These ecological systems are always changing due to environmental factors.

Also bottle gardens can act as a closed ecological system.

That radiation has been associated with skin cancer and damage to ecological systems.

Disruptions in ecological systems are often the cause of disease.

In recent years, scientists have learned a lot more about how an ecological system works.

The forests, being an ecological system are subject to the species succession process.

The use of coal caused many environmental problems and changed the ecological system around the city.

Now the ecological system at the summit has collapsed, he said.

Fire is an important process that affects ecological systems across the globe.

These studies were early applications of energy concepts to ecological systems.