Articles | Volume 13, issue 18
Research article 19 Sep 2016
Research article | 19 Sep 2016
Autotrophic component of soil respiration is repressed by drought more than the heterotrophic one in dry grasslands
János Balogh et al.
No articles found.
Lutz Merbold, Charlotte Decock, Werner Eugster, Kathrin Fuchs, Benjamin Wolf, Nina Buchmann, and Lukas Hörtnagl
Biogeosciences, 18, 1481–1498,Short summary
Our study investigated the exchange of the three major greenhouse gases (GHGs) over a temperate grassland prior to and after restoration through tillage in central Switzerland. Our results show that irregular management events, such as tillage, have considerable effects on GHG emissions in the year of tillage while leading to enhanced carbon uptake and similar nitrogen losses via nitrous oxide in the years following tillage to those observed prior to tillage.
Yafei Li, Franziska Aemisegger, Andreas Riedl, Nina Buchmann, and Werner Eugster
Hydrol. Earth Syst. Sci. Discuss.,
Revised manuscript accepted for HESSShort summary
Dew and fog inputs are rarely investigated in temperate ecosystems. With climate change, prolonged dry periods are expected, hence dew and fog might become a more important water source even in temperate grasslands to alleviate plant drought stress. Our results using stable water isotopes highlight the importance of dew and fog inputs to temperate grasslands during prolonged dry periods and reveal the complexity of the local water cycle including different pathways of dew and fog inputs.
Mercedes Ibañez, Núria Altimir, Àngela Ribas, Werner Eugster, and Maria-Teresa Sebastià
Manuscript not accepted for further reviewShort summary
Our study unravels the influence of forage species on ecosystem scale CO2 fluxes, and is the first long term dataset of a forage system in the Pyrenees. We found strong evidence that cereal legume mixtures enhanced system's CO2 sink capacity compared to cereal monocultures, by enhancing photosynthesis and voluntary regrowth, decisive for the net CO2 budget. This knowledge is crucial to develop climate change mitigation strategies, while ensuring productivity of forage systems.
Werner Eugster, James Laundre, Jon Eugster, and George W. Kling
Atmos. Meas. Tech., 13, 2681–2695,Short summary
Measuring ambient methane concentrations requires expensive optical sensors. The first electrochemical analyzer that shows a response to ambient levels of methane is now available. We present the first long-term deployment of such sensors in an arctic environment (temperatures from −41 to 27 °C). We present a method based on these measurements to convert the signal to methane concentrations (corrected for the effects of air temperature and relative humidity) and ensure long-term stability.
Stefan Osterwalder, Werner Eugster, Iris Feigenwinter, and Martin Jiskra
Atmos. Meas. Tech., 13, 2057–2074,Short summary
Direct mercury (Hg) flux studies are crucial to improve our understanding of terrestrial Hg cycling and human Hg exposure. We tested a new system to measure Hg fluxes using the eddy covariance technique. Our Eddy Mercury system revealed a net Hg re-emission flux from a grassland. We concluded that the prevailing dry conditions resulted in low uptake of CO2 and Hg. Eddy Mercury has the potential to address some of the largest uncertainties in global Hg cycling through long-term flux measurements.
Chris R. Flechard, Andreas Ibrom, Ute M. Skiba, Wim de Vries, Marcel van Oijen, David R. Cameron, Nancy B. Dise, Janne F. J. Korhonen, Nina Buchmann, Arnaud Legout, David Simpson, Maria J. Sanz, Marc Aubinet, Denis Loustau, Leonardo Montagnani, Johan Neirynck, Ivan A. Janssens, Mari Pihlatie, Ralf Kiese, Jan Siemens, André-Jean Francez, Jürgen Augustin, Andrej Varlagin, Janusz Olejnik, Radosław Juszczak, Mika Aurela, Daniel Berveiller, Bogdan H. Chojnicki, Ulrich Dämmgen, Nicolas Delpierre, Vesna Djuricic, Julia Drewer, Eric Dufrêne, Werner Eugster, Yannick Fauvel, David Fowler, Arnoud Frumau, André Granier, Patrick Gross, Yannick Hamon, Carole Helfter, Arjan Hensen, László Horváth, Barbara Kitzler, Bart Kruijt, Werner L. Kutsch, Raquel Lobo-do-Vale, Annalea Lohila, Bernard Longdoz, Michal V. Marek, Giorgio Matteucci, Marta Mitosinkova, Virginie Moreaux, Albrecht Neftel, Jean-Marc Ourcival, Kim Pilegaard, Gabriel Pita, Francisco Sanz, Jan K. Schjoerring, Maria-Teresa Sebastià, Y. Sim Tang, Hilde Uggerud, Marek Urbaniak, Netty van Dijk, Timo Vesala, Sonja Vidic, Caroline Vincke, Tamás Weidinger, Sophie Zechmeister-Boltenstern, Klaus Butterbach-Bahl, Eiko Nemitz, and Mark A. Sutton
Biogeosciences, 17, 1583–1620,Short summary
Experimental evidence from a network of 40 monitoring sites in Europe suggests that atmospheric nitrogen deposition to forests and other semi-natural vegetation impacts the carbon sequestration rates in ecosystems, as well as the net greenhouse gas balance including other greenhouse gases such as nitrous oxide and methane. Excess nitrogen deposition in polluted areas also leads to other environmental impacts such as nitrogen leaching to groundwater and other pollutant gaseous emissions.
Chris R. Flechard, Marcel van Oijen, David R. Cameron, Wim de Vries, Andreas Ibrom, Nina Buchmann, Nancy B. Dise, Ivan A. Janssens, Johan Neirynck, Leonardo Montagnani, Andrej Varlagin, Denis Loustau, Arnaud Legout, Klaudia Ziemblińska, Marc Aubinet, Mika Aurela, Bogdan H. Chojnicki, Julia Drewer, Werner Eugster, André-Jean Francez, Radosław Juszczak, Barbara Kitzler, Werner L. Kutsch, Annalea Lohila, Bernard Longdoz, Giorgio Matteucci, Virginie Moreaux, Albrecht Neftel, Janusz Olejnik, Maria J. Sanz, Jan Siemens, Timo Vesala, Caroline Vincke, Eiko Nemitz, Sophie Zechmeister-Boltenstern, Klaus Butterbach-Bahl, Ute M. Skiba, and Mark A. Sutton
Biogeosciences, 17, 1621–1654,Short summary
Nitrogen deposition from the atmosphere to unfertilized terrestrial vegetation such as forests can increase carbon dioxide uptake and favour carbon sequestration by ecosystems. However the data from observational networks are difficult to interpret in terms of a carbon-to-nitrogen response, because there are a number of other confounding factors, such as climate, soil physical properties and fertility, and forest age. We propose a model-based method to untangle the different influences.
Kathrin Fuchs, Lukas Hörtnagl, Nina Buchmann, Werner Eugster, Val Snow, and Lutz Merbold
Biogeosciences, 15, 5519–5543,Short summary
Replacing fertiliser nitrogen with biologically fixed nitrogen (BFN) through legumes has been suggested as a strategy for nitrous oxide (N2O) mitigation from intensively managed grasslands. On our site the mitigation strategy reduced N2O emissions by 54 % and 39 % in 2015 and 2016, while annual yields were similar under mitigation management. We conclude that N2O emissions can be effectively reduced without losses in yield by increasing the clover proportion and reducing fertilisation.
Carmen Emmel, Annina Winkler, Lukas Hörtnagl, Andrew Revill, Christof Ammann, Petra D'Odorico, Nina Buchmann, and Werner Eugster
Biogeosciences, 15, 5377–5393,Short summary
It is of great interest to know whether croplands act as a net source or sink of atmospheric CO2 and if soil carbon (C) stocks are preserved over long timescales due to the role of C in soil fertility. For a cropland in Switzerland it was found that managing the field under the Swiss framework of the Proof of Ecological Performance (PEP) resulted in soil C losses of 18.0 %. Additional efforts are needed to bring Swiss management practices closer to the goal of preserving soil C in the long term.
Werner Eugster, Carmen Emmel, Sebastian Wolf, Nina Buchmann, Joseph P. McFadden, and Charles David Whiteman
Atmos. Chem. Phys., 17, 14887–14904,Short summary
The effects of penumbral shading of the solar eclipse of 20 March 2015 on near-surface meteorology across Switzerland (occultation 65.8–70.1 %) was investigated. Temperature effects at 184 weather stations are compared with temperature drops reported in the literature since 1834. A special focus is, however, put on wind direction effects observed at six flux sites (with 20 Hz data) and 165 meteorological stations (with 10 min resolution data). Results show the importance of local topography.
