Springs—Groundwater-Borne Ecotones—A Typology, with an Overview on the Diversity of Photoautotrophs in Springs

This chapter briefly reviews the theoretical frameworks provided for springs across disciplines and scales (habitats, ecosystems, multiple ecotones etc.), and their unique properties and features (extreme heterogeneity, biodiversity hotspots, refugia, least-impaired habitat relicts, etc.). Special attention is devoted to a synthesis of the main classification approaches to springs, and to a succinct representation of the main kinds of springs. The chapter also offers an overview of the main groups of photoautotrops in springs, discussing their diversity, main characteristics, and environmental determinants. Finally, I acknowledge the highly endangered condition of spring habitats worldwide (silent global crisis of spring demise) discussing threats, and possible resilience, remediation, and restoration strategies.