What is Ecosystem, biotope, community?

An ecosystem is the set of organisms living in a defined place together with the physical environment they occupy and exchange with: the community (or biocoenosis) — all the populations of all the species — and the biotope — the soil, water, air, light and climate. Its boundaries are chosen for the question: a rotting log, a pond, a forest, an ocean basin, the whole biosphere. An ecosystem is an open system (Chapter 1): energy flows through it, matter cycles within it and across its borders, and its structure is the pattern of who eats whom.