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The biological drought and growth indicator network

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TreeNet - biological drought and growth indicators from trees

TreeNet is an international monitoring and research network in which automated tree stem radius fluctuations measured with point dendrometers are analyzed in terms of forest ecosystem responses to climate change. A continuous stream of microclimate and tree physiology data provides real-time information on tree water relations and tree growth. 

Imbalances in tree water relations - quantified as tree water deficits - are interpreted as biological drought indicator for entire forest ecosystems.

Current stem growth rates are related to the ones of past years and interpreted as indicator for forest growth. Combinations of indicators are used as early predictors for the expected annual carbon sink of forest ecosystems.

TreeNet produces the basic data needed to extrapolate research results from the eddy flux supersites Seehornwald Davos (LWF/ETHZ/SwissFluxNet) and Lägeren (LWF/ETHZ/SwissFluxNet) for entire landscapes. We closely collaborate with the Long-term Forest Ecosystem Research Programme (LWF/WSL), the ETHZ and the Institute for Applied Plant Biology (IAP).

For further information about data, results, methods and products of TreeNet visit

TreeNet offers scientific and public informations on:

Water relations of forest ecosystems:

  • Realtime tree water deficits.
  • Daily biological indicator for drought stress of forest ecosystems.
  • Daily estimation of missing rain to cover the current water deficit.

Carbon balance of forest ecosystems:

  • Realtime stem growth rates of trees.
  • Indicator for phenological growth phases.
  • Biological indicator for the net ecosystem productivity (NEP) of different forest types.

Project partners

  • Federal Office for the environment /Bundesamt für Umwelt BAFU
  • Long-term Forest Ecosystem Research Programme LWF of Swiss Federal Research Institute WSL
  • Swiss Federal Institute of Technology Zurich ETHZ
  • Institute for Applied Plant Biology IAP
  • DecentLab - Decentralized monitoring solutions
  • - Home of the point dendrometers

Swiss TreeNet sites

TreeNet super sites:

TreeNet dendrometer sites:

WSL Contact

Roman Zweifel

Matthias Häni

Related projects

ICOS: Matthias Häni, Roman Zweifel und Koni Steffen (WSL)

PhD-project Elena Perez Ojeda ETHZ/WSL: Forest_CH (ETHZ/WSL)

Long-term Forest Ecosystem Research Programme LWF (WSL)

Tree response to climate change (WSL)

Seehornwald Davos research site (WSL)


  • Zweifel R., Eugster W., Braun S., Dobbertin M., Schaub M., Etzold S., Buchmann N.  (2011). TreeNet - Bäume als biologische Indikatoren für Trockenheit und Kohlenstoff-Aufnahme von Waldökosystemen. Poster, Forschungsmarkt Davos, 20 March 2011 (PDF 176 KB).
  • Etzold, S. (2010). The carbon dioxide budget and respiration components of two contrasting forest ecosystems in the Swiss Alps. Dissertation. ETH Zurich. Diss No 19061. 176 p. (link to pdf coming soon).
  • Zweifel R., Eugster W., Etzold S., Dobbertin M., Buchmann N. and Häsler R. 2010. Link between continuous stem radius changes and net ecosystem productivity of a subalpine Norway spruce forest in the Swiss Alps. New Phytologist, 187: 819-830. (PDF 510KB).
  • Zweifel R., Steppe K. and Sterck FJ. 2007. Stomatal regulation by microclimate and tree water relations: interpreting ecophysiological field data with a hydraulic plant model. Journal of Experimental Botany, 58, 2113-2131. (PDF 1437KB).
Keywords TreeNet, carbon balance, Kyoto protocol, tree water relations, drought stress, climate change