A Ecosystem is a set of at least two (autonomous) parties (the members of the ecosystem) whose individual work complements that of other members, and is of benefit to the set as a whole.
An ecosystem is distinct from a community in the sense that it is not (necessarily) an organization that (actively) facilitates the cooperation between its members. A community is considered a specialization of the more generic 'ecosystem' concept.
The purpose of forming, or being part of an ecosystem, is that a party can focus on a specific topic area, rely on others to provide for its needs, and being appreciated for the value of its own work as it provides for the needs of others.
A Ecosystem is a set of at least two (autonomous) parties whose individual work complements that of others, and is of benefit to the set as a whole.