Dóra Hidy, Zoltán Barcza, Hrvoje Marjanović, Maša Zorana Ostrogović Sever, Laura Dobor, Györgyi Gelybó, Nándor Fodor, Krisztina Pintér, Galina Churkina, Steven Running, Peter Thornton, Gianni Bellocchi, László Haszpra, Ferenc Horváth, Andrew Suyker, and Zoltán Nagy
Geosci. Model Dev., 9, 4405–4437,Short summary
This paper provides detailed documentation on the changes implemented in the widely used biogeochemical model Biome-BGC. The version containing all improvements is referred to as Biome-BGCMuSo (Biome-BGC with multilayer soil module). Case studies on forest, cropland, and grassland are presented to demonstrate the effect of developments on the simulation. By using Biome-BGCMuSo, it became possible to analyze the effects of different environmental conditions and human activities on the ecosystems.
Inge Juszak, Werner Eugster, Monique M. P. D. Heijmans, and Gabriela Schaepman-Strub
Biogeosciences, 13, 4049–4064,Short summary
Changes in Arctic vegetation composition and structure feed back to climate and permafrost. Using field observations at a Siberian tundra site, we find that dwarf shrubs absorb more solar radiation than wet sedges and thus amplify surface warming, especially during snow melt. On the other hand, permafrost thaw was enhanced below sedges as a consequence of high soil moisture. Standing dead sedge leaves affected the radiation budget strongly and deserve more scientific attention.
Stephan Henne, Dominik Brunner, Brian Oney, Markus Leuenberger, Werner Eugster, Ines Bamberger, Frank Meinhardt, Martin Steinbacher, and Lukas Emmenegger
Atmos. Chem. Phys., 16, 3683–3710,Short summary
Greenhouse gas emissions can be assessed by "top-down" methods that combine atmospheric observations, a transport model and a mathematical optimisation framework. Here, we apply such a top-down method to the methane emissions of Switzerland, utilising observations from the recently installed CarboCount-CH network. Our Swiss total emissions largely agree with those of the national "bottom-up" inventory, whereas regional differences suggest lower than reported emissions from manure handling.
J. Stieger, I. Bamberger, N. Buchmann, and W. Eugster
Atmos. Chem. Phys., 15, 14055–14069,Short summary
At night, concentrations of methane and other trace gases in the near-surface atmosphere increase due to limited turbulent mixing and confluence of cold air from valley slopes towards the valley bottom. Here we used a tethered balloon sounding system to obtain time-height profiles of methane concentrations from which we compute methane emissions. These flux estimates serve as the first experimental validation of Swiss agricultural methane emissions at the farm scale.
B. Oney, S. Henne, N. Gruber, M. Leuenberger, I. Bamberger, W. Eugster, and D. Brunner
Atmos. Chem. Phys., 15, 11147–11164,Short summary
We present a detailed analysis of a new greenhouse gas measurement network in the Swiss Plateau, situated between the Jura mountains and the Alps. We find the network's measurements to be information rich and suitable for studying surface carbon fluxes of the study region. However, we are limited by the high-resolution (2km) atmospheric transport model's ability to simulate meteorology at the individual measurement stations, especially at those situated in rough terrain.
W. Eugster and L. Merbold
SOIL, 1, 187–205,Short summary
The eddy covariance (EC) method has become increasingly popular in soil science. The basic concept of this method and its use in different types of experimental designs in the field are given, and we indicate where progress in advancing and extending the field of applications is made. The greatest strengths of EC measurements in soil science are (1) their uninterrupted continuous measurement of gas concentrations and fluxes and (2) spatial integration over small-scale heterogeneity in the soil.
H. N. Mbufong, M. Lund, M. Aurela, T. R. Christensen, W. Eugster, T. Friborg, B. U. Hansen, E. R. Humphreys, M. Jackowicz-Korczynski, L. Kutzbach, P. M. Lafleur, W. C. Oechel, F. J. W. Parmentier, D. P. Rasse, A. V. Rocha, T. Sachs, M. K. van der Molen, and M. P. Tamstorf
Biogeosciences, 11, 4897–4912,
R. V. Hiller, D. Bretscher, T. DelSontro, T. Diem, W. Eugster, R. Henneberger, S. Hobi, E. Hodson, D. Imer, M. Kreuzer, T. Künzle, L. Merbold, P. A. Niklaus, B. Rihm, A. Schellenberger, M. H. Schroth, C. J. Schubert, H. Siegrist, J. Stieger, N. Buchmann, and D. Brunner
Biogeosciences, 11, 1941–1959,
S. Zielis, S. Etzold, R. Zweifel, W. Eugster, M. Haeni, and N. Buchmann
Biogeosciences, 11, 1627–1635,
P. Michna, W. Eugster, R. V. Hiller, M. J. Zeeman, and H. Wanner
Geogr. Helv., 68, 249–263,
D. Imer, L. Merbold, W. Eugster, and N. Buchmann
Biogeosciences, 10, 5931–5945,
Related subject area
Biogeochemistry: Stable Isotopes & Other TracersModern silicon dynamics of a small high-latitude subarctic lakeRadium-228-derived ocean mixing and trace element inputs in the South AtlanticNitrogen isotopic fractionations during nitric oxide production in an agricultural soilSilicon uptake and isotope fractionation dynamics by crop speciesBarium stable isotopes as a fingerprint of biological cycling in the Amazon River basinBottomland hardwood forest growth and stress response to hydroclimatic variation: evidence from dendrochronology and tree ring Δ13C valuesN2O isotope approaches for source partitioning of N2O production and estimation of N2O reduction – validation with the 15N gas-flux method in laboratory and field studiesTechnical note: Single-shell δ11B analysis of Cibicidoides wuellerstorfi using femtosecond laser ablation MC-ICPMS and secondary ion mass spectrometrySources and cycling of nitrogen in a New England river discerned from nitrate isotope ratiosBiogeochemical evidence of anaerobic methane oxidation and anaerobic ammonium oxidation in a stratified lake using stable isotopesEvaluating the response of ẟ13C in Haloxylon ammodendron, a dominant C4 species in Asian desert ecosystem, to water and nitrogen addition as well as the availability of its ẟ13C as the indicator of water use-efficiencyEffects of 238U variability and physical transport on water column 234Th downward fluxes in the coastal upwelling system off PeruDo degree and rate of silicate weathering depend on plant productivity?Alpine Holocene tree-ring dataset: age-related trends in the stable isotopes of cellulose show species-specific patternsIdeas and perspectives: The same carbon behaves like different elements – an insight into position-specific isotope distributionsSeasonal dynamics of the COS and CO2 exchange of a managed temperate grasslandLeaf-scale quantification of the effect of photosynthetic gas exchange on Δ17O of atmospheric CO2The stable carbon isotope signature of methane produced by saprotrophic fungiUnderstanding the effects of early degradation on isotopic tracers: implications for sediment source attribution using compound-specific isotope analysis (CSIA)Oxygen isotope composition of waters recorded in carbonates in strong clumped and oxygen isotopic disequilibriumIsotopic evidence for alteration of nitrous oxide emissions and producing pathways' contribution under nitrifying conditionsTrace element composition of size-fractionated suspended particulate matter samples from the Qatari Exclusive Economic Zone of the Arabian Gulf: the role of atmospheric dustBenthic carbon fixation and cycling in diffuse hydrothermal and background sediments in the Bransfield Strait, AntarcticaChanges in gross oxygen production, net oxygen production, and air-water gas exchange during seasonal ice melt in Whycocomagh Bay, a Canadian estuary in the Bras d'Or Lake systemHigh resolution 14C bomb-peak dating and climate response analyses of subseasonal stable isotope signals in wood of the African baobab – A case study from OmanPlants or bacteria? 130 years of mixed imprints in Lake Baldegg sediments (Switzerland), as revealed by compound-specific isotope analysis (CSIA) and biomarker analysisCommercial traceability of Arapaima spp. fisheries in the Amazon basin: can biogeochemical tags be useful?Distribution of Fe isotopes in particles and colloids in the salinity gradient along the Lena River plume, Laptev SeaEarly season N2O emissions under variable water management in rice systems: source-partitioning emissions using isotope ratios along a depth profileEvolution of 231Pa and 230Th in overflow waters of the North AtlanticSouthern Ocean controls of the vertical marine δ13C gradient – a modelling studyNegligible isotopic fractionation of nitrogen within temperate Zostera spp. meadowsEcosystem fluxes of carbonyl sulfide in an old-growth forest: temporal dynamics and responses to diffuse radiation and heat wavesExport flux of unprocessed atmospheric nitrate from temperate forested catchments: a possible new index for nitrogen saturationSilicon isotopes of deep sea sponges: new insights into biomineralisation and skeletal structureLatitudinal trends in stable isotope signatures and carbon-concentrating mechanisms of northeast Atlantic rhodolithsSalinity control on Na incorporation into calcite tests of the planktonic foraminifera Trilobatus sacculifer – evidence from culture experiments and surface sedimentsThe silicon stable isotope distribution along the GEOVIDE section (GEOTRACES GA-01) of the North Atlantic OceanTracing water masses with 129I and 236U in the subpolar North Atlantic along the GEOTRACES GA01 sectionEnvironmental and taxonomic controls of carbon and oxygen stable isotope composition in Sphagnum across broad climatic and geographic rangesEstimation of isotope variation of N2O during denitrification by Pseudomonas aureofaciens and Pseudomonas chlororaphis: implications for N2O source apportionmentImmediate increase in isotopic enrichment in small mammals following the expansion of a great cormorant colonyStomatal control of leaf fluxes of carbonyl sulfide and CO2 in a Typha freshwater marshThe triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrationsShort-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: a 13C pulse-chase experimentδ11B as monitor of calcification site pH in divergent marine calcifying organismsCatchment tracers reveal discharge, recharge and sources of groundwater-borne pollutants in a novel lake modelling approachStable isotopic constraints on global soil organic carbon turnoverSpatial variations in snowpack chemistry, isotopic composition of NO3− and nitrogen deposition from the ice sheet margin to the coast of western GreenlandGlacial–interglacial changes and Holocene variations in Arabian Sea denitrification
Petra Zahajská, Carolina Olid, Johanna Stadmark, Sherilyn C. Fritz, Sophie Opfergelt, and Daniel J. Conley
Biogeosciences, 18, 2325–2345,Short summary
The drivers of high accumulation of single-cell siliceous algae (diatoms) in a high-latitude lake have not been fully characterized before. We studied silicon cycling of the lake through water, radon, silicon, and stable silicon isotope balances. Results showed that groundwater brings 3 times more water and dissolved silica than the stream inlet. We demonstrate that groundwater discharge and low sediment deposition have driven the high diatom accumulation in the studied lake in the past century.
