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winter, with the dead leaves having a noticeable ‘orange/brown’ colour and there is
no photosynthetic vegetation present in the canopy. By contrast, in summer, bracken
has very high productivity and a closed canopy. Using the ratio between these two
states allows bracken to be identified with relative ease. The timing of the ‘leaf-on’
and ‘leaf-off’ imagery however needs to be considered in the biogeographical
context. In Wales a ‘leaf-off’ image before March contains too much shadow from
Fig. 5 Regional scale mapped output for an area of Norfolk
K. Medcalf et al.
winter, with the dead leaves having a noticeable ‘orange/brown’ colour and there is
no photosynthetic vegetation present in the canopy. By contrast, in summer, bracken
has very high productivity and a closed canopy. Using the ratio between these two
states allows bracken to be identified with relative ease. The timing of the ‘leaf-on’
and ‘leaf-off’ imagery however needs to be considered in the biogeographical
context. In Wales a ‘leaf-off’ image before March contains too much shadow from
Fig. 5 Regional scale mapped output for an area of Norfolk
K. Medcalf et al.