Sylvania Wilderness / Helen Lake Flux Tower

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Location:  Tower location (GPS, taken in 8/2001): 46 14' 31.26'' N, 89 20' 51.54'' W  (click here for maps)
The site is within the 8,500 hectare Sylvania Tract of the Ottawa National Forest, one of only two remaining large tracts of old growth forest in the Great Lakes region.  The tower is adjacent to the Sylvania Wilderness Area. 

Elevation:  At tower base: 500 m / 1650 ft above mean sea level (GPS altitude, 8/2001)

Annual average precipitation/snowfall (Marquette, MI, 1961-1990):  89.6 / 320.5 cm (snowfall is less near site due to diminished lake effect)

Annual average temperature (Marquette, MI, 1961-1990):  3.9C

Stand age:  Trees range in age from current year regeneration to > 350 years old.  Large, old trees make up a significant component of the canopy.

Species composition
:  Dominant species present on the site are basswood (Tilia americana), eastern hemlock (Tsuga canadensis), ironwood (Ostrya virginiana), sugar maple (Acer saccharum), and yellow birch (Betula alleghaniensis).  Only limited, selected logging of white pine has occurred near lake shores.  The site pairs well with Willow Creek, WI as a successional stage comparison because the presettlement vegetation on both sites was the same.

Average canopy height:  26-27 m, tower height is 37 m

Average leaf area index (LAI): 4.06 in sugar maple-dominated patches, 3.79 in hemlock-dominated patches

Research objectives: 1.) Characterize the net ecosystem exchange (NEE) of carbon of an undisturbed old-growth forest. 2.) Quantify the relative response of old-growth versus regrowing forests to climate variability and climate change. 3.) Determine to what degree component carbon fluxes differ between early and late successional stands thereby examining the role of stand age as a determining factor of atmospheric CO2 storage.

Funding Agency: Department of Energy, Terrestrial Carbon Processes

Established:  August 2001

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PHOTOGRAPHS (Click here to see additional photos! )

37 m tower
CO2 profiling system
Equipment enclosure

Forest canopy viewed from top of tower
Understory viewed from base of tower

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    Rohn 45G tower (120 ft)
    (4) canopy access scaffolding towers (40-70 ft)

CSI CR23X datalogger, 4 Mb extended memory
    CSI CR10X datalogger, 2 Mb extended memory (2)
    CSI AM416 multiplexers
    LI-COR 6262 (CO2/H2O fluxes) and 6252 (CO2 profile) and 6400 (respiration/photosynthesis measurements)
 KNF UN89DCB-12V brushless DC diaphragm pumps, " (od) Bev-a-Line IX, Teflon, or Dekabon 1300 tubing, and Gelman Acro 50 teflon inlet filters
   High precision CO2 profiler (see Peter Bakwin et al., 1998, Tellus 50B:401-415)
    CSI CSAT3 3D Sonic anemometer
    Campbell / Vaisala HMP45C temperature/humidity probes
    Vaisala PTB101B analog barometer
    Kipp & Zonen NR-LITE net radiometer (above canopy)

    CSI model 237 leaf wetness sensor
    Type T thermocouples (soil/tree temperatures; air temperatures from 0.25 to 2 m)
    CSI 10TCRXTCR Thermocouple reference thermistor
    REBS HFT-3 soil heat flux plate
    CSI CS615 Soil water content reflectometer probes
    Kipp and Zonen Quantum sensors (PAR)
    RM Young model 03002 wind sentries
    Texas Electronics 6" tripping bucket rain gauge with CSI CS705 snowfall adapter

    CSI Rad-Haul and SC532 interfaces
    Micron PC and Iomega 250 Mb Zip drive, running Windows 98, Symantec PC Anywhere, Campbell PC 208W
    Campbell COM100 Cellular telephone package: Motorola Analog Phone and Transceiver connected to 56K modem
    Yagi 12 db antenna

200 Amp AC Utility power, APC Line Conditioner, 20 Amp DC power supply

Sampling Frequencies:
    0.1 second - eddy covariance measurements (wind speed/direction, CO2, H2O)
    1 second - radiation, air temperature, H2O mixing ratio, barometric pressure, canopy PAR, net rad, wind speed/direction
                    air temperature/humidity, leaf wetness (all are output with 1 minute average)
    10 minutes - air & soil temperatures, soil moisture, soil heat flux, total precipitation in interval
    21 minutes - interval between profile CO2 measurements for any level

Standards and Calibration:
    CO2standards - 330, 440, 550 ppm CO2 in dry air (calibrated using 330 and 550 ppm NOAA primary standards).
    CO2 mixing ratio - LI-6252 zeroed every 42 minutes, calibrated with 3 standards every 4 hours.
    CO2 and H2O flux - LI-6262 continuously calibrated with LI-6251 and Vaisala humidity measurement.

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VIEW PLOTS (You will need Adobe Acrobat and/or Ghost View to view these plots)

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CONTACTS (click on names for detailed contact information)

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If you have comments or questions about this page, please email Ankur Desai