Precipitation is one of the most important factors that determine productivity of terrestrial ecosystems. Precipitation across the globe is predicted to change more intensively under future climate change scenarios, but the resulting impact on plant roots remains unclear.Based on 154 observations from experiments in which precipitation was manipulated in the field and root biomass was measured, we investigated responses in fine-root biomass of herbaceous and woody plants to alterations in precipitation.We found that root biomass of herbaceous and woody plants responded differently to precipitation change. In particular, precipitation increase consistently enhanced fine-root biomass of woody plants but had variable effects on herb roots in arid and semi-arid ecosystems. In contrast, precipitation decrease reduced root biomass of herbaceous plants but not woody plants. In addition, with precipitation alteration, the magnitude of root responses was greater in dry areas than in wet areas.Together, these results indicate that herbaceous and woody plants have different rooting strategies to cope with altered precipitation regimes, particularly in water-limited ecosystems. These findings suggest that root responses to precipitation change may critically influence root productivity and soil carbon dynamics under future climate change scenarios.

1. Global change factors may shift community functional composition by driving species turnover (species occurrence and species relative abundance) and intraspecific trait variability. However, their relative contribution in determining the functional response of community to global change, especially nitrogen enrichment and warming, remains unclear.2. We conducted a fully factorial field experiment in a Tibetan alpine meadow to examine the responses of plant community functional composition to nitrogen enrichment and warming by quantifying seven plant functional traits in each plot. Using the sum of squares decomposition, we further disentangled the relative contribution of intraspecific trait variability and species turnover to changes in community functional composition.3. We found that nitrogen enrichment caused a shift of plant community towards a more resource-acquisitive strategy, while warming resulted in a shift towards a more resource-conservative strategy. Plant intraspecific trait variability controls shifts in community functional composition in response to nitrogen enrichment, whereas species turnover (especially change in species relative abundance) mainly explains warming-induced shifts. Nitrogen enrichment and warming did not show significant interactive effects on plant functional composition.4. These findings suggest that nitrogen enrichment and warming can alter community functional composition of alpine meadow through distinct mechanisms.Plant intraspecific trait variability confers functional resilience of Tibetan alpine meadows under nitrogen enrichment, but warming could induce significant turnover of species that pronouncedly impacts community functioning in this highland ecosystem.

No abstract

No abstract

Plant–soil biota interactions play a crucial role in the assembly of plant communities and the maintenance of plant species diversity. However, few studies have tested how the effect of soil biota on plant species and communities depends on environmental context and whether shifts in plant community composition caused by environmental change are associated with variation in plant–soil biota interactions. We combined a field experiment in a Tibetan alpine meadow and a greenhouse experiment with factorial combinations of nitrogen (N) enrichment and warming to examine the role of plant–soil biota interactions in plant community dynamics. The results showed that plant relative abundances were negatively correlated with the net effects of soil biota on plant growth but only under ambient field conditions. Warming and N enrichment alleviated the negative soil biota effects in the greenhouse, and changed plant community composition and reduced species diversity in the field. Importantly, changes in soil biota effects on plant growth were positively correlated with changes in plant relative abundances caused by warming and N enrichment in field. In a parallel field experiment, the diversity of mycorrhizal fungi increased while the diversity of fungal pathogens remained unchanged under warming and N enrichment, indicating that soil biodiversity may play a critical role in plant responses to environmental change. This study empirically demonstrates that altered plant–soil biota interactions explain shifts in plant community composition under global change, providing new insights into the mechanisms of diversity loss in a changing world. A free Plain Language Summary can be found within the Supporting Information of this article.