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

Abstract Alpine meadows and peatlands on the Qinghai‐Tibetan Plateau, respectively, act as sinks and sources of atmospheric CH 4 . Yet, little is known about plant‐mediated CH 4 fluxes in these ecosystems. We measured CH 4 flux from shoots of plants in both ecosystems (45 and 7 species, respectively) and investigated its response to experimental warming. We further investigated the CH 4 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 CH 4 flux (CH 4 uptake), ranging from −0.0005 to −0.04 mg CH 4 g −1 g h −1 . The plant CH 4 flux in the peatland was positive for all species but showed large between‐species variation, ranging from 0.0006 to 0.167 mg CH 4 g −1 g h −1 . Experimental warming did not affect plant CH 4 flux in the peatland, while it negatively affected CH 4 uptake in the meadow. Plant CH 4 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 CH 4 budget and show that species‐level differences should be considered when assessing plant‐mediated CH 4 emissions. Read the free Plain Language Summary for this article on the Journal blog.