The more advanced and tailored the technology, the earlier infested trees can be identified and removed. Langning Huo’s award-winning research, which aims to combine drones with small, lightweight spectral cameras, could become a business concept with the potential to save millions of cubic metres of forest every year – in Sweden alone.
The battle between spruce bark beetles and spruce trees is a matter of life and death. Academia, forest owners and the authorities are working closely together to find sustainable solutions going forward. It’s true that the spruce bark beetle is a native species that does its bit for forest biodiversity. However, it thrives in hot, dry weather, which means that climate change is making the problem increasingly acute.
The hot, dry summer of 2018 showed that things can get really bad, with record-breaking infestations being witnessed. Because while a warmer climate is bad for spruce trees, the opposite is true for spruce bark beetles, which are the insects that do most damage in Swedish spruce forests. Healthy, strong spruces are able to kill off the pest. But spruces that are stressed by heat and drought easily fall prey to the spruce bark beetle, which lays its eggs in tunnels in the bark. From there, the larvae then eat their way out, damaging or killing the trees.
“It’s important to get infested trees out of the forest as quickly as possible,” says Langning Huo.
She received the SLU Umeå and Sparbanksstiftelsen Norrland’s 2024 innovation prize for her research, with the justification that “The winning idea has succeeded in seeing things that nobody has seen before. The jury considers this to be a simple, yet scalable solution with considerable potential to solve an important problem for the forest industry.”
Using satellites, remote sensing of both forests and fields, for example, has been performed for a number of years. Drones have also started to be used in recent years, and with technological developments moving towards smaller and simultaneously increasingly advanced devices, new levels of precision are now becoming possible.
And while traditional remote sensing cameras and sensors do not measure the wavelengths at which the initial physiochemical changes are visible, Langning Huo’s own research has identified a green band at 530 nanometres on the electromagnetic spectrum, which captures exactly the information being sought.
“Our trials show that we are finding 80% of early infestations, compared to 28% previously.”
The camera that Langning wants to develop only needs to be sensitive to the wavelength bands indicating the really early signs of spruce bark beetle infestation. Even at this early stage, there are changes in the light reflections from the trees’ needles.
“A small drone system like this, fitted with a camera, would be much cheaper than the current systems, which cost around SEK 2 million each. A small, specialised drone camera, when mass-produced, would cost an estimated SEK 100,000.”
When mounted on a drone, the camera is capable of analysing individual trees in detail. And in addition to providing information about early spruce bark beetle infestations, it can provide data for a tree stress index that Langning Huo has developed. Data from drone-mounted cameras and data from satellite images could also complement and validate each other.
The problem of pests destroying standing forest is in no way specific to our latitudes. Similar technological solutions are needed around the world. This is the case in China, for example, where Langning Huo completed her PhD at Beijing Forestry University.
“After a year as a PhD student, however, I returned to Sweden and SLU in Umeå, and I’ve now been here for five years. I like the way Swedish researchers collaborate and communicate, as well as the excellent cooperation between academia and industry aimed at developing methods that can be applied.”
Inspired by this, Langning Huo, with the aid of SLU Holding, has conducted an initial market analysis of her innovative ideas. And now, in 2025, she is thinking in earnest about the way forward.
“I would like the results of my research to be put to practical use, although some further research is still necessary before this can be commercialised. And I’m not sure yet if I want to offer consultancy services or focus on the development of small, customised cameras. In that case, it will be important to find long-term, sustainable solutions that match the lightning-fast pace of technological developments. This is a very hot topic!”
https://www.sciencedirect.com/science/article/pii/S0924271624002946
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