The Coupling of Carbon and Ion Cycles Including N, P and S in Soils of Terrestrial Ecosystems

Abstract

The coupling of element cycles in terrestrial ecosystems is governed by the activities of organisms, both plants and soil organisms. For chemical elements like nutrients organisms act as sinks or sources, taking up or releasing the chemical elements as neutral compounds (CO₂, O₂, H₂O) or ions. The soil represents the reaction vessel, from which ions are taken up or into which they are released. The function of organisms as sinks and sources for ions has the result that the cycles are governed by the activity of the organisms. The soil modifies the cycles by providing storage capacities of different binding form and binding strength, and by releasing some chemical elements by weathering. The coupling of carbon and ion cycles in soil is therefore treated in an ecosystem context. The time scale of ecosystem processes governing the element cycles covers decades to centuries or even millennia. In the context of the 1991 NATO conference, ecosystem processes describing storage changes in the ecosystem were of main concern. The aspects of biochemical and chemical reactions in soil which are involved in the cycles are not discussed; these are covered in many textbooks.