ABSTRACT
This chapter provides grounds to identify ecoregions based on their environmental dimension. It presents how ecologists and physical geographers define so-called biomes, biogeographical provinces, bioregions, georegions, ecoregions or large ecosystems. The chapter points out how disciplines often focus on different components of the environment, thus defining ecoregions in different ways. It also highlights the importance of the definition of environmental regions for ecological continuity and the debate on tipping elements of the planetary system.
