ABSTRACT
The term system is used in many different contexts. Reference is made, inter alia, to natural, organic, social, ideological, political, cultural, religious, administrative, legislative, monetary, urban-planning, industrial, agricultural, insurance, healthcare, education, power, and computer and communications systems. The scientific use of the term comes from physics, and more specifically from thermodynamics, where a system is defined as the portion of the universe that we are considering, in contrast to the environment, which is the rest of the universe. System state is a fundamental concept. The stability of the equilibrium points is analogous to the relief of a landscape with smooth terrain containing hills and depressions. Ecosystems are extremely complex systems, with a great number of internal and external interactions. The stability of an ecosystem is dependent on the constant, regular flow of energy and circulation of vital chemical substances through its structures.
