The Structure of the Biosphere

Definitions of the biosphere’s boundaries have differed. Sometimes the biosphere is defined as a zone where both living organisms and the products of their activities are found. In this case the boundaries of the biosphere are quite vague: the oxygen molecules created by autotrophic plants reach the upper limits of the atmosphere, the position of which can only roughly be determined. Moreover, another product of autotrophic plants, organic carbon, can be carried by vertical tectonic movements from the Earth’s surface to considerable depths which are difficult to ascertain precisely. An alternative definition is one that reduces the biosphere to the totality of living organisms. In this case biosphere becomes a synonym of the term ‘biota’.