Mean (± s.e.) pairwise costs of dispersal between sites within each core and peripheral region for each landscape variable (Chilliwack Valley = CV; South Cascades = SC; Willapa Hills = WH).

Ecological justification for each variable is presented with supporting references referring to Dicamptodon or other amphibians. The predicted direction of dispersal resistance for increasing values of each variable is indicated where ‘+’ = greater resistance, and ‘−’ = less resistance. n = sample size of populations.*areas covered by non-forested, naturally occurring landscape features (e.g. shrub land, grass land, rock);**barriers were defined as developed land, open water and perennial ice.