Productivity of ecosystems is the energy flow between trophic (feeding) levels of an ecosystem. Primary productivity is that made from sunlight by photosynthesis. The energy flow between trophic levels limits the food available. Ecosystem productivity changes can be caused by the seasons, disturbances, and biological diversity. — Ecosystems are complex dynamic systems made up of living organisms, their interactions, and their physical environment. These are the plants, animals that eat them and animals that prey on others, together with the soil and rainfall on which they all depend. …