LiDAR (Light Detection and Ranging) is currently being used to extract the biophysical characteristics of forests. LiDAR can provide extensive information about tree canopies; pulses reflected back to the sensor can represent understory vegetation as well as partial tree canopies below the dominant trees. Canopy structure can yield valuable clues regarding the biodiversity, and processes affecting the ecology of forest stands. In addition structural information can provide insight into other processes such as fire behaviour and the distribution of fuels. The objective of this paper is to provide an algorithm to identify and delineate partial tree crowns underneath dominant canopies. The study area is located in the Greater Victoria Water District, west of Victoria, British Columbia, Canada. Nine plots were chosen to represent the study area. A complete census was conducted in the summer of 2005 to provide information about height of living crown (HLC), tree height, diameter at breast height (DBH), and tree dominance (based on the criteria: suppressed, intermediate, co-dominant and dominant). Using an algorithm previously developed by the Hyperspectral and LiDAR Research Group (Department of Geography, University of Victoria), treetops and canopies of the dominant trees must first be identified and delineated. Then, using the HLC as a threshold for identifying canopy height, it is possible to remove the LiDAR points representing the dominant tree crowns from the dataset. With this newly developed algorithm, it is possible to identify and delineate understory tree canopies.
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