Yu-Te Hsieh, Walter Geibert, E. Malcolm S. Woodward, Neil J. Wyatt, Maeve C. Lohan, Eric P. Achterberg, and Gideon M. Henderson
Biogeosciences, 18, 1645–1671,Short summary
The South Atlantic near 40° S is one of the high-productivity and most dynamic nutrient regions in the oceans, but the sources and fluxes of trace elements (TEs) to this region remain unclear. This study investigates seawater Ra-228 and provides important constraints on ocean mixing and dissolved TE fluxes to this region. Vertical mixing is a more important source than aeolian or shelf inputs in this region, but particulate or winter deep-mixing inputs may be required to balance the TE budgets.
Zhongjie Yu and Emily M. Elliott
Biogeosciences, 18, 805–829,Short summary
In this study, we demonstrated distinct nitrogen isotope effects for nitric oxide (NO) production from major microbial and chemical NO sources in an agricultural soil. These results highlight characteristic bond-forming and breaking mechanisms associated with microbial and chemical NO production and implicate that simultaneous isotopic analyses of NO and nitrous oxide (N2O) can lead to unprecedented insights into the sources and processes controlling NO and N2O emissions from agricultural soils.
Daniel A. Frick, Rainer Remus, Michael Sommer, Jürgen Augustin, Danuta Kaczorek, and Friedhelm von Blanckenburg
Biogeosciences, 17, 6475–6490,Short summary
Silicon is taken up by some plants to increase structural stability and to develop stress resistance and is rejected by others. To explore the underlying mechanisms, we used the stable isotopes of silicon that shift in their relative abundance depending on the biochemical transformation involved. On species with a rejective (tomato, mustard) and active (wheat) uptake mechanism, grown in hydroculture, we found that the transport of silicic acid is controlled by the precipitation of biogenic opal.
Quentin Charbonnier, Julien Bouchez, Jérôme Gaillardet, and Éric Gayer
Biogeosciences, 17, 5989–6015,Short summary
The abundance and isotope composition of the trace metal barium (Ba) allows us to track and quantify nutrient cycling throughout the Amazon Basin. In particular, we show that the Ba biological fingerprint evolves from that of a strong net nutrient uptake in the mountainous area of the Andes towards efficient nutrient recycling on the plains of the Lower Amazon. Our study highlights the fact that the geochemical signature of rock-derived nutrients transported by the Amazon is scarred by life.
Ajinkya G. Deshpande, Thomas W. Boutton, Ayumi Hyodo, Charles W. Lafon, and Georgianne W. Moore
Biogeosciences, 17, 5639–5653,Short summary
Wetland forests in the southern USA are threatened by changing climate and human-induced pressures. We used tree ring widths and C isotopes as indicators of forest growth and physiological stress, respectively, and compared these to past climate data. We observed that vegetation growing in the drier patches is susceptible to stress, while vegetation growth and physiology in wetter patches is less sensitive to unfavorable environmental conditions, highlighting the importance of optimal wetness.
Dominika Lewicka-Szczebak, Maciej Piotr Lewicki, and Reinhard Well
Biogeosciences, 17, 5513–5537,Short summary
We present the first validation of N2O isotopic approaches for estimating N2O source pathways and N2O reduction. These approaches are widely used for tracing soil nitrogen cycling, but the results of these estimations are very uncertain. Here we report the results from parallel treatments allowing for precise validation of these approaches, and we propose the best strategies for results interpretation, including the new idea of an isotope model integrating three isotopic signatures of N2O.
Markus Raitzsch, Claire Rollion-Bard, Ingo Horn, Grit Steinhoefel, Albert Benthien, Klaus-Uwe Richter, Matthieu Buisson, Pascale Louvat, and Jelle Bijma
Biogeosciences, 17, 5365–5375,Short summary
The isotopic composition of boron in carbonate shells of marine unicellular organisms is a popular tool to estimate seawater pH. Usually, many shells need to be dissolved and measured for boron isotopes, but the information on their spatial distribution is lost. Here, we investigate two techniques that allow for measuring boron isotopes within single shells and show that they yield robust mean values but provide additional information on the heterogeneity within and between single shells.
Veronica R. Rollinson, Julie Granger, Sydney C. Clark, Mackenzie L. Blanusa, Claudia P. Koerting, Jamie M. P. Vaudrey, Lija A. Treibergs, Holly C. Westbrook, Catherine M. Matassa, Meredith K. Hastings, and Craig R. Tobias
Revised manuscript accepted for BGShort summary
We measured nutrients and the naturally occurring nitrogen (N) and oxygen (O) stable isotope ratios of nitrate discharged from a New England river over an annual cycle, to monitor N loading and identify dominant sources from the watershed. We uncovered a seasonality to loading and sources of N from the watershed. Seasonality in the nitrate isotope ratios also informed on N cycling, conforming to theoretical expectations of riverine nutrient cycling.
Florian Einsiedl, Anja Wunderlich, Mathieu Sebilo, Ömer K. Coskun, William D. Orsi, and Bernhard Mayer
Biogeosciences, 17, 5149–5161,Short summary
Nitrate pollution of freshwaters and methane emissions into the atmosphere are crucial factors in deteriorating the quality of drinking water and in contributing to global climate change. Here, we report vertical concentration and stable isotope profiles of CH4, NO3-, NO2-, and NH4+ in the water column of Fohnsee (southern Bavaria, Germany) that may indicate linkages between nitrate-dependent anaerobic methane oxidation and the anaerobic oxidation of ammonium.
Zixun Chen, Xuejun Liu, Xiaoqing Cui, Yaowen Han, Guoan Wang, and Jiazhu Li
Revised manuscript accepted for BGShort summary
ẟ13C in plants is a sensitive long-term indicator of physiological acclimatization. The present study suggests that precipitation change and increasing atmospheric N deposition have little impact on ẟ13C of H. ammodendron, a dominant plant in Central Asia deserts, but affect its gas exchange. In addition, this study shows that ẟ13C of H. ammodendron could not indicate its water use efficiency (WUE), suggesting that whether ẟ13C of C4 plants indicates WUE is species-specific dependent.
