The classical concept of ecosystems and natural systems functioning generally stems from the idea of nature balance which underlines the stable state of ecological systems and where natural systems are taken as more or less closed and self-regulating ones. Both conception and strategies for classical nature conservation as well as environmental technologies are based on this equilibrium paradigm aiming at preservation of the temporary state and/or restoration of the so-called original state. But recently a new paradigm has been pushed (non-equilibrium paradigm) through which adjudges more importance to events and facts that are likely (stochastic), distinguishes episodic phenomena (e. g. natural catastrophes), stresses on openness of ecological systems, and multiple (as for situation and type are concerned) regulation, variability and heterogeneity of environment. In the nature, there appear, naturally, non-stable communities.