Carbon–nitrogen interactions in European forests and semi-natural vegetation – Part 2: Untangling climatic, edaphic, management and nitrogen deposition effects on carbon sequestration potentials

Biogeosciences Discussions

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Flechard, Chris R.¹  Montagnani, Leonardo²  Varlagin, Andrej⁴  Loustau, Denis⁵  Legout, Arnaud¹  Ziemblińska, Klaudia⁶  Aubinet, Marc⁷  Aurela, Mika⁸  Chojnicki, Bogdan H.⁹  Drewer, Julia^1,10  Eugster, Werner^1,11  van Oijen, Marcel^1,10  Francez, André-Jean^1,12  Juszczak, Radosław⁹  Kitzler, Barbara^1,13  Kutsch, Werner L.^1,14  Lohila, Annalea^1,15  Longdoz, Bernard^1,16  Matteucci, Giorgio^1,17  Moreaux, Virginie⁵  Neftel, Albrecht^1,19  Olejnik, Janusz⁶  Cameron, David R.^1,10  Sanz, Maria J.^2,21  Siemens, Jan^2,22  Vesala, Timo^1,15  Vincke, Caroline^2,24  Nemitz, Eiko^1,10  Zechmeister-Boltenstern, Sophie^2,25  Butterbach-Bahl, Klaus^2,26  Skiba, Ute M.^1,10  Sutton, Mark A.^1,10  de Vries, Wim^2,27  Ibrom, Andreas^2,28  Buchmann, Nina^1,11  Dise, Nancy B.^1,10  Janssens, Ivan A.^2,29  Neirynck, Johan^3,30 

[1] Institut National de la Recherche en Agriculture;Forest Services;Faculty of Science and Technology, Free University of Bolzano, Piazza Università 5;A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences;Bordeaux Sciences Agro, Institut National de la Recherche en Agriculture;Department of Meteorology, Poznań University of Life Sciences;TERRA Teaching and Research Centre, University of Liège;Finnish Meteorological Institute, Climate System Research;Laboratory of Bioclimatology, Department of Ecology and Environmental Protection, Poznań University of Life Sciences;UK Centre for Ecology and Hydrology (UK CEH);Department of Environmental Systems Science, Institute of Agricultural Sciences, Universitatstr. 2;University of Rennes, Campus de Beaulieu;Federal Research and Training Centre for Forests;Integrated Carbon Observation System (ICOS ERIC) Head Office;Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, 00014 University of Helsinki;Gembloux Agro-Bio Tech, Axe Echanges Ecosystèmes Atmosphère;National Research Council of Italy, Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM);Institute for Geosciences and Environmental research (IGE), Université Grenoble Alpes, Grenoble Institute of Technology;NRE;Department of Matter and Energy Fluxes, Global Change Research Centre;Ikerbasque Foundation and Basque Centre for Climate Change, Scientific Campus of the University of the Basque Country;Institute of Soil Science and Soil Conservation, iFZ Research Centre for Biosystems, Justus Liebig University Giessen;Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, 00014 University of Helsinki;Earth and Life Institute (Environmental sciences), Université catholique de Louvain;Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna;Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU);Wageningen University and Research, Environmental Systems Analysis Group;Department of Environmental Engineering, Technical University of Denmark;Centre of Excellence PLECO (Plant and Vegetation Ecology), Department of Biology, University of Antwerp;Research Institute for Nature and Forest (INBO)

DOI  :  10.5194/bg-17-1621-2020

学科分类：生物科学（综合）

来源: Copernicus Publications

【 摘 要 】

The effects of atmospheric nitrogen deposition ( N dep ) on carbon (C) sequestration in forests have often been assessed by relating differences in productivity to spatial variations of N dep across a large geographic domain. These correlations generally suffer from covariation of other confounding variables related to climate and other growth-limiting factors, as well as large uncertainties in total (dry  +  wet) reactive nitrogen ( N r ) deposition. We propose a methodology for untangling the effects of N dep from those of meteorological variables, soil water retention capacity and stand age, using a mechanistic forest growth model in combination with eddy covariance CO 2 exchange fluxes from a Europe-wide network of 22 forest flux towers. Total N r deposition rates were estimated from local measurements as far as possible. The forest data were compared with data from natural or semi-natural, non-woody vegetation sites. The response of forest net ecosystem productivity to nitrogen deposition ( dNEP ∕ d N dep ) was estimated after accounting for the effects on gross primary productivity (GPP) of the co-correlates by means of a meta-modelling standardization procedure, which resulted in a reduction by a factor of about 2 of the uncorrected, apparent dGPP ∕ d N dep value. This model-enhanced analysis of the C and N dep flux observations at the scale of the European network suggests a mean overall dNEP ∕ d N dep response of forest lifetime C sequestration to N dep of the order of 40–50 g C per g N, which is slightly larger but not significantly different from the range of estimates published in the most recent reviews. Importantly, patterns of gross primary and net ecosystem productivity versus N dep were non-linear, with no further growth responses at high N dep levels ( N dep   >  2.5–3 g N m −2  yr −1 ) but accompanied by increasingly large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high N dep levels implies that the forecast increased N r emissions and increased N dep levels in large areas of Asia may not positively impact the continent's forest CO 2 sink. The large level of unexplained variability in observed carbon sequestration efficiency (CSE) across sites further adds to the uncertainty in the dC∕dN response.

【 授权许可】

CC BY