ADVEX overview paper summary: vertical advection

1. ADVEX overview paper summary: vertical advection positive during the night zero Zero mean but large scatter

2. ADVEX overview paper summary: horizontal advection Positive during the nightslightly negative during the day, trunk space Weak positive advection during the nighttrunk space Large negative advection during the nightlarge scattercrown space

3. Direction of future scientific work ADVEX field campaigns Typologymechanisms at workAubinet (2007) Model simulations(CFD, LES)in cooperation with INRA Exploring the “noise” Development of a robust correction scheme of EC-fluxes for advectionConference on advectionJuly 2008 in Belgium

4. Spatial distribution of NBP of grasslands in Europe (data upscaling) Assuming a management similar to mean site management

5. How large is the grassland C sink?

6. Synthesis paper • First draft will be discussed during grassland & wetland session • Conclusions: grasslands are a strong C sink (ca. same as forests) • Trade-off by N2O and CH4 is relatively low (30 % reduction in NBP) • Indirect emissions (e.g. indirect N2O, off site forage digestion) further reduce NBP by 15 % • The C sink can be managed, but it is highly vulnerable to drought events and, hence, to climate change.

7. Uncertainty on Anthropogenic Carbon Emissions Up to 250 ppm Vulnerability of the Carbon Cycle in the 21st century Uncertainty of the Biospheric-Carbon-Climate Feedback Up to 200 ppm IPCC SRES 2000; Friedlingstein et al. 2006 Slide courtesy of Pep Canadell, GCP

8. Uncertainty in cropland & grassland SOC stock changes due to climate, NPP & technology change (HadCM3-A2) Minimum Climate Only Climate & NPP Climate & NPP & Tech Maximum J.U. Smith et al. (2005)

9. Organic soil restoration vs. mineral soil sequestration Data from: Smith et al. (2007a)

10. Part A - Eight different forests T = -0.9°C P = 305 mmBirch T = -1.0°C P = 429 mmPine T = 3.4°C P = 738 mmLarch T = 1.2°C P = 523 mmSpruce T = 3.0°C P = 700 mmPine T = 5.5°C P = 527 mmPine/Spruce T = 8.3°C P = 730 mmBeech

12. What about correlation with latitude?(reminding about Valentini et al., 2000) .and after normalizing for LAI-dependence

13. .and after normalizing for LAI-dependence

14. After normalization for the LAI-dependency - no correlationwith latitude!

15. Surprising finding by Annikki M. Measured GPP: eddy covariance GPP, mean of yearly totals Slope ≈ 0.45 ΦTOT: fAPAR times growing season sum of above-canopy PAR, mean of yearly totals • Estimates of site-specific LUE parameters β: • for the European sites taken from the fitting of the variable-LUE model • for the Ameriflux sites estimated with linear regression

16. Magnani et al (2007) Nature 447, 848 Not a temperature effect! 1g N→210gC

17. Tree rings show that carbon continues to accumulate, but often in an erratic manner! Scots pine, Glen Affric (Scotland), data of Teri Fish & Rob Wilson See Martinez-Vilalta, Vanderklein, Mencuccini (2007) on age-related decline; Ryan et al, (2006), Mencuccini & Grace (1996), Koch et al (2004).

18. Biomass accumulation in deciduous (●) and needle leaved (●) species

19. Long term period Forest C stock change (NBP) 2000 -2060