ABSTRACT
The ecosystem is a core concept in the fields of biology and ecology, serving as the level of biological organization in which organisms interact with each other and with their immediate environment. Ecosystems are defined by interactions among living organisms, dead organic matter, and abiotic environments such that system-level processes emerge, including the one-way flow of energy, the cycling of elements. All ecosystems are “open systems” requiring a net flow of energy to persist over time. Human alteration of ecosystems is now pervasive globally, and ecologists are increasingly integrating human social processes into ecosystem science at many levels.
