A reference value for the interior-to-edge ratio of isolated habitats

Isolated habitats, the consequence of the fragmentation process, are the ob ject of external disturbance. This divides the patch area into two zones: i nterior and edge. The interior-to-edge ratio quantifies the potential distu rbance impact. A method is presented to calculate a reference value for the interior-to-edge ratio, based upon the minimum edge for a given interior. The method is based on pixel geometry features and mathematical morphology. A corrected interior-to-edge ratio is defined using the reference value. T he method is illustrated for woodlot fragments in the Belgian Kempen region .