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Flux Towers Galore

Old and Not-So-Old Research Progress/Plans for Ankur Desai Penn State University, Department of Meteorology Cheas 2003 Meeting, Woodruff, WI, 29 June – 2 July. Flux Towers Galore. Sylvania Old-Growth Age: 0-350, mean around 100 Species: Hemlock-Maple-Birch LAI: 3.79 (hemlock), 4.06 (maple)

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Flux Towers Galore

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  1. Old and Not-So-OldResearch Progress/Plansfor Ankur DesaiPenn State University, Department of MeteorologyCheas 2003 Meeting, Woodruff, WI, 29 June – 2 July

  2. Flux Towers Galore Sylvania Old-Growth Age: 0-350, mean around 100 Species: Hemlock-Maple-Birch LAI: 3.79 (hemlock), 4.06 (maple) Established: 8/2001 Willow Creek Age: 66 yrs Species: Maple-Basswood-Ash Canopy height: 24.3 m LAI: 4.18 Established: 5/1998 Climate: northern continental mean temp around 4 degrees C 80-90 cm precip/year 100-300 cm snowfall/year

  3. 2002 Climatology

  4. Observed NEE

  5. Heterogeneous Site…

  6. Wacky Lakes and Bogs?

  7. Screening madness FOR 2002 Screen NEE Resp Psyn (gC/m2/yr) standard wind screen 16% -72.0 965.2 1037.2 no wind screen 0% -121.6 823.2 944.8 no winds from 30-90 degrees 8% -124.9 832.9 957.8 no SW winds 40% -260.3 580.4 840.7 SW winds only 60% -83.2 1009.6 1092.8 no N winds 45% -120.6 910.4 1031.0 no NW-SE winds 33% -140.0 871.5 1011.5 FOR Jun-Aug 2002 Screen Daily Night Noon (umol/m2/s) standard wind screen 16% -1.6 6.7 -12.0 no wind screen 0% -1.9 5.8 -11.8 no winds from 30-90 degrees 8% -1.9 5.8 -12.0 no SW winds 40% -2.8 3.8 -11.5 SW winds only 60% -1.4 6.9 -11.5 no N winds 45% -1.8 6.2 -11.7 no NW-SE winds 33% -1.8 6.0 -11.7

  8. 2002 NEE

  9. Diurnal NEE comparison

  10. 2002 Respiration

  11. 2002 Photosynthesis

  12. Component Fluxes

  13. Below canopy flux

  14. Research Hypotheses 1.) Net ecosystem uptake of carbon in an upper-Midwest undisturbed old-growth forest is smaller than a nearby second-growth forest, but it still a net carbon sink. This decrease is NEE is due to an linear increase with ecosystem respiration with stand age due to increased biomass and coarse woody debris and a leveling off of ecosystem net photosynthesis with stand age. Quantification of this hypothesis will allow for a rough approximation of the maximum potential for carbon storage of forests in the upper Midwest that follow a similar successional pathway. 2.) Both forest ecosystems have similar sensitivities in forest carbon uptake to climate variability. Verification of this claim will help explain regional scale interannual variability in carbon fluxes. 3.) Ecosystem scale CO2 flux depends directly on leaf and soil level component carbon and water fluxes, which change as forests age (i.e. stem respiration decreases, leaf light use efficiency decreases, coarse woody debris respiration increases with stand age). Testing this hypothesis will help determine how the physical processes behind carbon uptake change with stand age.

  15. Research Hypotheses 4.) Regional scale CO2 flux is a mosaic of ecosystem scale CO2 fluxes. Also, the regional scale flux can be modeled with process-based models driven by climatology and remote sensing. If so, then we could directly upscale from ecosystem to regional scale. 5.) Other forests outside the region exhibit similar magnitudes of carbon uptake change with age. Also, we can create a general model of how this change will occur. Testing this hypothesis will help evaluate to what extent we can generalize the results found at our study site to other locations and thus possibly understand how forest carbon uptake might change at the continental or global scale. These hypotheses promulgate pieces to the puzzle of understanding how carbon storage in forest ecosystems generally change as they age. The results from testing these hypotheses will provide a way to estimate an upper-bound (barring disturbance) of the ability of terrestrial ecosystems to store carbon. This information is pertinent to formulating proper regional, national and international public policy for carbon emissions and sequestration.

  16. Publications • Posters: • Ameriflux Science Meeting, Boulder, CO, October 22-23, 2002 • The Carbon Balance of Forest Biomes, Society for Experimental Biology, Southampton, UK, April 1-4, 2003 • North American Carbon Program PI meeting, Arlington, VA, May 12-14, 2003 • Papers: • Desai, E. Carey, B. Cook, K. Davis, in preparation, A year of carbon storage at an old-growth hemlock-hardwood forest • Future papers: • B. Cook, A. Desai, et al., Eyring model and soil respiration • A. Desai, B. Cook, E. Carey, K. Davis, et al., Sylvania to Willow Creek comparison • E. Carey, A. Desai, Component fluxes at Sylvania • E. Carey, A. Desai, Transpiration fluxes at Sylvania

  17. Future Plans Funding: Since 2002 – funded as research assistant by DOE (ends 12/03) (Renewal sent in March 2003 and approved) Have applied for NASA Earth System Science fellowship Plans: Submit first Sylvania paper in summer (August 2003) Complete regular fieldwork (June 2003, Oct 2003, Jan 2004) Comprehensive exam in August 2003 Become a father in September 2003 Ameriflux intercomparison, Sept 10-20 2003 Work on comparison paper in fall of 2003 Finish dissertation by spring 2005 Defend by summer 2005 Future jobs: congressional fellow, post-doc abroad, science research institution

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