Morphological constraints on plant‐mediated methane release and oxidation under experimental warming in a peatland and meadow on the Qinghai‐Tibetan Plateau

Alpine meadows and peatlands on the Qinghai-Tibetan Plateau, respectively, act as sinks and sources of atmospheric CH4. Yet, little is known about plant-mediated CH4 fluxes in these ecosystems. We measured CH4 flux from shoots of plants in both ecosystems (45 and 7 species, respectively) and investigated its response to experimental warming. We further investigated the CH4 transport mechanism of key plant species in the peatland through shading and clipping experiments and scanning electron microscope analysis. In the meadow, most plant families showed negative plant CH4 flux (CH4 uptake), ranging from −0.0005 to −0.04 mg CH4 g−1 g h−1. The plant CH4 flux in the peatland was positive for all species but showed large between-species variation, ranging from 0.0006 to 0.167 mg CH4 g−1 g h−1. Experimental warming did not affect plant CH4 flux in the peatland, while it negatively affected CH4 uptake in the meadow. Plant CH4 transport mechanisms in the peatland were species-specific: the dense exodermes of the primary roots restrained transport in Blysmus sinocompressus and Carex myosuroides, while leaves controlled transport in Carex muliensis due to small aerenchyma and limited connectivity. Our findings have important implications for the regional CH4 budget and show that species-level differences should be considered when assessing plant-mediated CH4 emissions.