University of Michigan Biological Station
The ecological research site for the UMBS Forest Carbon Cycle Research Program is located at the University of Michigan Biological Station (UMBS) in northern lower Michigan, USA. The research is centered around two meteorological (eddy covariance) towers that are part of the AmeriFlux network: a long-term observation tower and a tower within a disturbed area installed as part of the Forest Accelerated Succession ExperimenT (FASET experiment). For more information on the UMBS area, visit the UMBS research website.
UMBS AmeriFlux Towers
There are two meteorological towers at UMBS that are part of the UMBS Forest Carbon Cycle Research Program.
UMBS AmeriFlux Tower (US-UMB)
elevation 234 m amsl
A 46-m, self-supporting tower with associated lab building, power, and communication lines was completed in June, 1998. At the end of June and in July 1998 the instrument booms, data loggers, communication and gas-flow lines, and the eddy correlation and radiation sensors were installed on the two main observation levels of the tower (46 m and 34 m, see the schematic representation of the tower set-up, below). The flow control system was installed in September and data collection on the top level started on September 22, 1998. The profile measurements of mean temperature, humidity and CO2 concentration through the canopy and up to the 46 m level on the tower was completed in March, 1999.
On each level on the tower the sensors (sonic, radiation components, temperature and humidity) are interrogated by a CR23X datalogger. Calculation of mean statistics and “on-line” estimates of sensible heat flux and u* are performed by the CR23X and stored in the logger’s data buffer. These CR23X stations are periodically called by a telecommunication program from a Windows NT workstation in the tower lab building. Both 10Hz sonic data and the mean statistics are downloaded via a T1 line and written onto a magneto-optical disk (MO, 4.6 GB capacity). Ambient air is admitted to a teflon tube through an intake funnel close to the sonic anemometer array, to allow eddy correlation. It subsequently passes through a filter and is pumped through a LICOR-6262 IRGA inside the tower lab. All IRGAs are located inside the climatized lab building and are interrogated for CO2, water vapor, cell-pressure and cell-temperature by a CR23X. The lag in the IRGA data collection is accounted for by the post-processing program, using the standard method of correlation optimization, following (e.g.) Leuning and Judd (1996) . Both the raw eddy correlation data and the mean statistics are routinely stored on MO discs and transferred to Indiana University, where postprocessing and analysis occur.
UMBS-Disturbance AmeriFlux Tower (US-UMd)
elevation 239 m amsl
This tower began operation in 2007 as part of the Forest Accelerated Succession ExperimenT (FASET).
Vegetation, soils, and climate
The University of Michigan Biological Station lies on lake-border plains in the transition zone between the mixed hardwood and boreal forests. The UMBS AmeriFlux towers lie on level to gently sloping high outwash plain derived from glacial drift, with the gradually ascending slope of an interlobate moraine lying ~1 km to the south. Soils are predominantly excessively drained spodosols. Bigtooth aspen (Populus grandidentata) and trembling aspen (P. tremuloides) dominate within a 1-km radius of the eddy-covariance tower, but with significant representation by red oak (Quercus rubra), beech (Fagus grandifolia), red maple (Acer rubrum), white pine (Pinus strobus), and hemlock (Tsuga canadensis) as well. Understory is dominated by bracken fern (Pteridium aquilium) and saplings of red maple, red oak, beech, and white pine. The presettlement white pine, red pine, hemlock forest was cut around 1880, and the area disturbed repeatedly by fire until 1923.
Latitude: 45° 35′ N
Longitude: 84° 42′ W
Mean annual temperature: 6.20°C
Mean annual N mineralization: 11
Mean annual precipitation: 750 mm
Slope: 1–7 percent
Stand age: 90 years
Canopy height: 20 m
Leaf area index (LAI): 3.7
Basal area: 23.7 (m^2 ha^-1)
Max dbh: 62 cm
Mean dbh: 14 cm
Percent sand/silt/clay: 93/6/1
Texture: loamy med. sands
Classification: entic Haplorthod
Biomass distribution (kg/ha) within the 60 m AmeriFlux plot, 1997
|Tree Species||Leaves and twigs||Live branches||Dead branches||Bole||Total|
Datasets of precipitation, temperature, evaporation, and other climatological information are available from the UMBS website.