Changes in forest nitrogen cycling across deposition gradient revealed by δ15N in tree rings. (1st July 2022)

• Record Type: Journal Article
• Authors: Oulehle, Filip; Tahovská, Karolina; Ač, Alexandr; Kolář, Tomáš; Rybníček, Michal; Čermák, Petr; Štěpánek, Petr; Trnka, Miroslav; Urban, Otmar; Hruška, Jakub
• Is Part Of: Environmental pollution. Volume 304(2022)
• Publication Date: 2022-07-01
• Subjects: nitrogen -- Phosphorus -- Isotope -- Eutrophication -- Forest productivity -- Tree species; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.119104
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Tree rings provide valuable insight into past environmental changes. This study aimed to evaluate perturbations in tree ring width (TRW) and δ 15 N alongside soil acidity and nutrient availability gradients caused by the contrasting legacy of air pollution (nitrogen [N] and sulphur [S] deposition) and tree species (European beech, Silver fir and Norway spruce). We found consistent declines of tree ring δ 15 N, which were temporarily unrelated to the changes in the TRW. The rate of δ 15 N change in tree rings was related to the contemporary foliar carbon (C) to phosphorus (P) ratio. This observation suggested that the long-term accumulation of 15 N depleted N in tree rings, likely mediated by retained N from deposition, was restricted primarily to stands with currently higher P availability. The shifts observed in tree-ring δ 15 N and TRW suggest that acidic air pollution rather than changes in stand productivity determined alteration of N and C cycles. Stable N isotopes in tree rings provided helpful information on the trajectory of the N cycle over the last century with direct consequences for a better understanding of future interactions among N, P and C cycles in terrestrial ecosystems. Graphical abstract: Image 1 Highlights: Measured 15 N/ 14 N isotope ratio in tree rings extending back to the 19th century. Consistent declines in the tree-ring δ 15 N connected to the legacy of air pollution. Forest productivity unrelated to the observed tree-ring δ 15 N changes. Contemporary foliar C/P defined the trajectory of tree-ring δ 15 N. Future pathways of nitrogen and carbon in forests are likely P availability dependent.