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Forest-site ecology: ecological niches of plant species

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This research focus studies how plant species respond to important growth factors in forests: light, temperature, soil moisture and nutrient availability. Another topic of this research focus is digital soil mapping (DSM) where relevant ecological soil properties are predicted for the whole forested area of Switzerland.


Our research provides new data based knowledge for the scientific community, for the forest management and for educational purposes.
We research and document…
… the ecology of forest plants in relation to environmental factors – light, temperature, water and nutrients,
… ecological indicator values for forest plant species,
… the competitive ability and the water use strategies of tree species across their distribution ranges,
… the potentials and risks of Swiss forest soils using digital soil mapping (DSM).

An archive for soil samples and soil data base

Data are stored in an Oracle database containing both vegetation records and soil profile data from currently 1200 forest plots all over Switzerland (see map). The corresponding soil samples are archived in the “Pedothek” at WSL (see photo), a huge archive for soil samples.

A large parameter set of morphological, chemical and physical soil data has been obtained from the soil profile analyses. Vegetation records are available separately for the herb, shrub and tree layer. Additional site data such as climate and geology complete the data set at each plot.

For a subset of the plots, long-term data series are available of various environmental factors (e.g. temperature and soil water potential) as well as data related to stem radius increment for beech, oak, spruce and Scots pine.

Data are made available to interested researchers and forestry practitioners on request.


Vegetation, soil, soil water potential and stem radius data are assessed with the following methods:

  • Forest vegetation is recorded according to Braun-Blanquet (1964) as well as Mueller Dombois and Ellenberg (1974).
  • The methods used for the analysis and interpretation of soil data are published in “Waldböden der Schweiz” (Volume 1). Soil morphology is recorded according to WSL standard field methods. Chemical and physical soil parameters are analyzed in the laboratories at WSL.
  • Soil water potentials are recorded using Decagon MPS-2 sensors and tree radius variations using point dendrometers of the company Natkon.
  • The water cycle and drought is simulated for past and future climate in all 1200 forest stands using models (Coupmodel).
  • A wide range of statistical methods is applied to analyze tree-growth as a function of environmental factors.
  • For digital soil mapping we use (geo)statistical methods and state-of-the-art GIS-technology.


Our partners for investigating growth and water use strategies of tree species is TreeNet, and the geostatistic group of ETH-Z for digital soil mapping.

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Soil and vegetation data originate from about 1200 forest stands across Switzerland.
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Archive of soil samples at WSL (Pedothek) and scheme of the WSL soil database. (Photo: Marco Walser)
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CoupModel: a coupled heat and mass transfer model for soil-plant-atmosphere systems.
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Point dendrometer for the detection of stem radius variations (below) and sensors for air temperature and air humidity (above). (Photo: Lorenz Walthert)
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Sensors for recording soil water potential. (Photo: Lorenz Walthert)
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Stocks of organic carbon in 0-10 cm soil depth across the forest area of Switzerland as predicted by digital soil mapping.