Assessing functional connectivity: a landscape approach for handling multiple ecological requirements
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- The improvement of tools for protecting biodiversity requires integrating habitat connectivity to build efficient ecological networks that facilitate the movement of species under pressure from global change. Several methodological and scientific challenges are faced in constructing such networks. First, ecological networks need to incorporate habitat connectivity for species with different ecological requirements. Secondly, the networks should be based on functional connectivity rather than on structural connectivity alone. Thirdly, connectivity needs to be treated as a continuous variable.
- We propose a non-oriented approach of landscape description to identify favourable areas and measure functional connectivity for multi-specific applications, using three groups of common bird species (farmland specialists, forest specialists and generalists) as indicators of biodiversity.
- In the highly anthropized region of Seine-et-Marne, we defined 20 landscape types based on composition and configuration. We used statistical modelling to obtain a value of favourability for each landscape type for each bird group. We then mapped landscape favourability, for the three groups in 1982 and 2003 to identify favourable entities (adjacent favourable landscape units) and determine connectivity. We then examined temporal changes in the favourable areas and their connectivity and determined the sensitivity of the favourable landscape types to land cover change.
- Composition and configuration both influenced landscape favourability. Some landscape types were favourable for several groups of species and could potentially serve as junction landscapes in ecological networks that accommodate a variety of ecological requirements. Increasing urbanization and fragmentation between 1982 and 2003 resulted in a decrease in favourable landscape units, as well as consequent decreases in favourable areas and connectivity, for the three species groups. Connectivity loss was greatest for farmland and generalist species, as it was already high for forest species in 1982.
- Such a non-oriented landscape description could be used to delineate multi-specific ecological networks at regional and national scales and could be further developed to study the connectivity of communities. The maps of favourability produced here could also be used in combination with other methods, such as graphs or circuits, to detect ecological corridors and stepping stones to habitat connectivity.