ABSTRACT
A 1 m tree that was planted more than 30 years ago may today be more than 30 m tall. It has increased the biomass many times and there may be more than a thousand times as many leaves today on the tree during the summer than 30 years ago. When we follow the development of an ecosystem over a longer period or during a couple of spring months, we are witness to one of the many wonders in nature: An inconceivably complex system is developing and growing in front of us. What makes this development of complex (and beautiful) systems in nature possible? In accordance with the classic thermodynamics, all isolated systems will move toward thermodynamic equilibrium. All the gradients and structures in the system will be eliminated and a homogenous dead system will be the ‰nal result, and the content of eco-exergy or free energy will be zero. As work capacity (eco-exergy) is a result of gradients in certain intensive variables such as the temperature, pressure, chemical potential, etc., a system at thermodynamic equilibrium will have no ability to do work. But trees and plants are moving in opposite directions. ey are moving away from thermodynamic equilibrium at a faster and faster rate every year. We have already explained how this is possible. It is not a violation of the second law of thermodynamics, but the system is open and receives free energy from outside (mainly from solar radiation), and the free energy is used to maintain the system far from thermodynamic equilibrium. e openness is therefore an absolutely necessary condition for ecosystems. If they were not open, they would inevitably decompose to inorganic matter and would inexorably reach thermodynamic equilibrium.
