Ants in Labyrinths: Lessons for Critical Landscapes
Percolation theory provides a starting point for models for the movement of organisms in fragmented landscapes. We simulated six general rules for movement on three general landscape patterns with different degrees of habitat fragmentation. Fragmentation pattern affects migration success. Organisms moving within habitat patches are restricted by fragmentation, but the response is less abrupt as one moves from random to hierarchical to fractal landscapes, respectively. Success for organisms moving along edges is more strongly differentiated by landscape pattern. Success and speed are usually directly related, but indirect relations may indicate rare but efficient pathways or cul-de-sacs. We propose that general rules can be applied to the identification of landscapes near critical levels of fragmentation that will respond sensitively to increases in fragmentation or efforts at restoration.