Forest canopy gap detection and characterisation by the use of highresolution Digital Elevation Models

The remote identification of forest canopy gaps from Digital Elevation Models (DEMs) built from aerial photographs is potentially a viable alternative to ground-based field surveys. In this study a DEM-based gap-finding algorithm, given suitable experimentally determined input parameters, yielded canopy gap statistics for a study area that were consistent with ground-based survey data from the same area. The method could thus be ‘trained’ to replicate ground-based results for a small test area of beech (Nothofagus) forest, with the potential for it to be applied to larger areas of forest of a similar type to gather canopy gap data with relatively little additional field work. The use of a DEM-based method also has the advantage that the results are easily analysed and mapped using commonly available GIS and cartographic software.