The canopies of complex ecosystems such as tropical rainforests are difficult to assess with conventional ground-based methods. Today, drone-based imaging offers new possibilities to study and better understand key canopy processes such as tree transpiration (water use). In this study, which was led by Dr. Alexander Röll and Dirk Hölscher (University of Göttingen), we used a multi-copter drone equipped with a high resolution camera to process 3D point clouds of a tropical rainforest canopy in Indonesia. For selected sample trees, we then used the 3D point clouds to calculate crown dimensions and to assess the shape, leaf density and exposure of each crown, which in our case was used for explaining differences in tree transpiration (as observed from sap flux measurements in the tree trunks). Our study demonstrates that 3D point cloud analysis is a very promising tool for better understanding ecological processes in tree-dominated ecosystems such as forests or agroforestry systems, allowing for research that would be extremely challenging or impossible using conventional ground-based methods.
Reference: Röll A, Kang T, Hahn P, Ahongshangbam J, Ellsäßer F, Hendrayanto, Sharma P, Wintz T, Hölscher D, 2023. Complex canopy structures control tree transpiration - A study based on 3D modelling in a tropical rainforest. Hydrological Processes 37, article e15045. doi: https://doi.org/10.1002/hyp.15045
