Biodiversity conservation and the identification of areas that need to be linked.

Linking like with like: optimising connectivity between environmentally-similar habitats

Diogo Alagador, Maria Triviño, Jorge Orestes Cerdeira, Raul Brás, Mar Cabeza and Miguel Bastos Araújo

LANDSCAPE ECOLOGY, Published online 10^th January 2012

With human population burgeoning habitat fragmentation is increasingly becoming a threat to biodiversity. The best way to overcome the problem is to ensure connectivity between o isolated habitats. However, the identification of linkages favoring connectivity is not as easy as it sounds. Firstly, they compete with other land uses which means they need to be cost-efficient. Secondly, linkages for one species might be counterproductive for others, which mean they should effectively account for distinct mobility requirements. Thirdly, detailed information on the auto-ecology of most of the species is lacking, so linkages may have to be defined based on surrogates.

In order to address the challenges enumerated above the researchers of this paper developed a framework that (a) identifies environmentally-similar habitats; (b) identifies environmental barriers (i.e., regions with a very distinct environment from the areas to be linked), and; (c) determines cost-efficient linkages between environmentally-similar habitats, free from environmental barriers.

It is assumed that species with similar ecological requirements occupy the same environments, so environmental similarity provides a rationale for the identification of the areas that need to be linked. The researchers used a variant of the classical minimum Steiner tree problem in graphs to address c). They present a heuristic for this problem that is capable of handling large datasets.

To illustrate the framework, the researchers identify linkages between environmentally-similar protected areas in the Iberian Peninsula. The Natura 2000 network is used as a positive ‘attractor’ of links while the human footprint is used as ‘repellent’ of links. They compare the outcomes of their approach with cost-efficient networks linking protected areas that disregard the effect of environmental barriers. The researchers say as expected, the latter achieved a smaller area covered with linkages, but with barriers that can significantly reduce the permeability of the landscape for the dispersal of some species.