Regional Carbon Fluxes in WI:

1. Regional Carbon Fluxes in WI: Cheas IX, June 2006 Moving towards synthesis 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. 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

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

19. Some Numbers • NPP (gC m-2 yr-1): • FIA 553 (1996-2004 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!