The interior-to-edge breakpoint distance as a guideline for nature conservation policy

A method is proposed to quantify disturbance impact on isolated habitats. F or every landscape patch, the breakpoint distance, defined as the penetrati on distance for which equality of interior and edge habitat is observed, ca n be calculated. Disturbance with equal impact at all patch sides is assume d. Effects of patch compactness, size, convolution, and perforation are dis cussed. The potential use of the measure for nature reserve design is discu ssed. The breakpoint distance follows the reserve design guidelines for ind ividual patches, based on island biogeography and is consistent with the fo rm and function principle. A large breakpoint distance is preferred for nat ural habitats. Small size, small compactness, intense convolution, and the occurrence of many gaps depress the breakpoint distance.