Ecosystem structure (DP3.30015.001)

Forests store and sequester a considerable proportion of the terrestrial global carbon budget. Forest canopy metrics are directly measurable with LiDAR sensors because laser pulses will be reflected from the uppermost canopy layers and remaining energy will penetrate to, and reflect from, under-story and the ground surface. The near simultaneous direct measurement of ground and canopy elevation allows the canopy height to be estimated through differencing. The CHM is generated by creating a continuous surface of canopy height estimates across the entire spatial domain of the LiDAR survey. The CHM is derived directly from the LiDAR point cloud. The LiDAR point cloud is produced from LiDAR return signals from both surface features and the true-ground as LiDAR pulses will be reflected from the uppermost layers of the canopy, as well as the underlying ground surface. To produce the CHM, the point cloud is separated into classes representing the ground and vegetation returns. The ground classified points allow calculation of a height normalized point cloud to provide a relative estimate of vegetation elevation. A surface is then generated using the height normalized vegetation points to produce the CHM. Any canopy heights less than 2m are set to zero. Latency: AOP data will be available 60 days after the final collection day at a site.