Comparison of explanatory variables for boosted regression trees (BRT) models for four macroinvertebrate metrics at two spatial scales (Full Region and four Individual Ecoregions); variables are presented in descending order of variable relative importance (VRI) in each model.^*

*EPTR –Total taxa richness of Ephemeroptera, Plecoptera and Trichoptera; B–Soils with a moderate infiltration rate, C–Soils with a slow infiltration rate, D–Soils with a very slow infiltration rate, Rip –Riparian. See Table 1 for variable definitions.