Fig. 2: Warming enhanced the priming effect and restructured active bacterial communities.

a Response ratios of relative abundances of DOM between warming and control samples in 2016 (Warming vs. Control). Red symbols indicate significantly positive response ratios, while blue symbols indicate significantly negative response ratios. Grey symbols represent non-significant response ratios. Each symbol represents the average ± 95% CI of four biological replicates (n = 4) of warmed or control samples. Significance is denoted as follows: *p ≤ 0.05 and **p ≤ 0.01, as determined by using the one-sided Response Ratio test¹¹⁰. No adjustments were made for multiple comparisons, and exact p-values are provided in the Source Data file. b The overall microbial respiration or priming effect during the 7-day incubation with ¹³C-labeled straw. The bars represent the average ± standard error of four biological replicates (n = 4) of warmed (red) or control (blue) samples. Significance is denoted as follows: **p ≤ 0.01 and ***p ≤ 0.001 determined by using one-sided permutation ANOVA. Exact p-values are provided in the Source Data file. c Abundance of active and total bacterial community after the 7-day incubation with plant litter. The bars represent the average ± standard error of four biological replicates (n = 4) of warmed (red) or control (blue) samples. Significance is denoted as follows: ***p ≤ 0.001, determined by using one-sided permutation ANOVA. Exact p-values are provided in the Source Data file. d The maximum-likelihood phylogenetic tree of active bacterial ASVs (decomposers) across all samples. The phyla colors are defined as follows: Firmicutes (taupe brown), Gammarproteobacteria (lavender purple), Betaproteobacteria (pastel pink), Alphaproteobacteria (light orange), Actinobacteria (dusty pink), Bacteroidetes (eggplant purple), Unclassified (light khaki), Thaumarchaeota (lime green). W: warmed samples; C: control samples; rrn: 16S rRNA gene. e PCoA analysis based on Bray-Curtis dissimilarity metric showing that taxonomic composition of active bacterial communities are different between warmed (red) and control (blue) samples. f Yearly means of relative abundance of active bacterial ASVs in in situ warmed samples during 2010–2016. The least-squares mean values were determined by the linear mixed-effects model. Each bar represents the mean ± standard error of 28 biological replicates (n = 28) of in situ warmed (red) or control (blue) samples over yearly repeated measures during 2010–2016. Significance is denoted as follows: ^#p ≤ 0.1; *p ≤ 0.05; **p ≤ 0.01; and ***p ≤ 0.001, determined by using two-sided ANOVA. No adjustments were made for multiple comparisons, and exact p-values are provided in the Source Data file. Source data are provided as a Source Data file.