Landscape Ecology

, Volume 25, Issue 4, pp 519–532 | Cite as

The sensitivity of least-cost habitat graphs to relative cost surface values

  • Bronwyn RayfieldEmail author
  • Marie-Josée Fortin
  • Andrew Fall
Research Article


Maintaining and restoring connectivity among high-quality habitat patches is recognized as an important goal for the conservation of animal populations. To provide an efficient measure of potential connectivity pathways in heterogeneous landscapes, least-cost route analysis has been combined with graph-theoretical techniques. In this study we use spatially explicit least-cost habitat graphs to examine how matrix quality and spatial configuration influence assessments of habitat connectivity. We generated artificial landscapes comprised of three landcover types ranked consistently from low to high quality: inhospitable matrix, hospitable matrix, and habitat. We controlled the area and degree of fragmentation of each landcover in a factorial experiment for a total of 20 combinations replicated 100 times. In each landscape we compared eight sets of relative landcover qualities (cost values of 1 for habitat, between 1.5 and 150 for hospitable matrix, and 3–10,000 for inhospitable matrix). We found that the spatial location of least-cost routes was sensitive to differences in relative cost values assigned to landcover types and that the degree of sensitivity depended on the spatial structure of the landscape. Highest sensitivity was found in landscapes with fragmented habitat and between 20 and 50% hospitable matrix; sensitivity decreased as habitat fragmentation decreased and the amount of hospitable matrix increased. As a means of coping with this sensitivity, we propose identifying multiple low-cost routes between pairs of habitat patches that collectively delineate probable movement zones. These probable movement zones account for uncertainty in least-cost routes and may be more robust to variation in landcover cost values.


Habitat connectivity Least-cost Corridors Habitat resistance Fragmentation Graph-theory Effective distance Dispersal Habitat resistance Fragmentation 



We would like to thank Josie Hughes for assistance with the implementation of the placement algorithm used to create simulated maps. We are also grateful to Stephen Smith who was invaluable with data management and information technology services. Many thanks are extended to the researchers in LE Lab and especially to Patrick James for helpful discussions and valuable comments on drafts. Funding was generously provided by NSERC as a CGS to BR and an NSERC Discovery Grant to MJF.

Supplementary material

10980_2009_9436_MOESM1_ESM.tif (12.6 mb)
Appendix 1. Interaction plots for the fragmentation of habitat (H_FRAG) versus the set of relative cost values (C1–C8) plotted separately at each percentage of hospitable matrix (HM_COV; a–e). Mean values of the total spatial deviation of least-cost links is plotted for each of the cost sets at each level of H_FRAG (TIFF 12,949 kb)


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Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Bronwyn Rayfield
    • 1
    Email author
  • Marie-Josée Fortin
    • 1
  • Andrew Fall
    • 2
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoCanada
  2. 2.School of Resource and Environmental ManagementSimon Fraser UniversityBurnabyCanada

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