Connectivity and ecological networks

Isolation and connectivity are essential spatial characteristics of natural ecosystems and essential for species in fragmented landscapes. In these landscapes natural habitats have the characteristics of islands. There are processes of colonization by species and there is extinction. The metapopulation theory models the metapopulations that consist of a number of connected subpopulations. They act as a network of subpopulations. Human land use and land cover change has led to fragmentation of the terrestrial landscape. Forests became isolated islands, grass steppes got fragmented and the river continuum blocked in many cases by dams. This caused wildlife populations to get isolated and act as metapopulations. Habitat patches get empty as they are too small for survival of the species populations in it. To mitigate isolation and let the subpopulations of these terrestrial habitat islands function as one metapopulation ecological networks should be established. Already in the 1980s and 1990s this was understood and globally initiatives have been started from both grass root organizations and public authorities. This made nature conservation change from isolated site protection to an ecosystem approach placing protected areas in a coherent ecological network. This also included initiatives for developing technical solutions such as wildlife bridges and removal of dams in rivers. The importance of connectivity through ecological corridors is now also established in the 2020 targets of the Convention of Biological Diversity.