<meta http-equiv="refresh" content="1; url=/nojavascript/"> Ecosystems | CK-12 Foundation
Skip Navigation
You are reading an older version of this FlexBook® textbook: CK-12 Life Science Concepts For Middle School Go to the latest version.

12.10: Ecosystems

Difficulty Level: At Grade Created by: CK-12
Practice Ecosystems
Practice Now

What nonliving things are essential for life?

Living organisms cannot exist without the nonliving aspects of the environment. For example: air, water, and sunlight, which are all nonliving, are all essential to living organisms. Both nonliving and living things make up an ecosystem.

What is an Ecosystem?

Ecology is the study of ecosystems. That is, ecology is the study of how living organisms interact with each other and with the nonliving part of their environment. An ecosystem consists of all the nonliving factors and living organisms interacting in the same habitat . Recall that living organisms are biotic factors . The biotic factors of an ecosystem include all the populations in a habitat, such as all the species of plants, animals, and fungi, as well as all the micro-organisms. Also recall that the nonliving factors are called abiotic factors . Abiotic factors include temperature, water, soil, and air.

You can find an ecosystem in a large body of freshwater or in a small aquarium. You can find an ecosystem in a large thriving forest or in a small piece of dead wood. Examples of ecosystems are as diverse as the rainforest, the savanna, the tundra, or the desert ( Figure below ). The differences in the abiotic factors, such as differences in temperature, rainfall, and soil quality, found in these areas greatly contribute to the differences seen in these ecosystems. Ecosystems can include well known sites, such as the Great Barrier Reef off the coast of Australia and the Greater Yellowstone Ecosystem of Yellowstone National Park, which actually includes a few different ecosystems, some with geothermal features, such as Old Faithful geyser.

An example of a desert ecosystem in Baja California, showing Saguaro cacti.

Ecosystems need energy. Many ecosystems get their energy in the form of sunlight, which enters the ecosystem through photosynthesis . This energy then flows through the ecosystem, passed from producers to consumers . Matter is also recycled in ecosystems. Biogeochemical cycles recycle nutrients, like carbon and nitrogen, so they are always available. These nutrients are used over and over again by organisms. Water is also continuously recycled. The flow of energy and the recycling of nutrients and water are examples of the interactions between organisms and the interactions between the biotic and abiotic factors of an ecosystem.


  • abiotic factor : Nonliving aspect of the environment.
  • biogeochemical cycle : Pathway of elements like carbon and nitrogen through the non-living and living parts of the ecosystem.
  • biotic factor : Living aspects of the environment.
  • consumer : Organism that must eat or consume other organisms to obtain energy and nutrients.
  • ecology : Study of how living organisms interact with each other and with their environment.
  • ecosystem : All of the living things and non-living things interacting in the same area.
  • habitat : Ecological or environmental area where a particular species live.
  • photosynthesis : Process by which specific organisms (including all plants) use the sun's energy to make their own food from carbon dioxide and water; process that converts the energy of the sun, or solar energy, into carbohydrates, a type of chemical energy.
  • population : Group of organisms belonging to the same species that live in the same area and interact with one another.
  • producer : Organism that can absorb the energy of the sun and convert it into food through the process of photosynthesis; i.e. plants and algae.


  • An ecosystem consists of all the living things and nonliving things interacting in the same area.
  • Matter is also recycled in ecosystems; recycling of nutrients is important so they can always be available


Use the resource below to answer the questions that follow.

  1. How do land plants generate the energy they need for their metabolic energy? What do they do with excess energy? Where does this energy go?
  2. Where do scavengers in an ecosystem obtain their energy from? How can scavenging be a beneficial strategy for an organism?
  3. Given that some areas at high latitudes go days or months without sunlight, how applicable do you think is the statement that light is never a limiting resource? Explain your thinking fully.
  4. What do you think the relationship is between the total mass of carbon in a system and the total amount of biomass which can be generated in the ecosystem? What kind of problems can you foresee if every speck of carbon were turned into biomass? How long do you think a system like this would be stable? Explain your thinking.


  1. Define an ecosystem.
  2. Distinguish between abiotic and biotic factors.

Image Attributions


Difficulty Level:

At Grade

Concept Nodes:


7 , 8

Date Created:

Nov 29, 2012

Last Modified:

Nov 04, 2014
Files can only be attached to the latest version of Modality


Please wait...
Please wait...
Image Detail
Sizes: Medium | Original

Original text