Ruifang C. Xie, Frédéric A. C. Le Moigne, Insa Rapp, Jan Lüdke, Beat Gasser, Marcus Dengler, Volker Liebetrau, and Eric P. Achterberg
Biogeosciences, 17, 4919–4936,Short summary
Thorium-234 (234Th) is widely used to study carbon fluxes from the surface ocean to depth. But few studies stress the relevance of oceanic advection and diffusion on the downward 234Th fluxes in nearshore environments. Our study in offshore Peru showed strong temporal variations in both the importance of physical processes on 234Th flux estimates and the oceanic residence time of 234Th, whereas salinity-derived seawater 238U activities accounted for up to 40 % errors in 234Th flux estimates.
Ralf A. Oeser and Friedhelm von Blanckenburg
Biogeosciences, 17, 4883–4917,Short summary
We present a novel strategy to decipher the relative impact of biogenic and abiotic drivers of weathering. We parameterized the nutrient fluxes in four ecosystems along a climate and vegetation gradient situated on the Chilean Coastal Cordillera. We investigated how nutrient demand by plants drives weathering. We found that the increase in biomass nutrient demand is accommodated by faster nutrient recycling rather than an increase in the weathering–release rates.
Tito Arosio, Malin M. Ziehmer, Kurt Nicolussi, Christian Schlüchter, and Markus Leuenberger
Biogeosciences, 17, 4871–4882,Short summary
Stable isotopes in tree-ring cellulose are tools for climatic reconstructions, but interpretation is challenging due to nonclimate trends. We analyzed the tree-age trends in tree-ring isotopes of deciduous larch and evergreen cembran pine. Samples covering the whole Holocene were collected at the tree line in the Alps. For cambial ages over 100 years, we prove the absence of age trends in δD, δ18O, and δ13C for both species. For lower cambial ages, trends differ for each isotope and species.
Yuyang He, Xiaobin Cao, and Huiming Bao
Biogeosciences, 17, 4785–4795,Short summary
Different carbon sites in a large organic molecule have different isotope compositions. Different carbon sites may not have the chance to exchange isotopes at all. The lack of appreciation of this notion might be blamed for an unsettled debate on the thermodynamic state of an organism. Here we demonstrate using minerals, N2O, and acetic acid that the dearth of exchange among different carbon sites renders them as independent as if they were different elements in organic molecules.
Felix M. Spielmann, Albin Hammerle, Florian Kitz, Katharina Gerdel, and Georg Wohlfahrt
Biogeosciences, 17, 4281–4295,Short summary
Carbonyl sulfide (COS) can be used as a proxy for plant photosynthesis on an ecosystem scale. However, the relationships between COS and CO2 fluxes and their dependence on daily to seasonal changes in environmental drivers are still poorly understood. We examined COS and CO2 ecosystem fluxes above an agriculturally used mountain grassland for 6 months. Harvesting of the grassland disturbed the otherwise stable COS-to-CO2 uptake ratio. We even found the canopy to release COS during those times.
Getachew Agmuas Adnew, Thijs L. Pons, Gerbrand Koren, Wouter Peters, and Thomas Röckmann
Biogeosciences, 17, 3903–3922,Short summary
We measured the effect of photosynthesis, the largest flux in the carbon cycle, on the triple oxygen isotope composition of atmospheric CO2 at the leaf level during gas exchange using three plant species. The main factors that limit the impact of land vegetation on the triple oxygen isotope composition of atmospheric CO2 are identified, characterized and discussed. The effect of photosynthesis on the isotopic composition of CO2 is commonly quantified as discrimination (ΔA).
Moritz Schroll, Frank Keppler, Markus Greule, Christian Eckhardt, Holger Zorn, and Katharina Lenhart
Biogeosciences, 17, 3891–3901,Short summary
Fungi have recently been identified to produce the greenhouse gas methane. Here, we investigated the stable carbon isotope values of methane produced by saprotrophic fungi. Our results show that stable isotope values of methane from fungi are dependent on the fungal species and the metabolized substrate. They cover a broad range and overlap with stable carbon isotope values of methane reported for methanogenic archaea, the thermogenic degradation of organic matter, and other eukaryotes.
Pranav Hirave, Guido L. B. Wiesenberg, Axel Birkholz, and Christine Alewell
Biogeosciences, 17, 2169–2180,Short summary
Sediment input into water bodies is a prominent threat to freshwater ecosystems. We tested the stability of tracers employed in freshwater sediment tracing based on compound-specific isotope analysis during early degradation in soil. While bulk δ13C values showed no stability, δ13C values of plant-derived fatty acids and n-alkanes were stably transferred to the soil without soil particle size dependency after an early degradation in organic horizons, thus indicating their suitability as tracers.
Caroline Thaler, Amandine Katz, Magali Bonifacie, Bénédicte Ménez, and Magali Ader
Biogeosciences, 17, 1731–1744,Short summary
Paleoenvironment reconstructions, retrieved from δ18O and Δ47 values measured in carbonate, are compromised when crystallization occurs in isotopic disequilibrium. We show that some paleoenvironmental information can still be retrieved from these paired disequilibrium Δ47 and δ18O values. The possibility of retrieving information on paleowaters, sediments' interstitial waters, or organisms' body water at the carbonate precipitation loci will help understand past Earth and life evolution.
Guillaume Humbert, Mathieu Sébilo, Justine Fiat, Longqi Lang, Ahlem Filali, Véronique Vaury, Mathieu Spérandio, and Anniet M. Laverman
Biogeosciences, 17, 979–993,Short summary
Mitigating emissions of the greenhouse gas N2O requires understanding of the relative contribution of its producing processes in response to environmental variables. We show, using isotopic analysis, that N2O emissions from a nitrifying system were sensitive to oxygenation, temperature and NH4+ concentrations with nitrite reduction being the main N2O source. Temperature appears to be the main control on N2O production, due to its dissimilar effects on ammonium and nitrite oxidizing activities.
Oguz Yigiterhan, Ebrahim Mohd Al-Ansari, Alex Nelson, Mohamed Alaa Abdel-Moati, Jesse Turner, Hamood Abdulla Alsaadi, Barbara Paul, Ibrahim Abdullatif Al-Maslamani, Mehsin Abdulla Al-Ansi Al-Yafei, and James W. Murray
Biogeosciences, 17, 381–404,Short summary
We analyze net-tow samples of plankton and associated particulate matter from the Exclusive Economic Zone, Qatar, Arabian Gulf, using net tows with mesh sizes of 50 and 200 μm to examine the composition of plankton populations. We also focus on the role and composition of the atmospheric dust, representative of terrigenous material, deposited in the Gulf. We concluded that Al, Fe, Cr, Co, Mn, Ni, Pb, and Li are of dust origin and As, Cd, Cu, Mo, Zn, and Ca are of anthropogenic/biogenic origin.
Clare Woulds, James B. Bell, Adrian G. Glover, Steven Bouillon, and Louise S. Brown
Biogeosciences, 17, 1–12,Short summary
Sedimented hydrothermal vents occur where heated, mineral-rich (hydrothermal) water seeps through seafloor sediments. They host chemosynthetic microbes, which use chemical energy to fix dissolved carbon dioxide into sugars (chemosynthesis). We conducted carbon tracing experiments, and observed chemosynthesis at both vent and non-vent sites. Thus, chemosynthesis occurred over a much larger area than expected, suggesting it is more widespread than previously thought.
Cara C. Manning, Rachel H. R. Stanley, David P. Nicholson, Brice Loose, Ann Lovely, Peter Schlosser, and Bruce G. Hatcher
Biogeosciences, 16, 3351–3376,Short summary
We measured rates of biological activity and gas exchange in a Canadian estuary during ice melt. We quantified gas exchange using inert, deliberately released tracers and found that the gas transfer rate at > 90 % ice cover was 6 % of the rate for nearly ice-free conditions. We measured oxygen concentration and isotopic composition and used the data to detect changes in the rates of photosynthesis and respiration (autotrophy and heterotrophy) as the ice melted.
