Contents Foreword..................................................................................................................................................4 Acknowledgment.................................................................................................................................... 5 Chapter 1: Introduction.............................................................................................................. 10 1.1.1 Being an algae: one of the oldest jobs on Earth................................................................13 1.1.2 Lichens: you better make it together................................................................................. 17 1.2 If it all comes together: biological soil crusts.....................................................................19 1.3 Survival experts: how to conquer everything..................................................................... 22 1.4 Life at its edge: cryptogams as cosmopolitan extremophiles............................................ 26 1.5 Hidden diversity: microhabitats and biogeography..........................................................29 1.6 Projects and sites of this thesis............................................................................................. 33 1.6.1 The Arctic, Antarctic and European Alpine sites.............................................................36 1.6.2 The precipitation gradient along the Chilean Cordillera.................................................38 1.6.3 The Atacama Desert...........................................................................................................40 1.7 Aims and course of this thesis............................................................................................. 43 Chapter 2: Biodiversity Coldspot: structure and richness of Arctic, Antarctic and European Alpine biocrusts....................................................................................................................................46 Uncovering biological soil crusts: carbon content and structure of intact Arctic, Antarctic and alpine biological soil crusts..................................................................................................................47 Genus richness of microalgae and Cyanobacteria in biological soil crusts from Svalbard and Livingston Island: morphological versus molecular approaches.....................................................61 Strong in combination: Polyphasic approach enhances arguments for cold-assigned cyanobacterial endemism.................................................................................................................... 78 Assessing recovery of biological soil crusts across a latitudinal gradient in Western Europe.......94 Chapter 3: Precipitation gradient of the Chilean Coastal Cordillera: variability and geochemical cycling of biocrusts........................................................................................................ 108 Pedogenic and microbial interrelations to regional climate and local topography: New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile............................. 109 Biological soil crusts along a climatic gradient in Chile: Richness and imprints of phototrophic microorganisms in phosphorus biogeochemical cycling................................................................. 132 7 Chapter 4: Sophisticated systems: ecological niches of cryptogams in the Atacama Desert and their adaptations..........................................................................................................................149 A Case Study on Fog/Low Stratus Occurrence at Las Lomitas, Atacama Desert (Chile) as a Water Source for Biological Soil Crusts....................................................................................................... 150 Distinct Refugia: edaphic and lithic cyanobacterial communities of the Atacama Desert...........168 Estimating Net Photosynthesis of Biological Soil Crusts in the Atacama Using Hyperspectral Remote Sensing.................................................................................................................................... 219 Desert breath - the Atacama Desert's unexpected living skin.........................................................238 Chapter 5: Synthesis..................................................................................................................265 5.1 Microhabitats matter......................................................................................................................266 5.2 Diversity patterns of functional groups.......................................................................................270 5.3 Biogeography of cyanobacteria.................................................................................................... 275 6. Outlook.................................................................................................................................. 279 7. Summary............................................................................................................................... 281 8. References..............................................................................................................................283 9. Appendix............................................................................................................................... 290 9.1 Scientific comic: Uncovering the Earth's skin............................................................................. 290 9.2 Cyanobacterial micrographs......................................................................................................... 294 9.3 Curriculum Vitae............................................................................................................................296 9.4 Declaration..................................................................................................................................... 298 8.