TY - JOUR

T1 - High nitrogen deposition alters the decomposition of bog plant litter and reduces carbon accumulation

AU - Bragazza, Luca

AU - Buttler, Alexandre

AU - Habermacher, Jonathan

AU - Brancaleoni, Lisa

AU - Gerdol, Renato

AU - Fritze, Hannu

AU - Hanajik, Peter

AU - Laiho, Raija

AU - Johnson, David

PY - 2012/3/31

Y1 - 2012/3/31

N2 - Bogs are globally important sinks of atmospheric carbon (C) due to the accumulation of partially decomposed litter that forms peat. Because bogs receive their nutrients from the atmosphere, the world-wide increase of nitrogen (N) deposition is expected to affect litter decomposition and, ultimately, the rate of C accumulation. However, the mechanism of such biogeochemical alteration remains unclear and quantification of the effect of N addition on litter accumulation has yet to be done. Here, we show that 7 years of N addition to a bog decreased the C : N ratio, increased the bacterial biomass and stimulated the activity of hydrolytic and oxidative enzymes in surface peat. Furthermore, N addition modified nutrient limitation of microbes during litter decomposition so that phosphorus became a primary limiting nutrient. Alteration of N release from decomposing litter affected bog water chemistry and the competitive balance between peat-forming mosses and vascular plants. We estimate that deposition of about 4 g N m−2 yr−1 will cause a mean annual reduction of fresh litter C accumulation of about 40 g m−2 primarily as a consequence of decreased litter production from peat-forming mosses. Our findings show that N deposition interacts with both above and below ground components of biodiversity to threaten the ability of bogs to act as N-sinks, which may offset the positive effects of N on C accumulation seen in other ecosystems.

AB - Bogs are globally important sinks of atmospheric carbon (C) due to the accumulation of partially decomposed litter that forms peat. Because bogs receive their nutrients from the atmosphere, the world-wide increase of nitrogen (N) deposition is expected to affect litter decomposition and, ultimately, the rate of C accumulation. However, the mechanism of such biogeochemical alteration remains unclear and quantification of the effect of N addition on litter accumulation has yet to be done. Here, we show that 7 years of N addition to a bog decreased the C : N ratio, increased the bacterial biomass and stimulated the activity of hydrolytic and oxidative enzymes in surface peat. Furthermore, N addition modified nutrient limitation of microbes during litter decomposition so that phosphorus became a primary limiting nutrient. Alteration of N release from decomposing litter affected bog water chemistry and the competitive balance between peat-forming mosses and vascular plants. We estimate that deposition of about 4 g N m−2 yr−1 will cause a mean annual reduction of fresh litter C accumulation of about 40 g m−2 primarily as a consequence of decreased litter production from peat-forming mosses. Our findings show that N deposition interacts with both above and below ground components of biodiversity to threaten the ability of bogs to act as N-sinks, which may offset the positive effects of N on C accumulation seen in other ecosystems.

KW - decomposition

KW - litter accumulation modelling

KW - microbial diversity

KW - peatland

KW - primary production

KW - soil enzymatic activity

KW - S phagnum

KW - vascular plants

U2 - 10.1111/j.1365-2486.2011.02585.x

DO - 10.1111/j.1365-2486.2011.02585.x

M3 - Journal article

VL - 18

SP - 1163

EP - 1172

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

IS - 3

ER -