Despite much recent progress, our understanding of diversity–stability relationships across different study systems remains incomplete. In particular, recent theory clarified that within‐species population stability and among‐species asynchronous population dynamics combine to determine ecosystem temporal stability, but their relative importance in modulating diversity‐ecosystem temporal stability relationships in different ecosystems remains unclear. We addressed this issue with a meta‐analysis of empirical studies of ecosystem and population temporal stability in relation to species diversity across a range of taxa and ecosystems. We show that ecosystem temporal stability tended to increase with species diversity, regardless of study systems. Increasing diversity promoted asynchrony, which, in turn, contributed to increased ecosystem stability. The positive diversity–ecosystem stability relationship persisted even after accounting for the influences of environmental covariates (e.g., precipitation and nutrient input). By contrast, species diversity tended to reduce population temporal stability in terrestrial systems but increase population temporal stability in aquatic systems, suggesting that asynchronous dynamics among species are essential for stabilizing diverse terrestrial ecosystems. We conclude that there is compelling empirical evidence for a general positive relationship between species diversity and ecosystem‐level temporal stability, but the contrasting diversity–population temporal stability relationships between terrestrial and aquatic systems call for more investigations into their underlying mechanisms.

Anthropogenic nutrient enrichment is known to alter the composition and functioning of plant communities. However, how nutrient enrichment influences multiple dimensions of community‐ and ecosystem‐level stability remains poorly understood. Using data from a nitrogen (N) and phosphorus (P) addition experiment in a temperate semi‐arid grassland that experienced a natural drought, we show that N enrichment, not P enrichment, decreased grassland functional and compositional temporal stability, resistance and recovery but increased functional and compositional resilience. Compositional stability and species asynchrony, rather than species diversity, were identified as key determinants of all dimensions of grassland functional stability, except for recovery. Whereas grassland functional recovery was decoupled from compositional recovery, N enrichment altered other dimensions of functional stability primarily through changing their corresponding compositional stability dimensions. Our findings highlight the need to examine ecological stability at the community level for a more mechanistic understanding of ecosystem dynamics in the face of environmental change.

Anthropogenic environmental changes are known to affect the Earth's ecosystems. However, how these changes influence assembly trajectories of the impacted communities remains a largely open question. In this study, we investigated the effect of elevated nitrogen (N) deposition and increased precipitation on plant taxonomic and phylogenetic β‐diversity in a 9‐year field experiment in the temperate semi‐arid steppe of Inner Mongolia, China. We found that both N and water addition significantly increased taxonomic β‐diversity, whereas N, not water, addition significantly increased phylogenetic β‐diversity. After the differences in local species diversity were controlled using null models, the standard effect size of taxonomic β‐diversity still increased with both N and water addition, whereas water, not N, addition, significantly reduced the standard effect size of phylogenetic β‐diversity. The increased phylogenetic convergence observed in the water addition treatment was associated with colonizing species in each water addition plot being more closely related to species in other replicate plots of the same treatment. Species colonization in this treatment was found to be trait‐based, with leaf nitrogen concentration being the key functional trait. Synthesis. Our analyses demonstrate that anthropogenic environmental changes may affect the assembly trajectories of plant communities at both taxonomic and phylogenetic scales. Our results also suggest that while stochastic processes may cause communities to diverge in species composition, deterministic process could still drive communities to converge in phylogenetic community structure.

Plant microbiomes are known to influence host fitness and ecosystem functioning, but mechanisms regulating their structure are poorly understood. Here, we explored the assembly mechanisms of leaf epiphytic and endophytic bacterial communities using a subtropical forest biodiversity experiment. Both epiphytic and endophytic bacterial diversity increased as host tree diversity increased. However, the increased epiphytic diversity in more diverse forests was driven by greater epiphytic diversity (i.e. greater α‐diversity) on individual trees, whereas the increased endophytic diversity in more diverse forests was driven by greater dissimilarity in endophytic composition (i.e. greater β‐diversity) among trees. Mechanistically, responses of epiphytes to changes in host diversity were consistent with mass effects, whereas responses of endophytes were consistent with species sorting. Synthesis. These results provided novel experimental evidence that biodiversity declines of plant species will lead to biodiversity declines of plant‐associated microbiomes, but the underlying mechanism may differ between habitats on the plant host.

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