Assessment of In-situ Canopy Cover Measurement Techniques and GEDI Vertical Canopy Cover in the Indian Western Himalayan Region

Global Ecosystem Dynamics Investigation (GEDI) mission, operating from International Space Station, is a full-waveform LiDAR measuring vertical 3-dimensional structure of terrestrial ecosystems. The vertical canopy cover (CC) available from the GEDI L2B product has applications in forest ecosystem, forest health and climate change studies, and management practices. Some studies have assessed the accuracy and uncertainty of the GEDI vertical canopy cover profile product using aerial LiDAR scans and in-situ measurements. However, in-situ measurements taken using angle-of-view effectively produces canopy closure whereas GEDI measures vertical CC. Cajanus tube, regarded as ideal canopy cover measurement technique, is time consuming and impractical for larger areas. In this study, suitable in-situ canopy cover measurement methodologies were assessed alongside GEDI vertical CC. Canopy cover measurements were taken under GEDI footprints in the Indian Western Himalayan region using spherical densiometer, hemispherical photographs and digital canopy photographs with narrow angle-of-view. The plot dimensions were adjusted to accommodate horizontal geolocation uncertainty of GEDI version 2 data products. Following data collection, measurement techniques were assessed based on R-squared, RMSE and MAE.