New tool for CO 2 flux partitioning with soil chamber flux implementation as a solution for site in topographically complex terrain Šigut, L., Mammarella, I., Kolari, P., Dařenová, E., Novosadová, K., Pietras, J., Pokorný, R., Sedlák, P., Mauder, M.

Eddy covariance Fluxes of matter and energy in halfhour resolution Annual sum of NEE – the most important product Separation of NEE into GPP and R eco by simple models Fluxes of matter and energy in halfhour resolution Annual sum of NEE – the most important product Separation of NEE into GPP and R eco by simple models

Light response curve (LRC) Temperature response curve (TRC) NEE GPP R eco

MR05 (Reichstein et al., 2005) Nighttime based R eco estim.; temperature response curve (TRC) fitting GL10 (Lasslop et al., 2010) Daytime based R eco estim.; TRC + light response curve (LRC) fitting –only R eco temperature sensitivity from nighttime data Both of these are accesible online ( R script (here proposed new tool) Combined nighttime and daytime R eco estim.; TRC + LRC fitting

Iterative TRC and LRC fitting

Proper seasonality removal is really important – changing time window size according to data coverage – respiration sensitivity to temperature: 10 °C range – light response curve: PAR range meeting requirements (for alpha 150 µmol m -2 s -1, A max 500 µmol m -2 s -1 )

Basic assumptions Homogenous vegetation Flat terrain Homogenous vegetation Flat terrain Bílý Kříž Beskydy Mts., Czech republic (877 m a.s.l., avg T=6.7 ± 1.1 °C) Norway Spruce monoculture 13° slope – advection Complex windflows, decoupling Beskydy Mts., Czech republic (877 m a.s.l., avg T=6.7 ± 1.1 °C) Norway Spruce monoculture 13° slope – advection Complex windflows, decoupling Advection

Biotic CO 2 flux Biotic ≠ measured CO 2 flux Mainly nighttime problems –R eco affected u * -filtering – standard Cannot be used for the site Biotic ≠ measured CO 2 flux Mainly nighttime problems –R eco affected u * -filtering – standard Cannot be used for the site Guan et al. 2006

Not filtered u * -filtered NEP = GPP - R eco NPP = GPP - R A

Raich a Schlesinger, 1992: R soil = 40 – 80 % of R eco Kolari et al., 2009

Measurements only during growing season (May-Oct) 1)keep nighttime eddy covariance data outside GS Measurements only during growing season (May-Oct) 1)keep nighttime eddy covariance data outside GS

Measurements only during growing season (May-Oct) 2)use chamber based estimates outside of GS Measurements only during growing season (May-Oct) 2)use chamber based estimates outside of GS windfall the longest GS LAI increase

Seasonality removal should get more attention R script for flux partitioning produces defensible NEP Seasonality removal should get more attention R script for flux partitioning produces defensible NEP R script Complex site Single value of R soil /R eco ratio not valid for all years Lack of chamber measurement outside GS is probably causing R eco under- (1)/overestimation (2) in selected approaches Interanual changes in stand density, LAI and GS length explain the best the observed NEP pattern Single value of R soil /R eco ratio not valid for all years Lack of chamber measurement outside GS is probably causing R eco under- (1)/overestimation (2) in selected approaches Interanual changes in stand density, LAI and GS length explain the best the observed NEP pattern

University of Ostrava: OU SGS20/PřF/2014 Global Change Research Centre AS CR, v. v. i. CZ.1.05/1.1.00/ , CZ.1.07/2.4.00/ University of Helsinki MICMoR graduate programme Bionetwork University of Ostrava: OU SGS20/PřF/2014 Global Change Research Centre AS CR, v. v. i. CZ.1.05/1.1.00/ , CZ.1.07/2.4.00/ University of Helsinki MICMoR graduate programme Bionetwork

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