Franziska Slotta, Lukas Wacker, Frank Riedel, Karl-Uwe Heußner, Kai Hartmann, and Gerhard Helle
Revised manuscript accepted for BGShort summary
The African baobab is a challenging climate- and environmental archive for its semi-arid habitat due to dating uncertainties and parenchyma-rich wood anatomy. Annually resolved F14C data of tree-ring cellulose (1941–2005) from a tree in Oman shows the annual character of the baobab's growth rings but were found up to 8.8 % lower than expected for 1964–1967. Sub-seasonal δ13C and δ18O patterns reveal years with low average monsoon rain as well as heavy rainfall events from pre-monsoonal cyclones.
Marlène Lavrieux, Axel Birkholz, Katrin Meusburger, Guido L. B. Wiesenberg, Adrian Gilli, Christian Stamm, and Christine Alewell
Biogeosciences, 16, 2131–2146,Short summary
A fingerprinting approach using compound-specific stable isotopes was applied to a lake sediment core to reconstruct erosion processes over the past 150 years in a Swiss catchment. Even though the reconstruction of land use and eutrophication history was successful, the observation of comparatively low δ13C values of plant-derived fatty acids in the sediment suggests their alteration within the lake. Thus, their use as a tool for source attribution in sediment cores needs further investigation.
Luciana A. Pereira, Roberto V. Santos, Marília Hauser, Fabrice Duponchelle, Fernando Carvajal, Christophe Pecheyran, Sylvain Bérail, and Marc Pouilly
Biogeosciences, 16, 1781–1797,Short summary
This study presents the first step for a chemical origin certification of pirarucu fishery in the Amazon. A preliminary isotopic tool to improve the actual tracking system integrates ecological, social, and economic aspects of Amazon dynamics. The geographic origin validation of farmed and wild fishes contributes to environmental and social practices, secures food and income to communities, helps manage endangered species, reinforces aquaculture, and combats illegal fisheries.
Sarah Conrad, Johan Ingri, Johan Gelting, Fredrik Nordblad, Emma Engström, Ilia Rodushkin, Per S. Andersson, Don Porcelli, Örjan Gustafsson, Igor Semiletov, and Björn Öhlander
Biogeosciences, 16, 1305–1319,Short summary
Iron analysis of the particulate, colloidal, and truly dissolved fractions along the Lena River freshwater plume showed that the particulate iron dominates close to the coast. Over 99 % particulate and about 90 % colloidal iron were lost, while the truly dissolved phase was almost constant. Iron isotopes suggest that the shelf acts as a sink for particles and colloids with negative iron isotope values, while colloids with positive iron isotope values travel further out into the Arctic Ocean.
Elizabeth Verhoeven, Matti Barthel, Longfei Yu, Luisella Celi, Daniel Said-Pullicino, Steven Sleutel, Dominika Lewicka-Szczebak, Johan Six, and Charlotte Decock
Biogeosciences, 16, 383–408,Short summary
This study utilized state-of-the-art measurements of nitrogen isotopes to evaluate nitrogen cycling and to assess the biological sources of the potent greenhouse gas, N2O, in response to water-saving practices in rice systems. Water-saving practices did emit more N2O, and high N2O production had a lower 15N isotope signature. Modeling and visual interpretation indicate that these emissions mostly came from denitrification or nitrifier denitrification, controlled upstream by nitrification rates.
Feifei Deng, Gideon M. Henderson, Maxi Castrillejo, Fiz F. Perez, and Reiner Steinfeldt
Biogeosciences, 15, 7299–7313,Short summary
To better use Pa / Th to reconstruct deep water ventilation rate, we assessed controls on 230Th and 231Pa in the northern North Atlantic. With extended optimum multi-parameter analysis and CFC-based water-mass age, we found the imprint of young overflow water on Th and Pa and enhanced scavenging near the seafloor. A significantly higher advective loss of Pa to the south relative to Th in the Atlantic was estimated, supporting the use of Pa / Th for assessing basin-scale meridional transport.
Anne L. Morée, Jörg Schwinger, and Christoph Heinze
Biogeosciences, 15, 7205–7223,Short summary
Changes in the distribution of the carbon isotope 13C can be used to study the climate system if the governing processes (ocean circulation and biogeochemistry) are understood. We show the Southern Ocean importance for the global 13C distribution and that changes in 13C can be strongly influenced by biogeochemistry. Interpretation of 13C as a proxy for climate signals needs to take into account the effects of changes in biogeochemistry in addition to changes in ocean circulation.
Douglas G. Russell, Wei Wen Wong, and Perran L. M. Cook
Biogeosciences, 15, 7225–7234,Short summary
Nitrogen is an important nutrient in marine environments and is continually converted from one form to another. One way these processes can be investigated is by looking at the ratio of the 15N and 14N stable isotopes of different nitrogen-containing compounds. To date few studies have compared these ratios in seagrass beds, their associated sediments and the porewater NH4+ pool. The strong relationship between these nitrogen pools suggests that nitrogen is tightly recycled within seagrass beds.
Bharat Rastogi, Max Berkelhammer, Sonia Wharton, Mary E. Whelan, Frederick C. Meinzer, David Noone, and Christopher J. Still
Biogeosciences, 15, 7127–7139,Short summary
Carbonyl sulfide (OCS) has gained prominence as an independent tracer for gross primary productivity, which is usually modelled by partitioning net CO2 fluxes. Here, we present a simple empirical model for estimating ecosystem-scale OCS fluxes for a temperate old-growth forest and find that OCS sink strength scales with independently estimated CO2 uptake and is sensitive to the the fraction of downwelling diffuse light. We also examine the response of OCS and CO2 fluxes to sequential heat waves.
Fumiko Nakagawa, Urumu Tsunogai, Yusuke Obata, Kenta Ando, Naoyuki Yamashita, Tatsuyoshi Saito, Shigeki Uchiyama, Masayuki Morohashi, and Hiroyuki Sase
Biogeosciences, 15, 7025–7042,Short summary
To clarify the biological processing of nitrate within temperate forested catchments using unprocessed atmospheric nitrate exported from each catchment as a tracer, we continuously monitored stream nitrate concentrations and stable isotopic compositions in three forested catchments for more than 2 years. We concluded that the export flux of unprocessed atmospheric nitrate relative to the deposition flux in each forest ecosystem is applicable as an index for nitrogen saturation.
Lucie Cassarino, Christopher D. Coath, Joana R. Xavier, and Katharine R. Hendry
Biogeosciences, 15, 6959–6977,Short summary
Using a simple model, we show that the silicon isotopic composition of sponges can be used to estimate the silicic acid concentration of seawater, a key parameter linked to nutrient and carbon cycling. However, our data illustrate that skeletal type and growth rate also control silicon isotopic composition of sponges. Our study demonstrates the paleoceanographic utility of sponges as an archive for ocean silica content provided that suitable skeleton types are selected.
Laurie C. Hofmann and Svenja Heesch
Biogeosciences, 15, 6139–6149,Short summary
The ability of marine macroalgae to adapt to changing ocean chemistry will depend on the flexibility of their inorganic carbon uptake mechanisms across biogeographic ranges. Therefore, we investigated the plasticity of inorganic carbon uptake mechanisms in north Atlantic rhodoliths – free-living calcifying red algae that form important benthic habitats in coastal environments. We observed flexible mechanisms related to seawater DIC concentrations, indicating the potential for adaptation.
Jacqueline Bertlich, Dirk Nürnberg, Ed C. Hathorne, Lennart J. de Nooijer, Eveline M. Mezger, Markus Kienast, Steffanie Nordhausen, Gert-Jan Reichart, Joachim Schönfeld, and Jelle Bijma
Biogeosciences, 15, 5991–6018,
Jill N. Sutton, Gregory F. de Souza, Maribel I. García-Ibáñez, and Christina L. De La Rocha
Biogeosciences, 15, 5663–5676,Short summary
The silicon stable isotope distribution determined from samples collected from the North Atlantic Ocean indicates that water mass subduction and circulation are the dominant processes controlling the distribution of dissolved silicon in this region. In addition, these data provide a clear view of the direct interaction between northern and southern water masses and the extent to which the silicon isotope composition of these silica-poor waters is influenced by hydrography.
Maxi Castrillejo, Núria Casacuberta, Marcus Christl, Christof Vockenhuber, Hans-Arno Synal, Maribel I. García-Ibáñez, Pascale Lherminier, Géraldine Sarthou, Jordi Garcia-Orellana, and Pere Masqué
Biogeosciences, 15, 5545–5564,Short summary
The investigation of water mass transport pathways and timescales is important to understand the global ocean circulation. Following earlier studies, we use artificial radionuclides introduced to the oceans in the 1950s to investigate the water transport in the subpolar North Atlantic (SPNA). For the first time, we combine measurements of the long-lived iodine-129 and uranium-236 to confirm earlier findings/hypotheses and to better understand shallow and deep ventilation processes in the SPNA.
