ABSTRACT
Well-founded methods to assess habitat connectivity are essential to inform land management decisions that include conservation and restoration goals. Indeed, to be able to develop a conservation plan that maintains animal movement through a fragmented landscape, spatial locations of habitat and paths among them need to be represented. Graph-based approaches have been proposed to determine paths among habitats at various scales and dispersal movement distances, and balance data requirements with information content. Conventional graphs, however, do not explicitly maintain geographic reference, reducing communication capacity and utility of other geo-spatial information. We present spatial graphs as a unifying theory for applying graph-based methods in a geographic context. Spatial graphs integrate a geometric reference system that ties patches and paths to specific spatial locations and spatial dimensions. Arguably, the complete graph, with paths between every pair of patches, may be one of the most relevant graphs from an ecosystem perspective, but it poses challenges to compute, process and visualize. We developed Minimum Planar Graphs as a spatial generalization of Delaunay triangulations to provide a reasonable approximation of complete graphs that facilitates visualization and comprehension of the network of connections across landscapes. If, as some authors have suggested, the minimum spanning tree identifies the connectivity “backbone” of a landscape, then the Minimum Planar Graph identifies the connectivity “network”. We applied spatial graphs, and in particular the Minimum Planar Graph, to analyze woodland caribou habitat in Manitoba, Canada to support the establishment of a national park.
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ACKNOWLEDGEMENTS
This research was funded by Parks Canada Species at Risk Recovery Action and Education Fund, a program supported by the National Strategy for the Protection of Species at Risk and Parks Canada Western Canada Service Research Fund as well as GEIODE Strategic Initiative Program. Participating partners of this project were Manitoba Hydro, Manitoba Conservation, Tolko Ltd. and Natural Resources Institute of the University of Manitoba. We thank Jennifer Keeney for collating data and doing the GIS and mapping work. We also thank Richard Pither, Pasi Reunanen, Patrick James, Glenn Sutherland, Doug Steventon and two anonymous reviewers for helpful comments.
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Fall, A., Fortin, MJ., Manseau, M. et al. Spatial Graphs: Principles and Applications for Habitat Connectivity. Ecosystems 10, 448–461 (2007). https://doi.org/10.1007/s10021-007-9038-7
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DOI: https://doi.org/10.1007/s10021-007-9038-7