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High nitrogen deposition alters the decomposition of bog plant litter and reduces carbon accumulation
Author(s) -
Bragazza Luca,
Buttler Alexandre,
Habermacher Jonathan,
Brancaleoni Lisa,
Gerdol Renato,
Fritze Hannu,
Hanajík Peter,
Laiho Raija,
Johnson David
Publication year - 2012
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2011.02585.x
Subject(s) - bog , peat , biogeochemical cycle , litter , nutrient , plant litter , nitrogen , environmental chemistry , deposition (geology) , carbon sink , ecosystem , chemistry , environmental science , botany , ecology , biology , organic chemistry , sediment , paleontology
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.