Why do all ecosystems depend on producers?

Definition of ecosystem   The term ecosystem (system environment), has been proposed for the first time dall'ecologo English George Tansley in 1935, but the idea of the concept of ecosystem as a whole between organisms and the environment dates back to ancient times, even if only in the twentieth century has entered the official scientific jargon.   An ecosystem consists of the set of all living things that are found in a given physico-chemical environment, and the mutual relations that exist between both of them and between them and the environment surroundings, and who maintain a balance and homeostasis in time through the continuous exchange of matter and energy.   All environmental factors of physical-chemical nature that characterize an ecosystem, such as the temperature, pH, the concentration of mineral salts, the amount of light, oxygen and carbon dioxide available are the abiotic components. In this part of inanimate called "biotope" accommodates the living community consists of all the biotic components; they are formed from plant species,animals and microorganisms and are known collectively as the "biotic". It is, therefore, an association of organic that is created mainly because of particular climatic conditions, soil, hydrology present in a given geographical area, the habitat, which acts as the "active support" for the community living (biotic).

4) repetitive change