ABSTRACT
Definitions of ecosystems may have differences among authors but generally all have three common properties that include the presence of biotic and abiotic components and their interactions. It is divided into many distinct functional units called ecosystems. The ecological pyramids represent the trophic structure and also trophic function of the ecosystem. Thus, communities of terrestrial ecosystems and shallow water ecosystems contain gradually sloping ecological pyramids because these producers remain large and characterized by an accumulation of organic matter. In such aquatic ecosystems as lakes and open sea, primary production is concentrated in the microscopic algae. Aquatic ecosystem consists of marine and fresh water and estuary ecosystem. Terrestrial ecosystem consists of forest, grassland, desert and cropland ecosystem. Ecosystems are capable of maintaining their state of equilibrium. They can regulate their own species structure and functional processes.
