Digitized Downed/Standing Trees in the Mission River Floodplain

Downed trees (N=9505) were digitized by members of the FLUD Research group (faculty and student researchers). Student researchers consist of graduate and undergraduate students. Undergraduate student researchers worked at the supervision and expertise of faulty and graduate students. Interpretation of whether a given location consisted of a downed tree was based on all points in a LiDAR point cloud that are lower in elevation or intercepted at a fixed elevation (1.0 m) above the ground. These identified LiDAR points were then transformed into raster maps that allowed the personnel to use geometry and expert knowledge to identify the downed trees. For the environmental analyses, only downed trees were discernible structure are used (N=4571 total; N=4283 within model evaluation domain). This was objectively conducted with a metric that evaluates the area of both ends of the downed tree. Those with a normalized difference between the two halves of the downed tree above a threshold (0.15) are considered as having a tree crown, root wad, and direction that the tree fell. Standing trees are derived from first-return LiDAR point-cloud data using the L3Harris GeospatialTM ENVI® LiDAR extension.