Fig. 2: CH4 emission flux from thermokarst lakes during ice-melting and ice-free periods on the Tibetan Plateau.
a Density distribution of CH4 release flux from water storage and ice bubble storage during ice-melting period. The lines indicate CH4 fluxes of individual sampling points from water storage and ice bubble storage. b Total CH4 flux from thermokarst lakes during ice-melting under the vegetation types of alpine swamp meadow (ASM), alpine meadow (AM), alpine steppe (AS) and alpine desert (AD). The violin plot illustrates the magnitude and distribution density of CH4 fluxes of individual samples, in which the boxes represent the 25th and 75th percentiles; the black line indicates the median value, and the black diamond represents the mean value. c Density distribution of CH4 release flux in diffusion and ebullition ways during ice-free period. The lines indicate CH4 fluxes of individual sampling points from ebullition and diffusion. d Total CH4 flux from thermokarst lakes during ice-free period with vegetation types. e The proportions of annual CH4 release in the ways of water storage, ice bubble, ebullition and diffusion for the whole year under different vegetation types on the Plateau. The number at centers of the circle indicates the annual CH4 emissions from thermokarst lakes (Gg C yr−1). One-way analysis of variance (ANOVA) with Tukey’s HSD post hoc comparisons are used to test differences in concentrations across different vegetation types and periods at a significance level of P < 0.05.
