structure of 40 acid mine drainage (AMD) microbial communities across Southeast China profiled by 16S ribosomal RNA pyrosequencing and a comprehensive microarray (GeoChip). Similar environmentally dependent patterns of dominant microbial lineages and key functional genes were observed regardless of the large-scale geographical isolation. Functional and phylogenetic β-diversities were significantly correlated, whereas functional metabolic potentials were strongly influenced by environmental conditions and community taxonomic structure. Using advanced modeling approaches based on artificial neural networks, we successfully predicted the taxonomic and functional dynamics with significantly higher prediction accuracies of metabolic potentials (average Bray–Curtis similarity 87.8) as compared with relative microbial abundances (similarity 66.8), implying that natural AMD microbial assemblages may be better predicted at the functional genes level rather than at taxonomic level. Furthermore, relative metabolic potentials of genes involved in many key ecological functions (for example, nitrogen and phosphate utilization, metals resistance and stress response) were extrapolated to increase under more acidic and metal-rich conditions, indicating a critical strategy of stress adaptation in these extraordinary communities. Collectively, our findings indicate that natural selection rather than geographic distance has a more crucial role in shaping the taxonomic and functional patterns of AMD microbial community that readily predicted by modeling methods and suggest that the model-based approach is essential to better understand natural acidophilic microbial communities.

Elton's biotic resistance hypothesis, which posits that diverse communities should be more resistant to biological invasions, has received considerable experimental support. However, it remains unclear whether such a negative diversity–invasibility relationship would persist under anthropogenic environmental change. By using the common ragweed (Ambrosia artemisiifolia) as a model invader, our 4‐year grassland experiment demonstrated consistently negative relationships between resident species diversity and community invasibility, irrespective of nitrogen addition, a result further supported by a meta‐analysis. Importantly, our experiment showed that plant diversity consistently resisted invasion simultaneously through increased resident biomass, increased trait dissimilarity among residents, and increased community‐weighted means of resource‐conservative traits that strongly resist invasion, pointing to the importance of both trait complementarity and sampling effects for invasion resistance even under resource enrichment. Our study provides unique evidence that considering species’ functional traits can help further our understanding of biotic resistance to biological invasions in a changing environment.

Despite a rich history of theoretical and empirical work showing that increasing biodiversity results in higher ecosystem function, this research has not made a commensurate impact on the reclamation of degraded lands, where enhancing ecosystem function is of primary importance. In this study, we manipulated plant diversity on heavily degraded mine lands and showed that increasing plant diversity greatly enhanced the reclamation of these lands. We found that high‐diversity assemblages were often associated with more biomass, higher stability and less toxic foliage than low diversity treatments, although the monocultures of Miscanthus sinensis (the most productive species) performed equally well as some of the polycultures. Our results showed that species composition and richness explained most of the total variation in biomass yield of the experimental plots, indicating that both the selection and complementarity effects influenced the positive diversity effects observed in this study. Miscanthus sinensis and legumes (as a functional group) were found to be the main contributors to the selection effect. The plots with M. sinensis tended to harbour fewer soil fungal pathogens than those without it and a similar pattern was observed for the legumes, indicating a poorly known plant–soil fungal pathogen feedback for these plants. This kind of feedback appeared to play an important role also in shaping the positive plant species richness–ecosystem function relationships recorded in the degraded mine land. More importantly, we provide the first evidence that the observed plant–soil fungal pathogen feedbacks were likely mediated by chitinolytic bacteria that release anti‐fungal enzymes. Cellulose‐degrading bacteria that aid in plant decomposition and nutrient cycling also attained higher abundances in plots with higher plant diversity, suggesting the contribution of another kind of plant–soil feedback to the positive diversity effects. Synthesis and applications. Our findings reveal that highly diverse plant assemblages are better able to spur plant–soil feedbacks and that increasing plant diversity is an important strategy to enhance land reclamation efficiency after contamination. Meanwhile, our results also indicate that some plants such as Miscanthus sinensis and legumes should be preferentially used to establish diverse plant communities for rapid reclamation of degraded lands.