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Cold Season NO Fluxes

Decadal variability of trace gas fluxes

Effect of Forest Management

Effect of Tree Distance

Exchange N-Gases Summary

Long Term Continuous Measurements of NO/NO2 fluxes

Long Term Monitoring Station 'Höglwald', Bavaria, Germany

Hoeglwald Banner
Insight measuring container
One of the three automated measuring systems
Hoeglwald Control Site
Höglwald control site

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 towers for quantification of net ecosystem exchange of CO2, H2O and sensible heat. The measurements are complemented by sensors for precipitation, soil temperature, soil moisture, stem temperature, soil heat flux, radiation as well as the vertical profiles of temperature, wind speed and wind direction.

During the past 3 decades, scientific activity at the Höglwald forest site focused on different drivers affecting forest ecosystem functions e.g. acidic rain, tree species composition and forest management practices. Overall, the C and N trace gas exchange dataset of the Höglwald is worldwide the most comprehensive, complete and long-lasting dataset on trace gas exchange and environmental controls of a forest ecosystem.

Contacts: Rainer GascheRalf Kiese, Klaus Butterbach-Bahl


 Instrumentation of Höglwald Site


Automated measuring systems:
Tree Chambers
Tree chambers
Installation of Soil Gas Sampling System
Installation of Soil Gas Sampling System
  • 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
  • Soil Gas Sampling System along 3 soil vertical profiles in 3 depths each for determination of soil concentrations of trace gases (e.g. N2O, CH4, CO2, NO)


 Instrumentation of Höglwald Site


50 m tower

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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