The sensitivity of SAR backscatter to forest windthrow gaps

Knowledge of the frequency, size and distribution of forest canopy gaps is important in understanding forest ecosystem state and dynamics. SAR data offers the potential to acquire information on canopy gaps since microwave backscatter is sensitive to vegetation structural properties. This letter examines relations between multi-waveband/polarisation backscatter and windthrow gaps in a coniferous plantation. Changes in backscatter due to the presence of windthrow gaps were evident in each waveband/polarisation configuration used, especially C-band HH. It is suggested that backscatter is sensitive not only to the presence but also the shape and geometry of the windthrow gaps, characterised in this study by gap area, perimeter and perimeter/area.