Year 8 Science · Unit 1 · Lesson 21
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Learning Goals
Scenario, Daintree Rainforest without decomposers
The Daintree Rainforest in far north Queensland is one of the oldest tropical rainforests on Earth, estimated to be over 135 million years old. It supports thousands of species of plants, animals, fungi and bacteria. Decomposers, primarily bacteria and fungi, constantly break down fallen leaves, dead wood, and the bodies of dead animals, releasing nutrients back into the thin rainforest soils. Scientists estimate that without this constant recycling, the rainforest's soil would become nutrient-depleted within years.
(a) If all decomposers were suddenly removed from the Daintree Rainforest, predict what would happen to nutrient cycling and plant growth within 10 years. Use the words "nutrient," "soil," and "producer" in your answer.
(b) Explain how the removal of decomposers would eventually affect consumers in the Daintree. Trace the chain from decomposer loss → soil → producers → consumers.
Compare two
Complete the table to compare Producers, Consumers, and Decomposers. Use specific Australian examples where possible.
| Feature | Producer | Consumer | Decomposer |
|---|---|---|---|
| Energy source | |||
| Australian example | |||
| Role in ecosystem | |||
| Effect on nutrients | |||
| Effect if removed from ecosystem |
1. A student says: "Decomposers are the least important role in an ecosystem because they only eat things that are already dead." Do you agree or disagree? Justify your answer using at least two pieces of evidence from the lesson.
2. Sunlight is an abiotic factor, but it affects every living role in an ecosystem. Trace how sunlight energy flows from the sun through a producer, to a consumer, and finally to a decomposer in the Great Barrier Reef.
Wrap Up
In one sentence, why does every ecological role (producer, consumer, decomposer) depend on the other two?