Gustaf Granath, Håkan Rydin, Jennifer L. Baltzer, Fia Bengtsson, Nicholas Boncek, Luca Bragazza, Zhao-Jun Bu, Simon J. M. Caporn, Ellen Dorrepaal, Olga Galanina, Mariusz Gałka, Anna Ganeva, David P. Gillikin, Irina Goia, Nadezhda Goncharova, Michal Hájek, Akira Haraguchi, Lorna I. Harris, Elyn Humphreys, Martin Jiroušek, Katarzyna Kajukało, Edgar Karofeld, Natalia G. Koronatova, Natalia P. Kosykh, Mariusz Lamentowicz, Elena Lapshina, Juul Limpens, Maiju Linkosalmi, Jin-Ze Ma, Marguerite Mauritz, Tariq M. Munir, Susan M. Natali, Rayna Natcheva, Maria Noskova, Richard J. Payne, Kyle Pilkington, Sean Robinson, Bjorn J. M. Robroek, Line Rochefort, David Singer, Hans K. Stenøien, Eeva-Stiina Tuittila, Kai Vellak, Anouk Verheyden, James Michael Waddington, and Steven K. Rice
Biogeosciences, 15, 5189–5202,Short summary
Peat constitutes a long-term archive for climate reconstruction by using the isotopic composition of carbon and oxygen. We analysed isotopes in two peat moss species across North America and Eurasia. Peat (moss tissue) isotope composition was predicted by soil moisture and isotopic composition of the rainwater but differed between species. Our results suggest that isotope composition can be used on a large scale for climatic reconstructions but that such models should be species-specific.
Joshua A. Haslun, Nathaniel E. Ostrom, Eric L. Hegg, and Peggy H. Ostrom
Biogeosciences, 15, 3873–3882,Short summary
N2O δ15N and δ18O values changed non-linearly during in vitro N2O production by bacterial denitrification of NO3−, an argument against their use in N2O apportionment. We present a novel approach for describing non-linear isotopic behaviour, which may be applied to other multi-step reactions. We also show that the intramolecular distribution of 15N in N2O, used to apportion N2O emissions to denitrification and nitrification, is unaffected by electron donor source and electron donor concentration.
Linas Balčiauskas, Raminta Skipitytė, Marius Jasiulionis, Laima Balčiauskienė, and Vidmantas Remeikis
Biogeosciences, 15, 3883–3891,Short summary
Effects of an expanding great cormorant colony on small mammals were evaluated. An increase of the number of bird pairs led to decreased δ13C and increased δ15N values in mice hair after the first year of nest appearance. Differences in isotopic signatures were related to species of rodents, pointing to the differences in their diet. Cormorant influence was indirect, the result of biological pollution from guano on rodent foods. Scaring cormorants from the colonies may have the opposite effect.
Wu Sun, Kadmiel Maseyk, Céline Lett, and Ulli Seibt
Biogeosciences, 15, 3277–3291,Short summary
Carbonyl sulfide (COS) is an emerging tracer to probe land photosynthesis at canopy to global scales, but the relationship between leaf COS and CO2 fluxes needed for this application is poorly quantified. With in situ leaf fluxes of COS and CO2 measured in a freshwater marsh, we show that light and vapor deficit control the relationship between leaf COS and CO2 fluxes by regulating stomatal conductance. Our findings support the use of COS as a tracer for canopy photosynthesis.
Anne Alexandre, Amarelle Landais, Christine Vallet-Coulomb, Clément Piel, Sébastien Devidal, Sandrine Pauchet, Corinne Sonzogni, Martine Couapel, Marine Pasturel, Pauline Cornuault, Jingming Xin, Jean-Charles Mazur, Frédéric Prié, Ilhem Bentaleb, Elizabeth Webb, Françoise Chalié, and Jacques Roy
Biogeosciences, 15, 3223–3241,Short summary
There is a lack of proxies suitable for reconstructing, in a quantitative way, past changes in continental atmospheric humidity, which is a key climate parameter. Here, we demonstrate through climate chamber and climate transect calibrations that the triple oxygen isotope composition of phytoliths offers a potential for reconstructing changes in relative humidity.
Philip M. Riekenberg, Joanne M. Oakes, and Bradley D. Eyre
Biogeosciences, 15, 2873–2889,Short summary
Shallow coastal waters are increasingly experiencing increased nutrient loading. Sediment algae within these systems are responsible for a large portion of C production, but we have limited knowledge of what happens to sediment microbial processing of MPB-C under increased nutrient conditions. This work examines how C-processing pathways change after increased short-term nutrient exposure, finding shifts in processing between microbial groups and increased export of algal C from the sediment.
Jill N. Sutton, Yi-Wei Liu, Justin B. Ries, Maxence Guillermic, Emmanuel Ponzevera, and Robert A. Eagle
Biogeosciences, 15, 1447–1467,Short summary
The boron isotope composition of marine biogenic carbonates has been studied as a proxy for monitoring past changes in seawater pH and carbonate chemistry. We highlight the potential utility of the boron isotope composition of marine biogenic carbonates as a proxy of calcifying site pH for a wide range of calcifying taxa and the importance of using species-specific seawater-pH–boron isotope calibrations when reconstructing seawater pH from the boron isotope composition of biogenic carbonates.
Emil Kristensen, Mikkel Madsen-Østerbye, Philippe Massicotte, Ole Pedersen, Stiig Markager, and Theis Kragh
Biogeosciences, 15, 1203–1216,Short summary
We propose a novel modelling approach enabling swift hydrological surveys based on multiple conservative and non-conservative tracers to estimate water retention time, groundwater discharge sites, fractions of water originating from the discharge sites, groundwater recharge sites and sites that are especially important in regard to groundwater recharge. Thus we provide a whole lake hydrological survey while pinpointing sources of pollutants like colored dissolved organic matter and nutrients.
Chao Wang, Benjamin Z. Houlton, Dongwei Liu, Jianfeng Hou, Weixin Cheng, and Edith Bai
Biogeosciences, 15, 987–995,Short summary
Soil contains a large amount of organic carbon and plays a crucial role in regulating Earth's C cycle and climate system. In this study, we collected soil-carbon isotope data within a 1 m depth globally and provided an isotope-based approach for understanding soil carbon decomposition rate. Compared with other methods, utilization of C isotope composition ratios in the soil profile provides an independent approach that does not rely on disruption of plant-soil-microbe interactions.
Chris J. Curtis, Jan Kaiser, Alina Marca, N. John Anderson, Gavin Simpson, Vivienne Jones, and Erika Whiteford
Biogeosciences, 15, 529–550,Short summary
Few studies have investigated the atmospheric deposition of nitrate in the Arctic or its impacts on Arctic ecosystems. We collected late-season snowpack from three regions in western Greenland from the coast to the edge of the ice sheet. We found major differences in nitrate concentrations (lower at the coast) and deposition load (higher). Nitrate in snowpack undergoes losses and isotopic enrichment which are greatest in inland areas; hence deposition impacts may be greatest at the coast.
Birgit Gaye, Anna Böll, Joachim Segschneider, Nicole Burdanowitz, Kay-Christian Emeis, Venkitasubramani Ramaswamy, Niko Lahajnar, Andreas Lückge, and Tim Rixen
Biogeosciences, 15, 507–527,Short summary
The Arabian Sea has one of the most severe oxygen minima of the world's oceans between about 100 and 1200 m of water depth and is therefore a major oceanic nitrogen sink. Stable nitrogen isotopic ratios in sediments record changes in oxygen concentrations and were studied for the last 25 kyr. Oxygen concentrations dropped at the end of the last glacial and became further reduced during the Holocene, probably due to the increasing age of the low-oxygen water mass.
Adam, G. and Duncan, H.: Development of a sensitive and rapid method for the measurement of total microbial activity using fluorescein diacetate (FDA) in a range of soils, Soil Biol. Biochem., 33, 943–951, 2001.
Andrade, G., Mihara, K. L., Linderman, R. G., and Bethlenfalvay, G. J.: Bacteria from rhizosphere and hyphosphere soils of different arbuscular-mycorrhizal fungi, Plant Soil, 192, 71–79, https://doi.org/10.1023/A:1004249629643, 1997.
Bååth, E. and Söderström, B.: The significance of hyphal diameter in calculation of fungal biovolume, Oikos, 33, 11–14, 1979.
