Rising atmospheric CO₂ reduces nitrogen availability in boreal forests.

ABSTRACT: Anthropogenic nitrogen (N) pollution is a cause of eutrophication globally¹. However, recent datasets indicate that some ecosystems may be experiencing widespread oligotrophication-declining N availability-which is suggested to be a response to elevated atmospheric carbon dioxide (CO₂)². Plant N isotope (δ¹⁵N) chronologies have served as primary evidence for oligotrophication, but there is wide disagreement whether rising CO₂ or temporal changes in N deposition explain these patterns^3-6. Here we construct δ¹⁵N tree-ring chronologies using archived samples from Sweden's 23.5-million-hectare forest area from 1961 to 2018. The study area spans a 1,500-km latitudinal distance where N deposition varies fourfold, but wh

SUBMITTER: Bassett KR 

PROVIDER: S-EPMC12916481 | biostudies-literature | 2026 Feb

REPOSITORIES: biostudies-literature