Long-term nitrogen addition raises the annual carbon sink of a boreal forest to a new steady-state

0561994 - ÚVGZ 2023 RIV NL eng J - Článek v odborném periodiku
Zhao, P. - Chi, J. - Nilsson, M. B. - Lofvenius, M. O. - Hogberg, P. - Jocher, Georg - Lim, H. - Mäkelä, A. - Marshall, J. - Ratcliffe, J. - Tian, X. - Nasholm, T. - Lundmark, T. - Linder, S. - Peichl, M.
Long-term nitrogen addition raises the annual carbon sink of a boreal forest to a new steady-state.
Agricultural and Forest Meteorology. Roč. 324, SEP (2022), č. článku 109112. ISSN 0168-1923. E-ISSN 1873-2240
Institucionální podpora: RVO:86652079
Klíčová slova: Boreal forest * Carbon sequestration * Climate change * Eddy covariance * Forest management * Nitrogen fertilization
Obor OECD: Environmental sciences (social aspects to be 5.7)
Impakt faktor: 6.2, rok: 2022
Způsob publikování: Open access
https://www.sciencedirect.com/science/article/pii/S0168192322002994

The boreal forest is an important global carbon (C) sink. Since low soil nitrogen (N) availability is commonly a key constraint on forest productivity, the prevalent view is that increased N input enhances its C sink-strength. This understanding however relies primarily on observations of increased aboveground tree biomass and soil C stock following N fertilization, whereas empirical data evaluating the effects on the whole ecosystem-scale C balance are lacking. Here we use a unique long-term experiment consisting of paired forest stands with eddy covariance measurements to explore the effect of ecosystem-scale N fertilization on the C balance of a managed boreal pine forest. We find that the annual C uptake (i.e. net ecosystem production, NEP) at the fertilized stand was 16 +/- 2% greater relative to the control stand by the end of the first decade of N addition. Subsequently, the ratio of NEP between the fertilized and control stand remained at a stable level during the following five years with an average NEP to N response of 7 & PLUSMN, 1 g C per g N. Our study reveals that this non-linear response of NEP to long-term N fertilization was the result of a cross-seasonal feedback between the N-induced increases in both growing-season C uptake and subsequent winter C emission. We further find that one decade of N addition altered the sensitivity of ecosystem C fluxes to key environmental drivers resulting in divergent responses to weather patterns. Thus, our study highlights the need to account for ecosystem-scale responses to perturbations to improve our understanding of nitrogen-carbon-climate feedbacks in boreal forests.
Trvalý link: https://hdl.handle.net/11104/0334421