Relative importances for predictors of butterfly species richness, butterfly composition (principal curve score), and butterfly density as determined by boosted regression tree analysis, using procedure gbm.step [52, 53].

Importances with daggers (†) are associated with predictors that were not included in a simplified model (as determined by gbm.simplify). Ten-fold cross-validated correlation between observed and predicted response are shown at the bottom for full and simplified models as well as squared correlation for full model. Model represents predictions for individual surveys (n = 21 surveys per site) across 25 sites (total n = 525).