The biosphere and the role of vegetation
'Vegetation' signifies palatable plants to a pastoral farmer, commercially important trees to a forester, diverse textures to an artist, and valued species to a conservationist. To a geographer, the vegetation cover of an area is a three-dimensional, organised, dynamic, and functional aggregation of living things that protects soil and rocks from acce lerated erosion, moderates the flow of water into streams, provides shelter to people and their livestock, tempers local climates, enhances visual appearance, fosters feelings of identity with place, creates opportunities for recreation, records past human activities and extreme environmental events, mops up atmospheric carbon dioxide, and affects albedo. In this chapter, vegetation will be discussed from a biogeographic stance, with particular emphasis on geographic patterns of plants and how they have changed over historic and geologic time. There will also be reference to such ecological concerns as the growth regimes and functional relations of plant species. As in other areas of physical geography, vegetation studies are guided by abstract ideas, models, and theories. They will be introduced as appropriate.