This eBook contains five chapters from the larger work Understanding Physical Chapter 26: Introduction to Life; Chapter 27: Spatial Distribution of Species and Ecosystems; Chapter 28: Biogeochemical Cycling and Ecosystem Productivity; Chapter 29: Soils and Soil Classification; and Chapter 30: Human Alteration of the Biosphere. This eBook was written for students taking introductory Physical Geography taught at a college or university. The author of this eBook, Michael Pidwirny, is an Associate Professor in the Department of Earth, Environmental and Geographic Science at the University of British Columbia, Okanagan Campus, located in Kelowna, British Columbia, Canada. Michael teaches courses in Physical Geography, Environmental Science, Anthropogenic Climate Change, and Statistical Analysis in Earth Science and Geography. He is extremely interested in the use of computer technology to enhance the learning experience of students. Michael's main research interest deals with the analysis of historical and simulation model climate data to determine how human caused climate change will influence North American and European ski resorts.