Learn what an ecosystem is, how matter and energy move through it, and what makes it stable. Most important points An ecosystem is composed of a community of organisms with their physical environment. Ecosystems can be of different sizes; can be marine, aquatic or terrestrial. The general categories of terrestrial ecosystems are known as biomes . In ecosystems, both matter and energy are conserved . Energy flows through the system, usually from light to heat, and matter is recycled. Ecosystems with greater diversity tend to be more stable, with greater resilience and resilience in the face of disturbances or damaging events. Introduction What do the tidal pools on the California coast and the Amazon rainforest in South America have in common? Despite the various orders of magnitude in size between them, they are both examples of ecosystems : co...