Ecosystem

1. An ecological community forming a unit with its environment. For example, an organism and its environment or an organization and its environment.

2. A biological community including not only the plants of which it is composed, but the animals habitually associated with them, and also the physical and chemical components of the immediate environment or habitat in which the community exists. These together form a recognizable self-contained entity with definable boundaries. Any such community is however part of a larger physical and biological system.

3. The totality or pattern of relations between organisms and their environment, understanding of which permits explanation of empirical observations such as growth, differentiation, order, and dominance in biological evolution.

4. Man has changed from being a simple component of individual ecosystems to becoming a dominant force and link in the larger system, which (through technology and the development of urban systems) ties together all ecosystems in a higher (global) level of organization comprising the entire biosphere.