Bahn, M., Rodeghiero, M., Anderson-Dunn, M., Dore, S., Gimeno, C., Drösler, M., Williams, M., Ammann, C., Berninger, F., Flechard, C., Jones, S., Balzarolo, M., Kumar, S., Newesely, C., Priwitzer, T., Raschi, A., Siegwolf, R., Susiluoto, S., Tenhunen, J., Wohlfahrt, G., and Cernusca, A.: Soil Respiration in European Grasslands in Relation to Climate and Assimilate Supply, Ecosystems, 11, 1352–1367, https://doi.org/10.1007/s10021-008-9198-0, 2008.
Balogh, J., Pintér, K., Fóti, S., Cserhalmi, D., Papp, M., and Nagy, Z.: Dependence of soil respiration on soil moisture, clay content, soil organic matter, and CO2 uptake in dry grasslands, Soil Biol. Biochem., 43, 1006–1013, https://doi.org/10.1016/j.soilbio.2011.01.017, 2011.
Balogh, J., Fóti, S., Pintér, K., Burri, S., Eugster, W., Papp, M., and Nagy, Z.: Soil CO2 efflux and production rates as influenced by evapotranspiration in a dry grassland, Plant Soil, 388, 157–173, https://doi.org/10.1007/s11104-014-2314-3, 2015.
Bao, F., Zhou, G., Wang, F., and Sui, X.: Partitioning soil respiration in a temperate desert steppe in Inner Mongolia using exponential regression method, Soil Biol. Biochem., 42, 2339–2341, https://doi.org/10.1016/j.soilbio.2010.08.033, 2010.
Barcza, Z., Haszpra, L., and Kondo, H.: Carbon exchange of grass in Hungary, Tellus B, 55, 187–196, https://doi.org/10.1034/j.1600-0889.2003.00014.x, 2003.
Bardgett, R. D., Freeman, C., and Ostle, N. J.: Microbial contributions to climate change through carbon cycle feedbacks, ISME J., 2, 805–814, https://doi.org/10.1038/ismej.2008.58, 2008.
Blagodatsky, S. and Smith, P.: Soil physics meets soil biology: Towards better mechanistic prediction of greenhouse gas emissions from soil, Soil Biol. Biochem., 47, 78–92, https://doi.org/10.1016/j.soilbio.2011.12.015, 2012.
Bowling, D., McDowell, N., Bond, B., Law, B., and Ehleringer, J.: 13C content of ecosystem respiration is linked to precipitation and vapor pressure deficit, Oecologia, 131, 113–124, https://doi.org/10.1007/s00442-001-0851-y, 2002.
Bowling, D. R., Pataki, D. E., and Randerson, J. T.: Carbon isotopes in terrestrial ecosystem pools and CO2 fluxes, New Phytol., 178, 24–40, https://doi.org/10.1111/j.1469-8137.2007.02342.x, 2008.
Carbone, M. S., Winston, G. C., and Trumbore, S. E.: Soil respiration in perennial grass and shrub ecosystems: Linking environmental controls with plant and microbial sources on seasonal and diel timescales, J. Geophys. Res., 113, G02022, https://doi.org/10.1029/2007JG000611, 2008.
Carbone, M. S., Still, C. J., Ambrose, A. R., Dawson, T. E., Williams, A. P., Boot, C. M., Schaeffer, S. M., and Schimel, J. P.: Seasonal and episodic moisture controls on plant and microbial contributions to soil respiration, Oecologia, 167, 265–78, https://doi.org/10.1007/s00442-011-1975-3, 2011.
Casals, P., Lopez-Sangil, L., Carrara, A., Gimeno, C., and Nogués, S.: Autotrophic and heterotrophic contributions to short-term soil CO2 efflux following simulated summer precipitation pulses in a Mediterranean dehesa, Global Biogeochem. Cy., 25, GB3012, https://doi.org/10.1029/2010GB003973, 2011.
Chen, S., Lin, G., Huang, J., and Jenerette, G. D.: Dependence of carbon sequestration on the differential responses of ecosystem photosynthesis and respiration to rain pulses in a semiarid steppe, Glob. Change Biol., 15, 2450–2461, https://doi.org/10.1111/j.1365-2486.2009.01879.x, 2009.
Davidson, E. A., Samanta, S., Caramori, S. S., and Savage, K.: The Dual Arrhenius and Michaelis-Menten kinetics model for decomposition of soil organic matter at hourly to seasonal time scales, Glob. Change Biol., 18, 371–384, https://doi.org/10.1111/j.1365-2486.2011.02546.x, 2012.
Denef, K., Galdo, I., Venturi, A., and Cotrufo, M.: Assessment of Soil C and N Stocks and Fractions across 11 European Soils under Varying Land Uses, Open J. Soil Sci., 3, 297–313, 2013.
Epron, D.: Separating autotrophic and heterotrophic components of soil respiration: lessons learned from trenching and related root exclusion experiments, in Soil Carbon Dynamics: An Integrated Methodology, edited by: Bahn, M., Heinemeyer, A., and Kutsch, W., Cambridge University Press, 289–310, 2009.
Farkas, C., Alberti, G., Balogh, J., Barcza, Z., Birkas, M., Czobel, S., Davis, K. J., Fuehrer, E., Gelybo, G., Grosz, B., Kljun, N., Koos, S., Machon, A., Marjanovic, H., Nagy, Z., Peressotti, A., Pinter, K., Toth, E., and Horvath, L.: Methodologies, in Atmospheric Greenhouse Gases: The Hungarian Perspective, edited by: Haszpra, L., 65–90, Springer, New York, 2011.
Fassbinder, J. J., Griffis, T. J., and Baker, J. M.: Interannual, seasonal, and diel variability in the carbon isotope composition of respiration in a C3/C4 agricultural ecosystem, Agr. Forest Meteorol., 153, 144–153, https://doi.org/10.1016/j.agrformet.2011.09.018, 2011.
Gamnitzer, U., Moyes, A. B., Bowling, D. R., and Schnyder, H.: Measuring and modelling the isotopic composition of soil respiration: insights from a grassland tracer experiment, Biogeosciences, 8, 1333–1350, https://doi.org/10.5194/bg-8-1333-2011, 2011.
Gomez-Casanovas, N., Matamala, R., Cook, D. R., and Gonzalez-Meler, M. a.: Net ecosystem exchange modifies the relationship between the autotrophic and heterotrophic components of soil respiration with abiotic factors in prairie grasslands, Glob. Change Biol., 18, 2532–2545, https://doi.org/10.1111/j.1365-2486.2012.02721.x, 2012.
Heinemeyer, A., Tortorella, D., Petrovičová, B., and Gelsomino, A.: Partitioning of soil CO2 flux components in a temperate grassland ecosystem, Eur. J. Soil Sci., 63, 249–260, https://doi.org/10.1111/j.1365-2389.2012.01433.x, 2012.
Hiiesalu, I., Partel, M., Davison, J., Gerhold, P., Metsis, M., Moora, M., Öpik, M., Vasar, M., Zobel, M., and Wilson, S. D.: Species richness of arbuscular mycorrhizal fungi: Associations with grassland plant richness and biomass, New Phytol., 203, 233–244, https://doi.org/10.1111/nph.12765, 2014.
Hoover, D., Knapp, A., and Smith, M.: Resistance and resilience of a grassland ecosystem to climate extremes, Ecology, 95, 2646–2656, https://doi.org/10.1890/13-2186.1, 2014.
Hopkins, F., Gonzalez-Meler, M. A., Flower, C. E., Lynch, D. J., Czimczik, C., Tang, J., and Subke, J.-A.: Ecosystem-level controls on root-rhizosphere respiration, New Phytol., 199, 339–51, 2013.
Knohl, A., Werner, R. A., Brand, W. A., and Buchmann, N.: Short-term variations in δ13C of ecosystem respiration reveals link between assimilation and respiration in a deciduous forest, Oecologia, 142, 70–82, https://doi.org/10.1007/s00442-004-1702-4, 2005.
Koncz, P., Besnyői, V., Csathó, A. I., Nagy, J., Szerdahelyi, T., Tóth, Z., Pintér, K., Balogh, J., Nagy, Z., and Bartha, S.: Effect of grazing and mowing on the microcoenological composition of semi-arid grassland in Hungary, Appl. Ecol. Environ. Res., 12, 563–575, https://doi.org/10.15666/aeer/1202_563575, 2014.
