The basic unit of study in environmental science is the ecosystem. An ecosystem consists of a biological community and its physical environment. Here are the most important things you need to know about ecosystems:

  • An ecosystem can be as small as a drop of water or as large as a forest.

  • Some ecosystems (such as caves) have clear boundaries, while others (such as forests) do not.

  • An ecosystem provides the organisms that live in it what they need to survive: food (energy), water, and shelter.

  • All the biological processes in an ecosystem run on energy captured from the sun.

  • Energy moves around an ecosystem through the food web.

  • The number of producers (or plants) in an ecosystem determines that ecosystem’s productivity potential.

  • An ecosystem recycles matter through the process of decomposition.

  • Ecosystems provide services, such as food production (farmland), water filtering (wetlands), carbon removal, raw material production (timber, rubber), and aesthetic value.

  • Because many modern human societies get their food, water, and other resources from all over the planet, you can consider the entire globe to be the human ecosystem.