On the ''bicycle'' into the trees

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In Dutch forests, research is being done into the possible damage that the drought and bright sunshine have caused to trees. Employees of the Stichting Verbetering Houtopstand from Wageningen climb in Douglas firs to check the trees, using a single-trunk ladder and a tree trike, rings with which one can climb into a tree along a trunk.

Human-made No record of this work says a model made it. What this means.