Modeling Connectivity of the Whole: A Graph Theoretic Application in Conservation Planning Prioritization

Abstract

This work aims to guide conservation prioritization by identifying areas of conservation critical to achieving an interconnected Arizonan landscape. A landscape connectivity assessment conducted with this goal in mind resulted in the identification of Important Connectivity Zones (ICZs) throughout the state. The assessment used graph theoretic and shortest-path betweenness centrality spatial modeling methods to evaluate structural connectivity with landscape integrity data as a permeability surrogate. The analysis yielded a landscape lattice comprised of 382,740 hexagonal nodes, each 100 hectares in size. Selection of nodes that exhibited the greatest cumulative facilitation of ecological flows throughout the entire landscape lattice resulted in the delineation of ICZs. The ICZ network constitutes a series of ‘wildways’ comprised of highly natural zones contributing the most to the connectivity of the entire landscape. The ICZs identified here may serve as a potential blueprint for guiding statewide connectivity efforts as well as informing future conservation action, land management, and planning efforts. Additionally, as ICZs include a metric quantifying their relative importance, this analysis provides a framework upon which local and fine-scale linkage designs can be evaluated within the context of the entire landscape. Such an evaluation may prove useful in identifying locations where fine-scale linkage designs are needed, ranking their relative contribution to connectivity of the whole, and prioritizing their implementation throughout the state.