1. Regional Carbon Fluxes in WI:
Moving towards synthesis
Cheas IX, June 2006
Ankur R. Desai
Pennsylvania State University, Dept. of Meteorology
National Center for Atmospheric Research, Advanced Study Program
University of Wisconsin, Atmospheric & Oceanic Sciences Dept.

2. What is the regional carbon flux? Do we have to study its ursprache?
Question
One of several overarching ChEAS questions is:
What is the regional carbon flux?
Do we have to study its ursprache?

3. Pardon? WHAT -> define? quantify? explain?
IS -> present? past? future?
THE -> only one answer?
REGIONAL -> scale?
CARBON -> CO2, CH4, VOC?
FLUX? -> Vertical, horizontal, NBP?

4. Approaches Biometric / FIA Ecophysiological
Tall tower + footprint models
Stand scale eddy covariance towers
Tall tower ABL budgets
Multi-tower mesoscale inversion
Remote sensing (MODIS, LiDAR)
Modeling (ED, SiB, Biome-BGC)

5. A Bit About ED
Ensemble-average canopy gap model (Moorcroft et al., 2001; Albani et al., in press; Desai et al, submitted)
Conditioned on stand age and plant height (modifies light environment)
Multiple competing plants
Disturbance, mortality, harvest, reproduction control dynamics
Traditional soil/leaf biogeochemistry

6. A Bit About ED For ChEAS: 40 km radius of WLEF Forcing:
Pre-European settlement vegetation
Ecophysiological and allometric growth/respiration parameters
Long-term climate data
Forest harvest statistics
FIA to tune forest structure and params.
3 “grid cells” / subregions

7. Mesic Upland / N. Hardwoods Xeric Upland / Mixed conifer
ED MODEL PFTS
Mesic Upland / N. Hardwoods GR
Grass AS
Aspen BI
Birch SM
Sugar maple/basswood HE
Hemlock/Spruce
Xeric Upland / Mixed conifer
Shrub/Pine Barren JP
Jack Pine RP
Red Pine WP
White Pine/Fir RM
Red maple/Oak/Ash
Lowland / Wetland
Meadow grass AW
Alder/Willow shrub TM
Tamarack CE
Cedar BS
Black spruce

8. What Have We Learned When you’re up you’re up
When you’re down you’re down
And when you’re only halfway up, you’re neither up nor down
Puzzling results when comparing up-scaled estimates from one approach to another at a larger scale
You’re asking for trouble if you try to measure something more than once or in more than one way

9. What Have We Learned Stand age and species matter
Within site IAV < Across-site variability

10. What Have We Learned
Climate explains much of interannual variability of CO2 flux
We’re doing a better job at modeling it

11. What Have We Learned
But it’s harder to model indiv. stands

12. What Have We Learned
Over the long term, forest dynamics matter

13. What Have We Learned
Scale matters

14. What Have We Learned
Tree biophysics matter

15. What Have We Learned
Animals and pests matter

16. What Have We Learned
People matter

17. What Have We Learned
There’s a lot of things to worry about when answering “What is the regional carbon flux?”
We’re making good progress in spite of that
Starting to put together some of our top-down and bottom-up flux estimates
Need your help

18. Some Numbers NEE, several methods (gC m-2 yr-1)
better in Jun-Aug than all year
LEF
tall tower
Decomp.
Multi-site ED
Bakwin,
2004
Helliker,
Year
2003
2000
1997
Jun-Aug
-76
-149
-124
-258
-298
-177
-140
-174
Annual 80 95 44
-119
N/A
-143 77
-40

19. Some Numbers NPP (gC m-2 yr-1):
FIA 553 ( biomass increment) – litter (~100)
MODIS NPP (MOD17) 2002: ~600
Ahl et al, RSOE, 05 (ATLAS 15 m): 403
ED model: 423

20. Moving Toward Synthesis?
Maybe
More observations, more models, more processes
Will it help?
When is it enough?
What’s the next step?
Working on paper this summer at PSU on regional synthesis

21. Moving Toward Cuteness!