On the choice of the driving temperature for eddy-covariance carbon dioxide flux partitioning

Abstract. Networks that merge and harmonise eddy-covariance measurements from many different parts of the world have become an important observational resource for ecosystem science. Empirical algorithms have been developed which combine direct observations of the net ecosystem exchange of carbon dioxide with simple empirical models to disentangle photosynthetic (GPP) and respiratory fluxes (Reco). The increasing use of these estimates for the analysis of climate sensitivities, model evaluation and calibration demands a thorough understanding of assumptions in the analysis process and the resulting uncertainties of the partitioned fluxes. The semi-empirical models used in flux partitioning algorithms require temperature observations as input, but as respiration takes place in many parts of an ecosystem, it is unclear which temperature input – air, surface, bole, or soil at a specific depth – should be used. This choice is a source of uncertainty and potential biases. In this study, we analysed the correlation between different temperature observations and nighttime NEE (which equals nighttime respiration) across FLUXNET sites to understand the potential of the different temperature observations as input for the flux partitioning model. We found that the differences in the correlation between different temperature data streams and nighttime NEE are small and depend on the selection of sites. We investigated the effects of the choice of the temperature data by running two flux partitioning algorithms with air and soil temperature. We found the time lag (phase shift) between air and soil temperatures explains the differences in the GPP and Reco estimates when using either air or soil temperatures for flux partitioning. The impact of the source of temperature data on other derived ecosystem parameters was estimated, and the strongest impact was found for the temperature sensitivity. Overall, this study suggests that the choice between soil or air temperature must be made on site-by-site basis by analysing the correlation between temperature and nighttime NEE. We recommend using an ensemble of estimates based on different temperature observations to account for the uncertainty due to the choice of temperature and to assure the robustness of the temporal patterns of the derived variables.

[1]  Andrew E. Suyker,et al.  Annual carbon dioxide exchange in irrigated and rainfed maize-based agroecosystems , 2005 .

[2]  Y A N E R Y A N *, B I N Z H A O,et al.  Closing the carbon budget of estuarine wetlands with tower-based measurements and MODIS time series , 2008 .

[3]  T. Meyers,et al.  An assessment of storage terms in the surface energy balance of maize and soybean , 2004 .

[4]  B. Bond,et al.  Interpreting diel hysteresis between soil respiration and temperature , 2009 .

[5]  K. Davis,et al.  Carbon exchange and venting anomalies in an upland deciduous forest in northern Wisconsin, USA , 2004 .

[6]  W. Cropper,et al.  Carbon exchange of a mature, naturally regenerated pine forest in north Florida , 2008 .

[7]  W. Knorr,et al.  Inversion of terrestrial ecosystem model parameter values against eddy covariance measurements by Monte Carlo sampling , 2005 .

[8]  Olaf Kolle,et al.  Large carbon uptake by an unmanaged 250-year-old deciduous forest in Central Germany , 2002 .

[9]  S. Seneviratne,et al.  Response to Comment on “Global Convergence in the Temperature Sensitivity of Respiration at Ecosystem Level” , 2011, Science.

[10]  R. O N A L,et al.  The annual cycles of CO 2 and H 2 O exchange over a northern mixed forest as observed from a very tall tower , 2003 .

[11]  Markus Reichstein,et al.  Biosphere-atmosphere exchange of CO2 in relation to climate: a cross-biome analysis across multiple time scales , 2009 .

[12]  Hans Peter Schmid,et al.  Measurements of CO 2 and energy fluxes over a mixed hardwood forest in the mid-western United States , 2000 .

[13]  Riccardo Valentini,et al.  Annual variation in soil respiration and its components in a coppice oak forest in Central Italy , 2002 .

[14]  D. Guyon,et al.  Quality analysis applied on eddy covariance measurements at complex forest sites using footprint modelling , 2005 .

[15]  M. S. Moran,et al.  Variability of emissivity and surface temperature over a sparsely vegetated surface , 1994 .

