School › Ecosystems › Ages 10–11
How an ecosystem works
Biotic and abiotic factors, producers and consumers, and what happened when wolves returned to Yellowstone. Then build a sealed bottle ecosystem and watch it recycle its own water.
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An ecosystem is an area where plants, animals and other organisms, together with the weather and landscape, work together. It has biotic (living) factors such as plants and animals, and abiotic (non-living) factors such as rocks, temperature and humidity.[1]
The Sun is the first source of energy for almost every ecosystem. Producers, mostly plants on land and phytoplankton in the ocean, make their own food from sunlight. Consumers cannot make their own food and must eat other organisms.[2]
Decomposers break down waste and dead matter. Every part of an ecosystem depends on every other part, directly or indirectly.[2][1]
Abiotic changes affect living things: a change in temperature can change which plants grow, and the animals that depend on those plants must adapt, move to another ecosystem or die.[1]
When wolves returned to Yellowstone National Park in the USA, elk became scarce where the wolves were. Willows, cottonwoods and aspens grew back, and the willows helped beavers and birds such as yellow warblers. One change spread through the whole ecosystem.[4]
Some animals are called keystone species: without them, the ecosystem would be very different or might not exist at all. Damaged ecosystems can sometimes be restored.[1]
Try it: A sealed bottle ecosystem
You need
- A large clear jar or plastic bottle with a lid
- Washed gravel
- Potting compost
- 2–3 small plants such as moss, small ferns or small leafy houseplants
- A spoon and a spray bottle of water
- Observation diary
Safety
Use a plastic bottle or have an adult handle glass jars. Wear gloves when handling compost and wash your hands afterwards. Keep the jar out of direct sun and away from heaters. Do not add animals to the jar.
What to do
- Put a layer of washed gravel in the bottom of the jar for drainage.
- Add potting compost on top, deep enough for the plant roots.
- Plant the small plants and moss and press the compost down gently.
- Spray a little water, then close the lid.
- Place the jar in bright light but not in direct sunshine or near a radiator.
- Look twice a week for 4 weeks: is there condensation on the glass? Are the plants growing? Record what you see.
- Decide which parts of your bottle ecosystem are biotic and which are abiotic.
What happens, and why?
Your jar is a small model of an ecosystem. In a sealed container the water evaporates, condenses on the glass and runs back down, so it is recycled and hardly ever needs watering. Light condensation shows there is just enough water. The plants are the producers: they need light from outside, which is why the jar must stand somewhere bright.[5][2]
Play: Producer, consumer or abiotic?
Is this a producer, a consumer, or a non-living (abiotic) factor?
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Quiz
Other ages: Ages 6–7 · Ages 15–16