View of a small weather station that is powered by a small solar panel. In the background about 20 high Douglas fir, which belong to the experiment.

Kaltenborn (Germany)

BIOTREE- Biodiversity research on native tree species in different planted combinations - location in the middle of Germany.
Kaltenborn near Bad Salzungen is one of the three sites of the BIOTREE research project

Description & History

The area covers an area of 20 hectares, which used to be a military training area and is now divided into 16 sub-areas that have been reforested - "the research forest of tomorrow".

The areas were reforested with native tree species, but in different mixtures with changing numbers of species. There are areas with only one species, so-called pure stand, but also areas with 2, 3, 4, up to 8 species. In these areas, each tree species is planted in groups of 8 x 8 meters.

In addition, part of the area is used for an experiment where all tree species are planted mixed, so that all have different neighbors and competition among them can be explored.

Dominant species might suppress some or all of the other tree species in the different mixes.

Tree growth and wood increment are measured regularly, but parameters such as nutrient leaching and groundwater recharge rates are also recorded.

Tree species: Picea abies (spruce), Pseudotsuga menziesii (Douglas fir), Quercus petraea (sessile oak), Fagus sylvatica (beech) and as secondary tree species Abies alba (silver fir), Fraxinus excelsior (common ash), Acer pseudoplatanus (sycamore maple) and Sorbus aucuparia (rowan). When the plants were planted in winter 2003/2004, they were 3-4 years old and 20-60 cm high.

The project is financed by DEGES and the Max-Planck-Institute for Biogeochemistry - the responsibility of the project lies with Prof. M Scherer-Lorenzen, University of Freiburg.

The meteorological station was set up in November 2003 by our department (Field Experiments and Instrumentations Group).


Reforestation area

Subplots with different tree species diversity
Latitude: 50.77
Longitude: 10.22
Elevation: 328 m a.s.l.    


  • 2003 until today
  • Competition experiment
  • Tree growth
  • Timber growth
  • Meteorology


  • BIOTREE TreeDivNet


  • University of Freiburg - Prof. Dr. Michael Scherer-Lorenzen

Variables & Instruments


  • Wind speed - cup anemometer A100R, Thies
  • Air temperature and humidity - temperature/humidity sensor KPC1_5-ME, Mela
  • Precipitation - heated tipping bucket precipitation gauge, Thies
  • Solar radiation - pyranometer CM3, Kipp & Zonen

Soil conditions

  • Soil temperature - Soil temperature sensor PT100, do-it-yourself
  • Soil moisture at 5 depths - soil moisture sensor ML-2x, Delta-T

Data acquisition

  • Meteorological data - Data logger CR10X, Campbell Scientific
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