[16]  Ü. Rannik,et al.  Productivity overshadows temperature in determining soil and ecosystem respiration across European forests , 2001 .

[17]  A. Arneth,et al.  Separation of net ecosystem exchange into assimilation and respiration using a light response curve approach: critical issues and global evaluation , 2010 .

[18]  Mark A. Sutton,et al.  Partitioning European grassland net ecosystem CO2 exchange into gross primary productivity and ecosystem respiration using light response function analysis , 2007 .

[19]  Lawrence B. Flanagan,et al.  Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland , 2002 .

[20]  T. Vesala,et al.  On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm , 2005 .

[21]  K. Davis,et al.  Component and whole-system respiration fluxes in northern deciduous forests. , 2004, Tree physiology.

[22]  J. Peñuelas,et al.  Remote estimation of carbon dioxide uptake by a Mediterranean forest , 2008 .

[23]  Ryuichi Hirata,et al.  CO2 and water vapor exchange of a larch forest in northern Japan , 2003 .

[24]  T. Vesala,et al.  Biophysical controls on CO2 fluxes of three Northern forests based on long-term eddy covariance data , 2008 .

[25]  T. Andrew Black,et al.  Carbon dioxide fluxes in coastal Douglas-fir stands at different stages of development after clearcut harvesting , 2006 .

[26]  T. Black,et al.  Carbon sequestration in boreal jack pine stands following harvesting , 2009 .

[27]  J. Monteith,et al.  Principles of Environmental Physics , 2014 .

[28]  Tuomas Laurila,et al.  CO2 exchange of a sedge fen in southern Finland-the impact of a drought period , 2007 .

[29]  P. Ciais,et al.  Influence of spring and autumn phenological transitions on forest ecosystem productivity , 2010, Philosophical Transactions of the Royal Society B: Biological Sciences.

[30]  Eric Ceschia,et al.  The carbon balance of a young Beech forest , 2000 .

[31]  S. Seneviratne,et al.  Contrasting response of European forest and grassland energy exchange to heatwaves , 2010 .

[32]  Wenjun Chen,et al.  Increased carbon sequestration by a boreal deciduous forest in years with a warm spring , 2000 .

[33]  Zisheng Xing,et al.  Total and component carbon fluxes of a Scots pine ecosystem from chamber measurements and eddy covariance. , 2007, Annals of botany.

[34]  Niels Otto Jensen,et al.  Increasing net CO2 uptake by a Danish beech forest during the period from 1996 to 2009 , 2011 .

[35]  H. Akaike,et al.  Information Theory and an Extension of the Maximum Likelihood Principle , 1973 .

[36]  W. Oechel,et al.  Effects of Elevated Atmospheric CO2 on Soil Microbial Biomass, Activity, and Diversity in a Chaparral Ecosystem , 2005, Applied and Environmental Microbiology.

[37]  David R. Anderson,et al.  Null Hypothesis Testing: Problems, Prevalence, and an Alternative , 2000 .

[38]  T. Vesala,et al.  Towards a standardized processing of Net Ecosystem Exchange measured with eddy covariance technique: algorithms and uncertainty estimation , 2006 .

[39]  M. Bahn,et al.  On the ‘temperature sensitivity’ of soil respiration: Can we use the immeasurable to predict the unknown? , 2010, Soil biology & biochemistry.

[40]  R. Leuning,et al.  Application of an alternative method to derive reliable estimates of nighttime respiration from eddy covariance measurements in moderately complex topography , 2008 .

[41]  Dennis D. Baldocchi,et al.  Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California , 2004 .

[42]  Hans Peter Schmid,et al.  Measurements of CO2 and energy fluxes over a mixed hardwood forest in the mid-western United States , 2000 .

[43]  Bruce K. Wylie,et al.  Integration of CO 2 flux and remotely-sensed data for primary production and ecosystem respiration analyses in the Northern Great Plains: potential for quantitative spatial extrapolation , 2005 .

[44]  Kenneth J. Davis,et al.  The annual cycles of CO2 and H2O exchange over a northern mixed forest as observed from a very tall tower , 2003 .

