Anthropogenic climate change has emerged as a critical environmental problem, prompting frequent investigations into its consequences for various ecological systems. Few studies, however, have explored the effect of climate change on ecological stability and the underlying mechanisms. We conduct a field experiment to assess the influence of warming and altered precipitation on the temporal stability of plant community biomass in an alpine grassland located on the Tibetan Plateau. We find that whereas precipitation alteration does not influence biomass temporal stability, warming lowers stability through reducing the degree of species asynchrony. Importantly, biomass temporal stability is not influenced by plant species diversity, but is largely determined by the temporal stability of dominant species and asynchronous population dynamics among the coexisting species. Our findings suggest that ongoing and future climate change may alter stability properties of ecological communities, potentially hindering their ability to provide ecosystem services for humanity.

Satellite data indicate significant advancement in alpine spring phenology over decades of climate warming, but corresponding field evidence is scarce. It is also unknown whether this advancement results from an earlier shift of phenological events, or enhancement of plant growth under unchanged phenological pattern. By analyzing a 35‐year dataset of seasonal biomass dynamics of a Tibetan alpine grassland, we show that climate change promoted both earlier phenology and faster growth, without changing annual biomass production. Biomass production increased in spring due to a warming‐induced earlier onset of plant growth, but decreased in autumn due mainly to increased water stress. Plants grew faster but the fast‐growing period shortened during the mid‐growing season. These findings provide the first in situ evidence of long‐term changes in growth patterns in alpine grassland plant communities, and suggest that earlier phenology and faster growth will jointly contribute to plant growth in a warming climate.

1. As the key carbon (C) fluxes between biosphere and atmosphere, soil respiration (R s ) and ecosystem respiration (R e ) play vital roles in regulating global C balance and climate-biosphere feedback in the Earth system. Despite the fact that numerous manipulative studies and a few meta-analyses have been conducted to examine the responses of R s and its components (i.e. autotrophic [R a ] and heterotrophic respiration [R h ]) as well as R e to grazing (G) or global change factors, the interactive effects between grazing and global change factors remain poorly understood. 2. Here, we performed a comprehensive meta-analysis of manipulative experiments with both grazing and global change factors to quantify their individual and interactive effects on R s and its components as well as R e .3. Our results showed that grazing and drought significantly decreased R s by 12.35% and 20.95%, respectively, whereas warming (W), nitrogen addition (N) and increased precipitation (P) stimulated it by 2.12%, 5.49% and 13.44%, respectively.Similarly, grazing, warming, nitrogen addition and increased precipitation increased R e by 7.21%, 4.94%, 48.45% and 21.57%, respectively, while drought decreased it by 16.86%. However, the combinations of grazing with warming (GW), nitrogen addition (GN) and increased precipitation (GP) exhibited non-significant effects on R s . More importantly, additive interactions between grazing and global change factors exhibited a substantial predominance on R s , R a , R h and R e rather than synergistic and antagonistic ones. 4. Synthesis and applications. Our findings highlight the crucial importance of the interactive effects between grazing and global change factors on soil respiration (R s ) and ecosystem respiration (R e ). Therefore, incorporating this key influence on ecosystem processes into Earth system models (ESMs) could better improve the prediction of climate-biosphere feedbacks and develop sustainable strategies for grassland management in the Anthropocene. K E Y W O R D Sadditive effect, drought, grazing, increased precipitation, meta-analysis, nitrogen addition, warming

Summary Evolutionary history shapes the interspecific relatedness and intraspecific variation, which has a profound influence on plant functional traits and productivity. However, it is far from clear how the phylogenetic relatedness among species and intraspecific variation could contribute to the observed variance in plant biomass responses to climate warming. We compiled a dataset with 284 species from warming experiments to explore the relative importance of phylogenetic, intraspecific, experimental and ecological factors to warming effects on plant biomass, using phylogenetic eigenvector regression and variance decomposition. Our results showed that phylogenetic relatedness could account for about half the total variance in biomass responses to warming, which were correlated with leaf economic traits at the family level but not at species level. The intraspecific variation contributed to approximately one‐third of the variance, whereas the experimental design and ecological characteristics only explained 7–17%. These results suggest that intrinsic factors (evolutionary history) play more important roles than extrinsic factors (experimental treatment and environment) in determining the responses of plant biomass to warming at the global scale. This highlights the urgent need for land surface models to include evolutionary aspects in predicting ecosystem functions under climate change.

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