Application example: Development of a DendroModule

as part of the MW3 joint project of the Forest Climate Fund

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ecoTech is a partner in the MW3 project entitled ‘Standardised monitoring of growth responses of important forest tree species to extreme climatic events’. (https://mw3-project.com/).

The redevelopment  of the Dendro module was largely initiated by our project partner, Dr Burkhard Neuwirth of DeLaWi Jahrringanalytik. Dr Neuwirth has been a recognised expert in dendroecology for decades. Among other things, he has been working intensively for over 15 years on suitable high-resolution, automated technical measurement systems and recognises that most of the systems used have various deficits. These disadvantages were to be overcome with the new development of a dendro module and the associated improved sensor technology.


Our new DendroModul therefore has functional advantages over previous technical solutions:

  1. Based on the Granier principle, the sensor measures both upward and downward sap flow in the xylem using three vertically aligned needles.
  2. Two additional, horizontally offset needles record stem temperature, enabling more accurate determination of flow velocities that are sensitive to temperature variations.
  3. Furthermore, the needles can be inserted into the xylem at distances of at least 5 cm from one another (the standard spacing in the MW3 project is approx. 10 cm). This spacing can be of significant importance, since the tree responds to needle insertion by forming wound tissue, which inevitably alters the measurement signal in the immediate vicinity of the needles. The wound response can penetrate up to several centimetres into the tissue and distinctly affects sap flow in that area. The closer the needle spacing, the greater the proportion of callus tissue between the needles, and the more the measurement signal deviates from natural conditions. According to Dr. Neuwirth, a spacing of only a few millimetres allows for meaningful use of the measurement data only over a very short period.
  4. Another key feature is that the needles can be individually exchanged and replaced.

The DendroModule can be used at existing dendrometry stations or as part of DHC stations, which link dendrometric measurements with soil moisture and climatic data (Dendrophysiological, soil-Hydrological and Climatological). A total of 72 DendroModules were installed at DHC stations of the MW3 project in autumn 2024.

 

As part of the MW3 project, a new type of modular measuring system is being developed using the so-called DHC station for standardised real-time monitoring of tree growth, soil conditions and climatic conditions. The system is based on the established SoilNet sensor network for recording soil hydrological variables (HydroModule) and is supplemented by a ClimateModule (air temperature, air humidity, precipitation), a DendroModule (sap flow, radial stem growth) and a mobile RadiationModule (PAR, R/FR). These modules have been optimised in terms of energy and cost, and offer a flexible combination option (source: mw3-project.com/waldmonitoring/).

As part of the MW3 project, ecoTech was commissioned to develop a new module (DendroModule) for improved automated and high-resolution measurement of sap flow and thickness growth on trees.

The following partners are involved in the MW3 project:

  • RWTH Aachen University, Department of Geography, Physical Geography and Climatology (project coordination)
  • Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences Agrosphere IBG-3
  • Philipps University of Marburg, Laboratory for Climatology and Remote Sensing
  • Helmholtz Centre Potsdam – German Research Centre for Geosciences GFZ, Division of Hydrology & Climate Dynamics and Landscape Evolution
  • Helmholtz Centre for Environmental Research GmbH – UFZ, Department of Ecological System Analysis & Hydrosystem Modelling
  • ecoTech Umwelt-Messsysteme GmbH
  • DeLaWi Jahrringanalytik
  • Landesbetrieb Wald und Holz NRW