Old and Not-So-OldResearch Progress/Plans

for Ankur DesaiPenn State University, Department of Meteorology

Cheas 2003 Meeting, Woodruff, WI, 29 June – 2 July

Flux Towers GaloreSylvania Old-GrowthAge: 0-350, mean around 100Species: Hemlock-Maple-BirchLAI: 3.79 (hemlock), 4.06 (maple)Established: 8/2001

Willow CreekAge: 66 yrsSpecies: Maple-Basswood-AshCanopy height: 24.3 mLAI: 4.18Established: 5/1998

Climate: northern continentalmean temp around 4 degrees C80-90 cm precip/year100-300 cm snowfall/year

2002 Climatology

Observed NEE

Heterogeneous Site…

Wacky Lakes and Bogs?

Screening madnessFOR 2002 Screen NEE Resp Psyn (gC/m2/yr)

standard wind screen 16% -72.0 965.2 1037.2no wind screen 0% -121.6 823.2 944.8no winds from 30-90 degrees 8% -124.9 832.9 957.8no SW winds 40% -260.3 580.4 840.7SW winds only 60% -83.2 1009.6 1092.8no N winds 45% -120.6 910.4 1031.0no 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 -12.0no wind screen 0% -1.9 5.8 -11.8no winds from 30-90 degrees 8% -1.9 5.8 -12.0no SW winds 40% -2.8 3.8 -11.5SW winds only 60% -1.4 6.9 -11.5no N winds 45% -1.8 6.2 -11.7no NW-SE winds 33% -1.8 6.0 -11.7

2002 NEE

Diurnal NEE comparison

2002 Respiration

2002 Photosynthesis

Component Fluxes

Below canopy flux

Below canopy flux (preliminary)

0

1

2

3

4

5

6

7

178 178.5 179 179.5 180

2003 DOY

CO

2 f

lux

um

ol/

m2

/s

Research Hypotheses1.) 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.

Research Hypotheses4.) 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.

PublicationsPosters: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:A. 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 respirationA. Desai, B. Cook, E. Carey, K. Davis, et al., Sylvania to Willow

Creek comparisonE. Carey, A. Desai, Component fluxes at SylvaniaE. Carey, A. Desai, Transpiration fluxes at Sylvania

Future PlansFunding:

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 2003Become a father in September 2003Ameriflux intercomparison, Sept 10-20 2003Work on comparison paper in fall of 2003Finish dissertation by spring 2005Defend by summer 2005Future jobs: congressional fellow, post-doc abroad, science

research institution