Fig. 4: Changes in species abundance during grassland community shifts in the observations and experiment.

a, Across the 12 observational sites, climatic niche centroids for species with a significant increase in abundance over time (open green circles), with a significant decrease in abundance over time (open orange circles), established (filled green circles), extirpated (filled orange circles) and all other species (open grey circles) (two-sided t-test, P ≤ 0.05). The circle size is proportional to the species’ relative abundance in the community. b, In phase 3 of the experiment, climatic niches for species with increases (green), decreases (orange) and no change in abundance (grey) (two-sided t-test, P ≤ 0.05). c, Across the observations, the summary of climatic niches for species with an increase (n = 94), a decrease (n = 103) and no change (n = 690) in abundance over time. Box plots show the median (centre), the first and third quartiles (bounds of the box), the range extending to the smallest and largest values within 1.5 times the interquartile range from the first and third quartiles (whiskers), and outliers beyond this range (points). The levels of significance and P values are from two-sided Wilcoxon tests for pairwise comparisons (NS: P > 0.05, *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001). d, In the experiment, the summary of climatic niches for species with an increase (n = 15), a decrease (n = 37) and no change (n = 495) in abundance between ambient and warming plots. Descriptions for the box plots and statistics follow c.