Dynamics of CO2 fluxes from boreal peatlands [Elektronische Ressource] / Julia Schneider

Julia

Sujets

• Biologie

Informations

• Publié par: ernst-moritz-arndt-universitat_greifswald
• Publié le: 01 janvier 2011
• Nombre de lectures: 86
• Poids de l'ouvrage: 4 Mo

Extrait

Dynamics of CO fluxes from boreal peatlands 2





I n a u g u r a l d i s s e r t a t i o n

zur

Erlangung des akademischen Grades

doctor rerum naturalium (Dr. rer. nat.)

an der Mathematisch-Naturwissenschaftlichen Fakultät

der

Ernst-Moritz-Arndt-Universität Greifswald


vorgelegt von

Julia Schneider

geboren am 03.11.1979

in Tarko-Sale (Russische Föderation)








Greifswald, 05. Oktober 2010

































Dekan:

Prof. Dr. Klaus Fesser

1. Gutachter :

Prof. Dr. Martin Wilmking

2. Gutachter:

Prof. Dr. Eva-Maria Pfeiffer

Tag der Promotion:

02.05.2011 in Greifswald
Content

Abstract……………………………………………………………...………………….....….V
Zusammenfassung……………………………….……………………………………...…..VII


1. Introduction ......................................................................................................................... 1

1.1 Present understanding and methods .................................................................................... 1
1.2 Objectives of this dissertation .............................................................................................4
1.3 Author’s contribution to the individual papers ................................................................... 5
1.4 References ........................................................................................................................... 7

2. Overestimation of CO respiration fluxes by the closed chamber method in low-2
turbulence nighttime conditions ........................................................................................... 11

2.1 Abstract ............................................................................................................................. 11
2.2 Introduction ....................................................................................................................... 12
2.3 Methods............................................................................................................................. 13
2.3.2 Study site 13
2.3.2 Experimental setup................................................................................................ 14
2.3.3 CO concentration profile measurements.............................................................. 14 2
2.3.4 CO flux measurements......................................................................................... 14 2
2.3.5 Screening and modelling of CO respiration fluxes.............................................. 15 2
2.4 Results........... 16
2.4.1 CO concentration profile measurements 16 2
2.4.2 CO flux measurements 17 2
2.5 Discussion ......................................................................................................................... 23
2.6 References........ 28

3. Carbon dioxide dynamics of a boreal peatland over a complete growing season,
Komi Republic, NW Russia.................................................................................................. 33

3.1 Abstract ............................................................................................................................. 33
3.2 Introduction ....................................................................................................................... 34
3.3 Methods............................................................................................................................. 35
3.3.1 Study site 35
3.3.2 Experimental setup................................................................................................ 38
3.3.3 CO flux measurements......................................................................................... 39 2
3.3.4 Screening and modelling of CO fluxes................................................................ 40 2
3.4 Results........... 42
3.4.1 Weather, soil conditions and vegetation development during the period of
observation ............................................................................................................ 42
3.4.2 Measured CO fluxes ............................................................................................ 44 2
3.4.3 Environmental controls on NEE, R and GPP and modelling carbon balance 48 eco ......
I3.5 Discussion ......................................................................................................................... 50
3.5.1 Within microform variability in CO fluxes ......................................................... 50 2
3.5.2 Variability in CO fluxes between microform types............................................. 52 2
3.5.3 Variability in CO fluxes between ombrogenous and minerogenous parts of the 2
peatland 55
3.5.4 Seasonal cycle of CO fluxes ................................................................................ 55 2
3.5.5 Environmental controls and model performance .................................................. 56
3.5.6 Spatial upscaling ................................................................................................... 59
3.6 Summary and conclusions................................................................................................. 61
3.7 References........ 62
3.8 Appendix: Model parameters, coefficients of determination, root mean square error ..... 65

4. Boreal peatland net ecosystem CO exchange – an integrative comparison between 2
measured fluxes and LPJ-GUESS model output ............................................................... 71

4.1 Abstract ............................................................................................................................. 71
4.2 Introduction ....................................................................................................................... 72
4.3 Methods............................................................................................................................. 73
4.3.1 Study site 73
4.3.2 Experimental setup and flux calculations.............................................................. 74
4.3.3 Empirical time series modelling............................................................................ 76
4.3.4 Determination of microform coverage and remote sensing .................................. 77
4.3.5 Footprint modelling............................................................................................... 80
4.3.6 Upscaling of CO fluxes from plot scale to ecosystem scale................................ 81 2
4.3.7 LPJ-GUESS model................................................................................................ 82
4.3.8 Uncertainty analysis .............................................................................................. 85
4.3.9 Evaluation of the model performance ................................................................... 85
4.4 Results ............................................................................................................................... 86
4.4.1 Variability of NEE fluxes at plot and ecosystem scales........................................ 86
4.4.2 Microform distribution at the intensive study site ................................................ 88
4.4.3 Footprint analysis .................................................................................................. 88
4.4.4 Comparison of CO fluxes observed from chamber and eddy covariance 2
measurements........................................................................................................ 89
4.4.5 Evaluation of LPJ-GUESS model output.............................................................. 92
4.5 Discussion ......................................................................................................................... 95
4.5.1. Mismatch between NEE fluxes upscaled from chamber and observed from eddy
covariance measurements...................................................................................... 95
4.5.2 Biases in land cover classification and upscaling ................................................. 96
4.5.3. Sources of uncertainty in model simulations ....................................................... 98
4.5.4. Comparison to other peatland studies and forest flux estimates .......................... 98
4.6 Summary and conclusions................................................................................................. 99
4.7 References ....................................................................................................................... 101
II5. CO flux determination by closed chamber methods can be seriously biased by 2
inappropriate application of linear regression ................................................................. 107

5.1 Abstract .....................................................................................................................