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Effect of Forest Conversion

Effect of Tree Distance

Exchange N-Gases Summary

Long Term Continuous Measurements of NO/NO2 fluxes

Long Term Monitoring Station 'Höglwald', Bavaria, Germany

Insight measuring container
One of the three automated measuring systems
50 m tower
Tree Chambers
Tree chambers

The Höglwald is a Norway spruce-dominated forest of about 370 ha surrounded by farmland in the hilly landscape of Southern Bavaria, approx. 70 km north of the Alps and 40 km west of Munich at 11° 5' E and 48°18' N. The Höglwald site (560 m asl) is operated by IMK-IFU permanently since 1993. The site is characterized by chronically high loads of atmospheric nitrogen deposition (~30 kg N ha-1 yr-1 in wet deposition). The site is equipped with 3 fully automated, remotely controlled measuring and data acquisition systems in standard containers for continuous quantification of net exchange of trace gases (CO2, N2O, CH4, NOX) at the soil-atmosphere interface in high temporal resolution using static and dynamic chamber techniques. In addition, the site is equipped with two towers (3 m and 50 m height) for quantification of net ecosystem exchange of CO2, H2O and sensible heat. The measurements are complemented by sensors for precipitation, N-input via wet and dry deposition, soil temperature, soil moisture, stem temperature, soil heat flux, radiation as well as the vertical profiles of temperature, wind speed and wind direction.

Starting in 1993, measurements concentrated on the effect of soil liming, N-deposition, tree species, and distance from the stems of trees on the magnitude of trace gas exchange. In 1999, the focus of measurements was changed to the longterm effect of different forest management practices (clear-cutting vs. selective cutting) on trace gas exchange and the impact on the resources atmosphere and groundwater.
The Höglwald site was/is part of the EU Projects NOFRETETE and NitroEurope IP, and the Helmholtz Initiative TERENO.


Contacts: Rainer GascheRalf Kiese, Georg WillibaldHans Papen


 Instrumentation of Höglwald Site


Automated measuring systems:
  • Fully automated, remotely controlled data acquisition system
  • Gaschromatographs equipped with ECD and FID detectors for determination of surface fluxes of N2O and CH4
  • Chemoluminescence detectors combined with photolysis converter and a UV-photometer for determination of surface fluxes of NO, NO2, and O3
  • IR gas analyzers for determination of surface fluxes of CO2
  • PT-100 sensors for determination of air and soil temperature (soil vertical profile)
  • Capacitance/frequency domain technology sensors for determination of volumetric soil moisture in vertical soil profiles (20 sensors)
  • Soil heat flux (6 sensors)
  • Stem temperature (6 sensors)
  • Tunable Diode Laser Absorption Spectrometer (TGA100A, Campbell Scientific) for determination of C and O isotope ratios in soil and ecosystem CO2
Platform (50m):
  • Eddy covariance system for turbulent fluxes of CO2, H2O and sensible heat (net ecosystem exchange)
  • net radiation, global radiation, phytosynthetic active radiation, albedo
  • leaf surface temperature, air humidity, air temperature
  • wind speed, wind direction, precipitation
  • N-deposition
in 40m / 30m/ 15m / 8m and 2m height:
  • wind speed, wind direction, air humidity, air temperature


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