High nitrogen deposition alters the decomposition of bog plant litter and reduces carbon accumulation |
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Authors: | Luca Bragazza Alexandre Buttler Jonathan Habermacher Lisa Brancaleoni Renato Gerdol Hannu Fritze Peter Hanajík Raija Laiho David Johnson |
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Institution: | 1. WSL Swiss Federal Institute for Forest, Snow and Landscape Research, , CH‐1015 Lausanne, Switzerland;2. école Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), , CH‐1015 Lausanne, Switzerland;3. Department of Biology and Evolution, University of Ferrara, , I‐44121 Ferrara, Italy;4. Finnish Forest Research Institute, , PO Box 18 01301 Vantaa, Finland;5. Department of Soil Science, Comenius University, Faculty of Natural Sciences, , 842 15 Bratislava 4, Slovakia;6. Department of Forest Sciences, University of Helsinki, Peatland Ecology Group, , PO Box 27 0014 Helsinki, Finland;7. University of Aberdeen, Institute of Biological and Environmental Sciences, , Aberdeen, UK |
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Abstract: | 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. |
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Keywords: | decomposition litter accumulation modelling microbial diversity peatland primary production soil enzymatic activity
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phagnum
vascular plants |
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