New Zealand Journal of Ecology (2005) 29(1): 95- 103

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

Research Article
Harley D. Betts 1,*
Len J. Brown 1,2
Glenn H. Stewart 3
  1. Landcare Research (New Zealand) Ltd, Private Bag 11052, Palmerston North, New Zealand
  2. Current address: New Zealand Climate Change Office, PO Box 10362, Wellington, New Zealand
  3. Soil, Plant and Ecological Sciences Division, Lincoln University, PO Box 84, Lincoln, New Zealand
*  Corresponding author

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.