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Innovative CO2 Flux Partitioning Tool for Sites in Complex Terrain

This study introduces a new tool for CO2 flux partitioning using soil chamber flux data, ideal for sites in topographically complex terrain. It focuses on separating net ecosystem exchange (NEE) into gross primary productivity (GPP) and ecosystem respiration (Reco) through simple models. By combining nighttime and daytime Reco estimates, and utilizing temperature and light response curves, the tool enhances flux estimation accuracy. Lessons learned highlight the importance of proper seasonality removal and adjusting time window sizes based on data coverage. The research emphasizes the significance of site complexity in ecosystem flux partitioning and proposes improvements for more reliable NEE estimation. 8 Relevant

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Innovative CO2 Flux Partitioning Tool for Sites in Complex Terrain

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  1. New tool for CO2 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.

  2. Introduction Eddy covariance • Fluxesofmatter and energy in halfhourresolution • Annual sum of NEE – the most importantproduct • Separationof NEE into GPP and Recoby simplemodels

  3. Simplemodels NEE Reco GPP • Light response curve (LRC) • Temperature response curve (TRC)

  4. Methods • MR05 (Reichstein et al., 2005) • NighttimebasedRecoestim.; temperature response curve (TRC) fitting • GL10 (Lasslop et al., 2010) • DaytimebasedRecoestim.; TRC + lightresponse curve(LRC) fitting • onlyRecotemperature sensitivity fromnighttime data • Bothof these are accesible online • (http://www.bgc-jena.mpg.de/~MDIwork/eddyproc) • R script (hereproposednewtool) • Combinednighttime and daytimeRecoestim.; TRC + LRC fitting

  5. Fine resolutionfitting Iterative TRC and LRC fitting

  6. Lessonslearned • Proper seasonalityremovalisreallyimportant • changingtimewindowsizeaccording to data coverage • respiration sensitivity to temperature: 10 °C range • light response curve: PAR range meeting requirements(foralpha 150 µmol m-2 s-1, Amax 500 µmol m-2 s-1)

  7. Complexsite Basic assumptions Advection • Homogenousvegetation • Flatterrain Bílý Kříž • Beskydy Mts., Czech republic(877 m a.s.l., avgT=6.7 ± 1.1 °C) • NorwaySprucemonoculture • 13° slope– advection • Complexwindflows, decoupling

  8. Estimationof NEP Biotic CO2 flux • Biotic ≠ measured CO2 flux • Mainlynighttimeproblems • Recoaffected • u*-filtering– standard • Cannotbeusedforthesite Guan et al. 2006

  9. Not filtered NEP = GPP - Reco NPP = GPP - RA u*-filtered

  10. Chambersupscaling ? Rsoil = % Reco Raicha Schlesinger, 1992: Rsoil = 40 – 80 % ofReco Kolari et al., 2009

  11. Measurementsonlyduringgrowingseason (May-Oct) • keepnighttimeeddycovariance data outside GS Rsoil = x%Reco

  12. Measurementsonlyduringgrowingseason (May-Oct) • use chamberbasedestimatesoutsideof GS windfall windfall Rsoil = x%Reco thelongest GS LAI increase

  13. Conclusion R script • Seasonalityremovalshouldget more attention • R scriptfor flux partitioningproducesdefensible NEP Complexsite • Single value of Rsoil/Reco ratio not valid for all years • Lack of chamber measurement outside GS is probably causing Recounder- (1)/overestimation (2) in selectedapproaches • Interanualchanges in standdensity, LAI and GS lengthexplainthebesttheobserved NEP pattern

  14. Acknowledgement • University of Ostrava: OU SGS20/PřF/2014 • GlobalChangeResearch Centre AS CR, v. v. i. CZ.1.05/1.1.00/02.0073, CZ.1.07/2.4.00/31.0056 • University ofHelsinki • MICMoRgraduateprogramme • Bionetwork

  15. Thankyouforyourattention

  16. Q & A

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