The history of networks

The concept of core areas surrounded by a potentially hostile matrix of different habitats originated with the theory of island biogeography, first suggested by MacArthur and Wilson in 1967. This theory suggested that the number of species on an island was affected by both the size of the island and its distance from continents and other islands. Distant islands were colonised more slowly by new species as plants and animals had further to travel.

This theory can be applied to actual physical islands, surrounded by a potentially hostile sea. But it can also be applied to islands of habitat within a sea of unsuitable habitat. And it's this idea which has been developed into the networks concept - if islands (or core areas) of habitat can be linked together in some way, then species can migrate between those islands more rapidly.

Recently that opportunity to migrate has become more important as we accept that many species will need to shift northwards in response to climate change. Since MacArthur and Wilson first suggested their island biogeography theory, the concept of habitat networks has been further developed and evaluated. Networks have also been incorporated into a range of international and national policy and legislation.