Principal component and Bray and Curtis ordination techniques were used to explore the ecology of lichen–moss ground-layer communities in Ontario and Wisconsin. The Ontario data included thirty-nine 100-m2stands from a large geographic region; lichen and moss relations along macroscale environmental and successional gradients were considered. Species relations along gradients of moisture and exposure were recognized. The Wisconsin data included one hundred sixty-six 0.5-m2quadrats from a single site in the Wisconsin Pine Barrens; species relations along microscale environmental gradients were examined. Gradients related to moisture, light, and temperature regimes were recognized. The ordinations provided a graphic display of the ground-layer lichen–moss community ecology and offered a basis for further work on the comparative autoecology of variousCladonialichens.Cladonia mitis, C. rangiferina, andC. uncialis, the subject of a subsequent paper in this series, were found to be similar in the macroscale but separated in the microscale ordinations.