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Site Info (CH-DAV)

 

Site Description

The Seehornwald Davos research site is located at 46°48’55.2” N, 9°51’21.5” E (Google Maps) at 1639 m a.s.l. in the middle range of the subalpine belt in the eastern part of the Swiss Alps.

The coniferous forest is dominated by Norway spruce (Picea abies (L.) Karst.) with a mean canopy height of 9.9 m in the eddy covariance footprint area (tallest trees reach 41 m), and a leaf area index of about 4 m2 m-2. The average tree age in the eddy covariance footprint is approx. 60 years, with some specimens reaching over 350 years. The understorey vegetation is rather patchy, covering roughly 30% of the forest floor, and is mainly composed of dwarf shrubs, primarily Vaccinium myrtillus and Vaccinium gaulterioides as well as mosses.

The research site offers a unique combination of ongoing long-term measurements of regional climate, CO2 and microclimate profiles through the forest, tree physiological records such as sap flow and continuous stem radius changes, turbulent fluxes by eddy covariance, continuous atmospheric NOx, SO2 and O3 concentrations, and multiple properties of the vegetation (e.g. crown transparency, litterfall, rain deposition) and soil structure. Check the history of the Seehornwald Davos research site to get more information about the equipment installed.

The long continuous track record of measurements makes this research site a predestined location for investigations about (missing) links between climate change and tree physiological adaptations and to a hot spot for addressing questions about the ecosystem carbon balance in relation to soil related components and tree physiological processes under changing environmental conditions.

Current land use includes little thinning activities. In 2006, an area of 25 x 70 m (1750 m2) within the NE-part of the footprint of the EC site was harvested at the end of October.

 

Location

  • Altitude: 1639 m a.s.l.
  • Altitudinal zone: subalpine
  • Country: Switzerland (Canton Graubünden)
  • Coordinates: 46°48’55.2″N / 9°51’21.5″E (46.815333, 9.855972) (Google Maps)
  • FLUXNET identifier: CH-Dav

 

Vegetation

Where available, numbers are given separately for ICOS sparse measurement plots (SP plots) and ICOS continuous plots (CP plots).

There are differences between these two types of plots, which originatee from the fact that the CP plots, which have been operated for more than 25 years (starting before ICOS), have never been thinned, while the surrounding forest is continuously harvested, thus management keeps the stand smaller and also younger.

The SP plots are located within the eddy covariance footprint area.

  • Vegetation: coniferous forest
  • Land cover (IGBP classification): Evergreen Needleleaf Forests (ENF)
  • Main tree species: Picea abies (L.) Karst
  • Mean tree age Picea abies:
    • SP plots: 60 yrs (some specimens reaching 350 yrs)
    • CP plots: 106 yrs
  • Mean tree height:
    • SP plots: 9.9 m (max. 41 m)
    • CP plots: 18.3 m
  • Top-height diameter (quadratic average diameter of the 100 thickest trees per ha): 47.0 cm
  • Woodland association after EK72: 58: Larici-Piceetum
  • Leaf area index (LAI): 4 m2 m-2
  • Average number of stems per hectar:
    • SP plots: 1061
    • CP plots: 995
  • Average stem diameter at breast height:
    • SP plots: 12.5 cm
    • CP plots: 22 cm
  • Average basal area of stems per hectar:
    • SP plots: 40.6 m2
    • CP plots: 54.7 m2
  • Average radial stem growth per year:
    • CP plots: 1.2 mm yr-1, 23 µm d-1
    • On average, the trees grow 220 hours yr-1, mainly at night with the highest growth at 5:00 in the morning.
  • Long-term Forest Ecosystem Research (LWF):
    • LWF Date of installation: 15 Jun 2006
    • LWF Number of trees BHD >= 12 cm (2006): 498
    • LWF Size of the plot: 0.6 ha

 

Management

  • Management system: high forest
  • Silvicultural system: group selection
  • Current land use includes little thinning activities.

 

Climate

Air Temperature

  • Mean annual air temperature: 4.32°C (1997-2022)
  • 5 warmest years: 2022 (5.6°C), 2018 (5.3°C), 2020 (5.2°C), 2015 (5.1°C), 2011 (5.1°C)
  • 5 coolest years*: 2010 (2.9°C), 2005 (3.2°C), 2004 (3.7°C), 1999 (3.7°C), 2013 (3.7°C)
  • Lowest number of half-hours < 0°C: 2014 (4256), 2011 (4272), 2015 (4490), 2022 (4543), 2020 (4548)
  • Highest number of half-hours > 20°C: 2003 (689), 2015 (619), 2022 (565), 2017 (516), 2006 (501)
  • Highest number of half-hours > 25°C: 2019 (98), 2015 (56), 2013 (55), 2012 (33), 2022 (29)
  • Highest measured air temperature: 28.7°C (26 Jun 2019, half-hourly average between 14:00 and 14:30)
  • Lowest measured air temperature: -25.0°C (4 Feb 2012, half-hourly average between 8:30 and 9:00)

 

Precipitation

  • Mean annual precipitation: 876 mm (1997-2022)

 

Nearby meteo stations

 

Projects

A list of past and ongoing projects can be found here: Past and ongoing projects at Davos Station

 

Tower sharing

The tower is owned by the Federal Office for the Environment (FOEN).

The following institutions share the facilities at CH-DAV:

  • Swiss Federal Laboratories for Materials Science and Technology (empa)
  • Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)
  • Institute for Snow and Avalanche Research (SLF)
  • Swiss Federal Institute of Technology Zurich (ETHZ)

The following research / environmental  observation networks are currently active at CH-DAV:

National :

  • National Air Pollution Monitoring Network (NABEL)
  • ICOS Switzerland (ICOS-CH)
  • TreeNet: The biological drought and growth indicator network
  • Long-term Forest Ecosystem Research (LWF)
  • Swiss FluxNet

International:

  • Ecosystem Research (ExpeER)
  • Long Term Ecological Research (LTER)
  • ICP Forests: the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests
  • PrometheusWiki – A Wiki for PROtocols, METHods, Explanations and Updated Standards in Ecological and Environmental Plant Physiology (Link to stem radius changes)

Characteristics of the tower:

  • 35 m scaffolding with pre-defined booms (5)
  • Climate-controlled hut next to the tower

Additional instruments:

  • Possible, but needs to be in agreement with all partners (see above).

Internet connection:

  • ADSL line, provider Swisscom, stable connection
  • connection shared between Swiss Federal Laboratories for Materials Science and Technology (empa), Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and Swiss Federal Institute of Technology (ETH Zürich)
  • download rate: 4 Mbit
  • upload rate: 1 Mbit

 

Power availability 

  • Source: grid power
  • currently 60 A line, can be extended to 125 A
  • 25 mm diameter cable

 

Video

25 years of CO2 flux measurements in Davos (2022)

More videos can be found on Videos (CH-DAV).

 

Webcam

 

More Info

 

Last Updated on 4 Sep 2023 02:01