How to get closer to actual forest stand height using GEDI? A case study in central European Scots pine stands

Global Ecosystem Dynamics Investigation (GEDI) Satellite Laser Scanning mission plays a key role in forest monitoring, conducting global measurements of forest height and structure. However, the use of various stand height metrics and definitions applied to describe forest height complicates study comparisons and the selection of most suitable GEDI metric for stand height determination. Our study was focused on finding the optimal GEDI relative height (rhG) metric to describe the height of Scots pine stands. We compared GEDI rhG parameters with several metrics commonly used as reference forest stand height (a series of Airborne Laser Scanning point cloud percentiles and relative height metrics of simulated waveforms; rhSW). Results showed that GEDI rhG metrics in the 0.95-0.99 rank range can accurately describe forest stand height (ALS reference: RMSE <= 2.79 m; %RMSE <= 12.57%; rhSW reference: RMSE <= 2.80 m; %RMSE <= 12.21%). Moreover, our analyses suggested that different rhG metrics can be used to describe forest stand height depending on its height and canopy cover to increase measurements accuracy. We recommended a set of GEDI rhG metrics for adequate height measurements of Scots pine stands that can be used by forestry practitioners.