Landscape Ecology

, Volume 22, Issue 8, pp 1155–1168

Testing assumptions of cost surface analysis—a tool for invasive species management

Research Article

DOI: 10.1007/s10980-007-9106-6

Cite this article as:
Gonzales, E.K. & Gergel, S.E. Landscape Ecol (2007) 22: 1155. doi:10.1007/s10980-007-9106-6


Applied ecology could benefit from new tools that identify potential movement pathways of invasive species, particularly where data are sparse. Cost surface analysis (CSA) estimates the permeability (friction) across a landscape and can be applied to dispersal modelling. Increasingly used in a diversity of applications, several fundamental assumptions that might influence the outputs of CSA (cost surfaces and least-cost pathways) have yet to be systematically examined. Thus, we explore two issues: the presumed relationship between habitat preferences and dispersal behaviour as well as the degree of landscape fragmentation through which an organism moves by modelling a total of 18 sensitivity and dispersal scenarios. We explored the effect of fragmentation by altering the friction values (generally assigned using expert opinion) associated with patch and linear features. We compared these sensitivity scenarios in two sites that differed in fragmentation. We also used eastern grey squirrels (Sciurus carolinensis) as an example invading species and compared diffusion models and two contrasting cost surface dispersal scenarios. The diffusion model underestimated spread because squirrels did not move randomly through the landscape. Despite contrasting assumptions regarding dispersal behaviour, the two cost surfaces were strikingly similar while the least-cost paths differed. Furthermore, while the cost surfaces were insensitive to changes in friction values for linear features, they were sensitive to assumptions made for patch features. Our results suggest that movement in fragmented landscapes may be more sensitive to assumptions regarding friction values than contiguous landscapes. Thus, the reliability of CSA may depend not only on the range of friction values used for patches but also the degree of contiguity in the landscape.


Canada Dispersal Exotic GIS Least-cost pathway Non-native Sciurus carolinensis Spatial models Squirrel Weighted surface 

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  1. 1.Integrative BiologyUniversity of GuelphGuelphCanada
  2. 2.Forest Sciences, Centre for Applied Conservation Research University of British ColumbiaVancouverCanada

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