Ecosystem Structure

Boundaries of Ecosystems Overlap and Change It is difficult to define the exact boundaries of an ecosystem. All ecosystems are connected to others around them. All ecosystems on the earth are connected to one another to form the biosphere. A change in the ecosystem may affect many others.

When one population is affected by abiotic factors, many others are in the same community are affected at the same time.

Most Communities Have More Producers than Consumers One of the most important abiotic factors that affects relationships in community is energy. Without the sun, there would be no green plants, no herbivores, and no carnivores. There are few ecosystems that get their energy from another source.

A communities size is limited by the amount of energy available for its producers. The gross primary productivity is the amount of chemical energy fixed by photosynthesis.

The flow of energy and the amount of mass in a community is like a pyramid. The loss of energy from a food chain can be represented by an energy pyramid. Each level of the pyramid has 1/10 of the energy of the level below it.

Only about 1/1,000 of the chemical energy used by producers can flow through a three- consumer food chain to a top predator. When humans eat they act as a top level consumers.