[45]  D. Hillel.  Introduction to environmental soil physics , 1982 .

[46]  Corinna Rebmann,et al.  Treatment and assessment of the CO2-exchange at a complex forest site in Thuringia, Germany , 2010 .

[47]  Marco Bindi,et al.  Modelling carbon budget of Mediterranean forests using ground and remote sensing measurements , 2005 .

[48]  Thomas Foken,et al.  Quality control of CarboEurope flux data – Part 2: Inter-comparison of eddy-covariance software , 2007 .

[49]  Andrej Varlagin,et al.  Modeling carbon dynamics in two adjacent spruce forests with different soil conditions in Russia , 2008 .

[50]  Per Ambus,et al.  Field measurements of atmosphere-biosphere interactions in a Danish beech forest , 2003 .

[51]  L. Weihermüller,et al.  Comment on “Global Convergence in the Temperature Sensitivity of Respiration at Ecosystem Level” , 2011, Science.

[52]  S. Seneviratne,et al.  Global Convergence in the Temperature Sensitivity of Respiration at Ecosystem Level , 2010, Science.

[53]  F. Woodward,et al.  Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate , 2010, Science.

[54]  T. Foken,et al.  Documentation of reference data for the experimental areas of the Bayreuth Centre for Ecology and Environmental Research (BayCEER) at the Waldstein site , 2007 .

[55]  B. Kruijt,et al.  Assessing the uncertainty of estimated annual totals of net ecosystem productivity: A practical approach applied to a mid latitude temperate pine forest , 2011 .

[56]  T. Vesala,et al.  Quality control of CarboEurope flux data , 2007 .

[57]  János Balogh,et al.  The carbon budget of semi-arid grassland in a wet and a dry year in Hungary , 2007 .

[58]  Olaf Kolle,et al.  Seasonal variation in energy fluxes and carbon dioxide exchange for a broad‐leaved semi‐arid savanna (Mopane woodland) in Southern Africa , 2004 .

[59]  Jiquan Chen,et al.  Closing the carbon budget of estuarine wetlands with tower‐based measurements and MODIS time series , 2008 .

[60]  Eero Nikinmaa,et al.  CO2 exchange and component CO2 fluxes of a boreal Scots pine forest , 2009 .

[61]  M. Aubinet,et al.  Long term carbon dioxide exchange above a mixed forest in the Belgian Ardennes , 2001 .

[62]  Osvaldo L. L. Moraes,et al.  Land‐use change effects on local energy, water, and carbon balances in an Amazonian agricultural field , 2004 .

[63]  G. Bohrer,et al.  Disturbance and the resilience of coupled carbon and nitrogen cycling in a north temperate forest , 2011 .

[64]  Robert Clement,et al.  A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies. , 2006, Tree physiology.

[65]  Markus Reichstein,et al.  Modeling temporal and large‐scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices , 2003 .

[66]  W. Cropper,et al.  Controls on carbon dynamics by ecosystem structure and climate for southeastern U.S. slash pine plantations , 2012 .

[67]  Josep Peñuelas,et al.  Remote estimation of carbon dioxide uptake by a Mediterranean forest , 2008 .

[68]  Christopher J. Kucharik,et al.  Effects of logging on carbon dynamics of a jack pine forest in Saskatchewan, Canada , 2004 .

[69]  W. Oechel,et al.  Seasonality of ecosystem respiration and gross primary production as derived from FLUXNET measurements , 2001 .

[70]  M. A. Arain,et al.  Net ecosystem production in a temperate pine plantation in southeastern Canada , 2005 .

[71]  Marc Aubinet,et al.  Annual net ecosystem carbon exchange by a sugar beet crop , 2006 .

[72]  Tiina Markkanen,et al.  Air temperature triggers the recovery of evergreen boreal forest photosynthesis in spring , 2003 .

[73]  Lawrence B. Flanagan,et al.  Environmental control of net ecosystem CO2 exchange in a treed, moderately rich fen in northern Alberta , 2006 .

