In January 1998, between 40-100 mm freezing rain accumulated on trees in Eastern Canada causing significant damage to the forests. Damage in the mostly deciduous forests of the Gatineau Park, Quebec was studied using airborne colour infrared (CIR) photography, hemispherical photography and standard field methodologies. Effective leaf area index (LAI_e) and canopy cover were measured using hemispherical photography acquired by a circular fish-eye lens and airborne image-based methods that incorporate spectral components of the imagery. The multispectral airborne data were acquired with a Vinten 70 mm camera and Kodak 2443 CIR film in mid-August 1998. Hemispherical photography proved to be a feasible method to derive LAI_e and canopy cover for the test plots, although the method slightly under-estimates LAI. Spectral measures extracted from the scanned aerial photography were highly correlated with the hemispherical photography measures but were weaker with the field parameters. These low-cost image acquisition and analysis techniques will be used in spatial monitoring of the response of the forest to this rare event.
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