Ecosystems emerging: 3. Openness

This fourth paper in the series on Ecosystems Emerging treats the propertie s of ecosystems derivable from the single elementary principle of openness. The paper also introduces the third law of thermodynamics and shows what c an be derived from this law for open systems. This leads to determined cond itions for ecosystems with complex organic molecules and living organisms w ith respect to inflow of low entropy energy and outflow of high entropy ene rgy and temperature range. Moreover, it can be shown that the through flow of exergy as estimated and reflected by ecological variables is both suffic ient and necessary for the formation of cycles and emerging properties of e cosystems. Finally, the circumstances under which the development of ecosys tems is limited by matter or energy is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.