Lo, E.: Gaussian Error Propagation Applied To Ecological Data: Post-Ice-Storm-Downed Woody Biomass, Ecol. Monogr., 75, 451–466, https://doi.org/10.1890/05-0030, 2005.
Midwood, A. J. and Millard, P.: Challenges in measuring the δ13C of the soil surface CO2 efflux, Rapid Commun. Mass Spectrom., 25, 232–242, https://doi.org/10.1002/rcm.4857, 2011.
Moyano, F., Kutsch, W., and Schulze, E.: Response of mycorrhizal, rhizosphere and soil basal respiration to temperature and photosynthesis in a barley field, Soil Biol. Biochem., 39, 843–853, https://doi.org/10.1016/j.soilbio.2006.10.001, 2007.
Moyano, F., Atkin, O., Bahn, M., Bruhn, D., Burton, A., Heinemeyer, A., WL, K., and Wieser, G.: Respiration from roots and the mycorrhizosphere, in Soil Carbon Dynamics: An Integrated Methodology, edited by: Bahn, M., Heinemeyer, A., and Kutsch, W. L., 234–288, Cambridge University Press, 2009.
Moyano, F. E., Manzoni, S., and Chenu, C.: Responses of soil heterotrophic respiration to moisture availability: An exploration of processes and models, Soil Biol. Biochem., 59, 72–85, https://doi.org/10.1016/j.soilbio.2013.01.002, 2013.
Moyes, A. B., Gaines, S. J., Siegwolf, R. T. W., and Bowling, D. R.: Diffusive fractionation complicates isotopic partitioning of autotrophic and heterotrophic sources of soil respiration, Plant Cell Environ., 33, 1804–19, https://doi.org/10.1111/j.1365-3040.2010.02185.x, 2010.
Mummey, D. L. and Rillig, M. C.: Spatial characterization of arbuscular mycorrhizal fungal molecular diversity at the submetre scale in a temperate grassland, FEMS Microbiol. Ecol., 64, 260–270, https://doi.org/10.1111/j.1574-6941.2008.00475.x, 2008.
Nagy, Z., Pintér, K., Czóbel, S., Balogh, J., Horváth, L., Fóti, S., Barcza, Z., Weidinger, T., Csintalan, Z., Dinh, N. Q., Grosz, B., and Tuba, Z.: The carbon budget of semi-arid grassland in a wet and a dry year in Hungary, Agr. Ecosyst. Environ., 121, 21–29, https://doi.org/10.1016/j.agee.2006.12.003, 2007.
Nagy, Z., Pintér, K., Pavelka, M., Darenová, E., and Balogh, J.: Carbon fluxes of surfaces vs. ecosystems: advantages of measuring eddy covariance and soil respiration simultaneously in dry grassland ecosystems, Biogeosciences, 8, 2523–2534, https://doi.org/10.5194/bg-8-2523-2011, 2011.
Nickerson, N. and Risk, D.: A numerical evaluation of chamber methodologies used in measuring the δ13C of soil respiration, Rapid Commun. Mass Spectrom., 23, 2802–2810, https://doi.org/10.1002/rcm.4189, 2009.
Nickerson, N., Egan, J., and Risk, D.: Iso-FD: A novel method for measuring the isotopic signature of surface flux, Soil Biol. Biochem., 62, 99–106, https://doi.org/10.1016/j.soilbio.2013.03.010, 2013.
Parton, W., Morgan, J., Smith, D., Del Grosso, S., Prihodko, L., Lecain, D., Kelly, R., and Lutz, S.: Impact of precipitation dynamics on net ecosystem productivity, Glob. Change Biol., 18, 915–927, https://doi.org/10.1111/j.1365-2486.2011.02611.x, 2012.
Phillips, C. and Nickerson, N.: Soil moisture effects on the carbon isotope composition of soil respiration, Rapid Commun. Mass Spectrom., 1271–1280, https://doi.org/10.1002/rcm.4511, 2010.
Pintér, K., Balogh, J., and Nagy, Z.: Ecosystem scale carbon dioxide balance of two grasslands in Hungary under different weather conditions, Acta Biol. Hung., 61, 130–135, https://doi.org/10.1556/ABiol.61.2010.Suppl.13, 2010.
Prudhomme, C., Giuntoli, I., Robinson, E. L., Clark, D. B., Arnell, N. W., Dankers, R., Fekete, B. M., Franssen, W., Gerten, D., Gosling, S. N., Hagemann, S., Hannah, D. M., Kim, H., Masaki, Y., Satoh, Y., Stacke, T., Wada, Y., and Wisser, D.: Hydrological droughts in the 21st century, hotspots and uncertainties from a global multimodel ensemble experiment, P. Natl. Acad. Sci. USA, 111, 3262–3267, https://doi.org/10.1073/pnas.1222473110, 2014.
R Core Team: R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing, Vienna, Austria, 2014.
Reichstein, M., Bahn, M., Ciais, P., Frank, D., Mahecha, M. D., Seneviratne, S. I., Zscheischler, J., Beer, C., Buchmann, N., Frank, D. C., Papale, D., Rammig, A., Smith, P., Thonicke, K., van der Velde, M., Vicca, S., Walz, A., and Wattenbach, M.: Climate extremes and the carbon cycle, Nature, 500, 287–295, https://doi.org/10.1038/nature12350, 2013.
Risk, D., Nickerson, N., Creelman, C., McArthur, G., and Owens, J.: Forced Diffusion soil flux: A new technique for continuous monitoring of soil gas efflux, Agr. Forest Meteorol., 151, 1622–1631, https://doi.org/10.1016/j.agrformet.2011.06.020, 2011.
Risk, D., Nickerson, N., Phillips, C. L., Kellman, L., and Moroni, M.: Drought alters respired δ13CO2 from autotrophic, but not heterotrophic soil respiration, Soil Biol. Biochem., 50, 26–32, https://doi.org/10.1016/j.soilbio.2012.01.025, 2012.
Suseela, V. and Dukes, J.: The responses of soil and rhizosphere respiration to simulated climatic changes vary by season, Ecology, 94, 403–413, https://doi.org/abs/10.1890/12-0150.1, 2013.
Tennant, D.: A test of a modified line intersect method of estimating root length, J. Ecol., 63, 995–1001, 1975.
van der Heijden, M. G. A., Bardgett, R. D., and van Straalen, N. M.: The unseen majority: soil microbes as drivers of plant diversity and productivity in terrestrial ecosystems, Ecol. Lett., 11, 296–310, https://doi.org/10.1111/j.1461-0248.2007.01139.x, 2008.
van der Heijden, M. G. A., Martin, F. M., Selosse, M.-A., and Sanders, I. R.: Mycorrhizal ecology and evolution: the past, the present, and the future, New Phytol., 205, 1406–1423, https://doi.org/10.1111/nph.13288, 2015.
van der Molen, M. K., Dolman, A. J., Ciais, P., Eglin, T., Gobron, N., Law, B. E., Meir, P., Peters, W., Phillips, O. L., Reichstein, M., Chen, T., Dekker, S. C., Doubková, M., Friedl, M. A., Jung, M., van den Hurk, B. J. J. M., de Jeu, R. A. M., Kruijt, B., Ohta, T., Rebel, K. T., Plummer, S., Seneviratne, S. I., Sitch, S., Teuling, A. J., van der Werf, G. R., and Wang, G.: Drought and ecosystem carbon cycling, Agr. Forest Meteorol., 151, 765–773, https://doi.org/10.1016/j.agrformet.2011.01.018, 2011.
Vargas, R., Detto, M., Baldocchi, D. D., and Allen, M. F.: Multiscale analysis of temporal variability of soil CO2 production as influenced by weather and vegetation, Glob. Change Biol., 16, 1589–1605, https://doi.org/10.1111/j.1365-2486.2009.02111.x, 2010.
Yang, F. and Zhou, G.: Sensitivity of temperate desert steppe carbon exchange to seasonal droughts and precipitation variations in Inner Mongolia, China, PLoS One, 8, e55418, https://doi.org/10.1371/journal.pone.0055418, 2013.
In the dry grassland investigated in this study the components of the soil CO2 efflux decreased at different rates under drought conditions. During drought the contribution made by the heterotrophic components was the highest and the rhizospheric component was the most sensitive to soil drying. According to our results, the heterotrophic component of soil respiration is the major contributor to the respiration activities during drought events.
In the dry grassland investigated in this study the components of the soil CO2 efflux decreased...