[74]  Steven W. Running,et al.  A daily soil temperature model based on air temperature and precipitation for continental applications , 1993 .

[75]  P. Anthoni,et al.  Forest and agricultural land‐use‐dependent CO2 exchange in Thuringia, Germany , 2004 .

[76]  Mark Heuer,et al.  Direct and indirect effects of atmospheric conditions and soil moisture on surface energy partitioning revealed by a prolonged drought at a temperate forest site , 2006 .

[77]  W. Oechel,et al.  Environmental controls over carbon dioxide and water vapor exchange of terrestrial vegetation , 2002 .

[78]  Markus Reichstein,et al.  Cross-site evaluation of eddy covariance GPP and RE decomposition techniques , 2008 .

[79]  Christian Bernhofer,et al.  Land use regulates carbon budgets in eastern Germany: From NEE to NBP , 2010 .

[80]  R. Valentini,et al.  Soil respiration in a Mediterranean oak forest at different developmental stages after coppicing , 2006 .

[81]  T. A. Black,et al.  Comparison of carbon dioxide fluxes over three boreal black spruce forests in Canada , 2007 .

[82]  R. Miller,et al.  Changes in Soil Microbial Community Structure in a Tallgrass Prairie Chronosequence , 2005 .

[83]  K. Wilson,et al.  Comparing independent estimates of carbon dioxide exchange over 5 years at a deciduous forest in the southeastern , 2001 .

[84]  J. Lloyd,et al.  On the temperature dependence of soil respiration , 1994 .

[85]  David P. Billesbach,et al.  Spatiotemporal Variations in Growing Season Exchanges of CO2, H2O, and Sensible Heat in Agricultural Fields of the Southern Great Plains , 2007 .

[86]  Markus Reichstein,et al.  Improving canopy processes in the Community Land Model version 4 (CLM4) using global flux fields empirically inferred from FLUXNET data , 2011 .

[87]  H. Mayer,et al.  CO2 fluxes of a Scots pine forest growing in the warm and dry southern upper Rhine plain, SW Germany , 2006, European Journal of Forest Research.

[88]  Miikka Dal Maso,et al.  Long-term measurements of surface fluxes above a Scots pine forest in Hyytiälä, southern Finland, 1996-2001 , 2003 .

[89]  Makoto Saito,et al.  Seasonal variation of carbon dioxide exchange in rice paddy field in Japan , 2005 .

[90]  Biophysical controls on CO2 fluxes of three Northern forests based on long-term eddy covariance data , 2008 .

[91]  J. Tenhunen,et al.  Inverse modeling of seasonal drought effects on canopy CO2/H2O exchange in three Mediterranean ecosystems , 2003 .

[92]  S. Wofsy,et al.  Factors controlling CO2 exchange on timescales from hourly to decadal at Harvard Forest , 2007 .

[93]  Michael Bahn,et al.  Seasonal and inter-annual variability of the net ecosystem CO2 exchange of a temperate mountain grassland: effects of climate and management. , 2008, Journal of geophysical research. Atmospheres : JGR.

[94]  Christian Bernhofer,et al.  A decade of carbon, water and energy flux measurements of an old spruce forest at the Anchor Station Tharandt , 2007 .

[95]  B. Law,et al.  Random and systematic CO2 flux sampling errors for tower measurements over forests in the convective boundary layer , 2009 .

[96]  Steve Frolking,et al.  Interannual variability in the peatland‐atmosphere carbon dioxide exchange at an ombrotrophic bog , 2003 .

[97]  Hank A. Margolis,et al.  Ecosystem-level CO2 fluxes from a boreal cutover in eastern Canada before and after scarification , 2006 .

[98]  R. Monson,et al.  Carbon sequestration in a high‐elevation, subalpine forest , 2001 .

[99]  Thomas L. Powell,et al.  Environmental controls over net ecosystem carbon exchange of scrub oak in central Florida , 2006 .