Key role of moss in supplementing nitrogen for plant growth under warming in a permafrost ecosystem.
Zhou W, Bai Y, Xie Y, Wei B, Wanek W
Summary
8.4/10Under climate warming on the Tibetan Plateau, moss-driven nitrogen fixation becomes the only soil process keeping pace with plants' growing nitrogen demands in thawing permafrost—a critical adaptation that may allow vegetation to continue growing despite warming-driven nitrogen stress.
Key Findings
Plant nitrogen demand increased significantly after 2 years of experimental warming, while plants' ability to recycle nitrogen from leaves remained unchanged, forcing greater reliance on soil supplies
Moss-associated biological nitrogen fixation was the only quantified nitrogen supply process that responded positively to warming across both experimental years
Warming altered moss functional traits—expanding suitable colonization areas and increasing carbon availability for nitrogen-fixing microorganisms, driving broader taxonomic diversity
Original Abstract
Enhanced plant productivity under climate warming may partially offset soil carbon losses in cold ecosystems, but this compensation depends on whether soil nitrogen (N) supply can keep pace with the increased N demand associated with accelerated plant growth. However, it remains unclear whether existing soil N supply processes are sufficient to support this rising plant N demand. Based on a unique whole-ecosystem warming experiment in the permafrost region on the Tibetan Plateau, we assess 43 variables encompassing plant N demand and soil N supply. After 2 y of warming, plant N demand significantly increases, while leaf N resorption remains unchanged, indicating a heightened reliance on external soil N inputs. Among all quantified N-supply processes, moss-associated biological N fixation is the only process that responds positively to warming, providing partial compensation for the elevated plant N demand over the two experimental years. This enhancement is associated with warming-driven changes in moss functional traits that likely expand colonization niches and increase carbon availability for diazotrophs, coupled with a warming-induced increase in the breadth and intensity of taxon-level