Fig. 4. Comparison of (A) the Wilderness Areas map by McCloskey and Spalding (1989); (B) Frontier Forests map by Bryant et al. (1997); (C) Intact areas map produced on the base of the Human Footprint data set by Sanderson et al. (2002), and (D) IFL mapping results for different regions: I – Tropical Africa; II – Amazon basin; III – Canadian province Alberta.; Intact areas (green); the rest of forest zone (gray).