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Using ultrasonic sensors to ‘hear’ plants grow

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Automated weather stations measure wind, temperature, snow depth and other data. But these IMIS weather stations, operated by cantonal authorities, can do much more. Since the 1990s, their ultrasonic sensors have also been recording how plants within a 75 cm radius have been growing. With this unique dataset, collected from around 130 stations, researchers of SLF, WSL and the University of Neuchâtel have been able to reconstruct how vegetation has developed over the course of the last 20 years, and how alpine plants will react to climate change in the future.

The first results show that the duration of snow cover at the stations analyzed has reduced markedly in recent decades – due primarily to earlier snow melt in the spring. The plants reacted to these changing environmental conditions accordingly: the start of their growth period showed a strong correlation with the date when the snow began to melt, regardless of the station’s elevation. In other words, the sooner the area became snow-free, the sooner the plants woke from their hibernation. Plants developed more slowly, though, in years when the snow melted early than in years with a late snow-melt. The air temperature turned out to be responsible for this effect; it wasn’t high enough earlier in the year to provide the plants with sufficient warmth for their growth. (Christine Huovinen, Diagonal 2/16)