Barren Lands
Barren Lands are extensive areas with little to no vegetation. Abiotic substrate features dominate the landscapes. What little vegetation that does exist is generally restricted to areas of concentrated resources (total vegetation cover is typically less than 10%) and composed of species that are highly adapted to severely arid conditions. Barren lands, also called deserts under some definitions, have developed for a multitude of reasons. For example, the Sahara Desert is believed to have been a tropical woodland system with a plethora lakes and rivers up until the end of the Pleistocene at which point an extreme warming-drying trend occurred (between 7000 and 3500 BP) putting the Sahara in a desolate state (1). Humans have also historically affected alterations in vegetation cover. Archeological findings indicate that barren pans near the Atacama Desert were once forested areas, but over-harvesting altered the microclimates of the basins pre-European settlement.