Too many monocultures, compacted soils and challenging environmental conditions: our trees are increasingly suffering. Studies show that factors such as biodiversity loss mean that forests no longer serve as CO2 sinks, but instead emit carbon dioxide. It is therefore becoming increasingly important to be able to respond to the needs of plants as early as possible. Modern monitoring tools can help here.
However, measurement technology is usually expensive and often has to be attached invasively to or on plants. In the case of trees, this means that we have to break open the protective bark to obtain information from inside. At the same time, there are too many different sensors whose data cannot be easily combined with each other.
The TreeMon project takes a different approach, which works superficially and, in the best case scenario, also comprehensively.
Trees “talk” about their problems
Even if we can’t always perceive it with our senses, plants are constantly communicating their current health and growth requirements. The startup Hortyia, for instance, is attempting to decode this “plant language” using its own proprietary language model. Historically, we’ve reported on numerous projects that utilise sensors embedded directly into leaves or bark.
According to Mario Hopfner from the German Private Institute for Environmental Analysis (IfU) in Chemnitz, this is precisely where TreeMon differs from other approaches: “Sound allows us to look inside objects non-destructively.” His team investigated various attachment methods, testing the sensors on the outer bark as well as the inner bast or cambium layers. Although the recording quality improved the deeper they reached into the tree, they found that even recordings with higher background noise provided sufficient data for meaningful analysis.
Consequently, Hopfner explains that his team limited their measurements to “merely smoothing the bark slightly to create a suitable contact surface.” The researchers attached five different “TreeMon sensor” prototypes to various trees to gather a wide range of data. These “acoustic emission sensor nodes” also record additional environmental factors such as temperature and humidity.
To date, the TreeMon team has tested five sensors on different trees. Here is the translation and improvement for the second passage:
British English Translation
“By attaching sensors directly to the tree, we can record sounds that are usually imperceptible to the human ear—such as the snapping of individual wood fibres or the feeding noises of pests,” explains Mario Hopfner.
Although the sensors, developed by the research team in collaboration with Teletronic Rossendorf GmbH, can be fitted universally to various tree species, the initial test recordings revealed distinct differences in the data collected.
Similar principle, different scenario
The increasing drought is also raising the risk of forest fires. The Brandenburg-based start-up Dryad is developing sensors designed to provide early warning of forest fires.
“Overall, trees are incredibly diverse. I wasn’t fully aware of the extent of this before the project began. There are numerous factors to consider: age, size, girth, species, location, and many other characteristics have a fundamental impact on the measurement data and its subsequent analysis,” says Hopfner. For this reason, the TreeMon team is also collaborating with OGF GmbH and the fruit processing firm Sora GmbH. These botanical experts provide insight into plant health and physiological behaviour.
Research data to be made open-access
Another strength of the project is that the recorded audio tracks are not restricted to proprietary systems. If a similar project were to develop different microphones that record the same frequencies, the data could be analysed together. TreeMon also plans to make its data publicly accessible in the future, enabling further development by other research teams.
The data from the sensors is to be collected on a dashboard. This allows users to view the information directly and compare it. Although the data is currently only accessible within the project, the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) plans to make the measurement data publicly available in the future. This will be done via the project website or via cloud storage.
In 2026, the TreeMon project will have already entered its final six months of implementation. So if you see trees with microphones in the future, they won’t be recording a new podcast – they may be equipped with TreeMon sensors.
