Student Worksheet

Activity Instructions

Students will...

You will understand the basic principles of ecosystem ecology, including tropic levels and interactions between biotic and abiotic elements
You will recognise the impact of bushfires on ecosystems and how ecosystems may recovers following a bushfire event
You will build their thinking and questioning skills.

Students can...

You can work independently to complete tasks
You can read and analyse an article
You can watch and analyse a clip
You can make connections between texts.

Part A: Read The Conversation Article Below

These plants and animals are now flourishing as life creeps back after bushfires. Kathryn Teare Ada Lambert, University of New England

The science of resprouting

Of course, bushfires kill innumerous trees – but many do survive. Most of us are familiar with the image of bright green sprouts shooting from the trunks and branches of trees such as eucalypts. But how do they revive so quickly?

The secret is a protected “bud bank” which lies behind thick bark, protected from the flames. These “epicormic” buds produce leaves, which enables the tree to photosynthesise – create sugar from the sun so the tree can survive.

Under normal conditions, hormones from shoots higher in the tree suppress these buds. But when the tree loses canopy leaves due to fire, drought or insect attack, the hormone levels drop, allowing the buds to sprout.

Insect influx

This summer’s fires left in their wake a mass of decaying animal carcasses, logs and tree trunks. While such a loss can be devastating for many species – particularly those that were already vulnerable – many insects thrive in these conditions.

For example, flies lay eggs in the animal carcasses; when the maggots hatch, the rotting flesh provides an ample food source. This process helps break down the animal’s body – reducing bacteria, disease and bad smells. Flies are important decomposers and their increased numbers also provide food for birds, reptiles and other species.

Similarly, beetles such as the grey furrowed rosechafer, whose grubs feed on decaying logs and tree trunks, add nutrients to the soil when they defecate which helps plants grow again.

Insects also benefit from the mass of new leaves on trunks and branches. For example, native psyllids – an insect similar to aphids – feed on the sap from leaves and so thrive on the fresh growth.

Animal carcasses are a sad consequence of bushfire, but provide a boon to some insect species. Sean Davey/AAP

Then come the birds

Once insects start to move back into an area from forested areas nearby, the birds that eat them will follow.

An increase in psyllids encourages honeyeaters – such as bell miners and noisy miners – to return. These birds are considered pests.

A CSIRO study after bushfires in Victoria’s East Gippsland in 1983 found several native bird species – flame and scarlet robins, the buff-rumped thornbill and superb fairy-wren – increased quickly to levels greater than before fire. As shrubs in the understorey regrow, other species will move in, slowly increasing biodiversity.

Since the recent bushfire in woodland near Moonbi in New South Wales, numerous bird species have returned. On a visit over this past weekend, I observed currawongs landing in the canopy, saw fairy wrens darting in and out of foliage sprouting from the ground, and heard peep wrens in tufts of foliage on bark and high branches.

Honeyeaters moved between burnt and intact trees on the edge of the blackened forest and butterflies visited new plants flowering after recent rain.

The presence of the currawong, while a pest species, shows birdlife is returning to the bush. Flickr, CC BY

Weeds can help

Weeds usually benefit when fire opens up the tree canopy and lets in light. While this has a downside – preventing native plants from regenerating – weeds can also provide cover for native animal species.

A study I co-authored in 2018 found highly invasive Lantana camara provided habitat for small mammals such as the brown rat in some forests. Mammal numbers in areas where lantana was present were greater than where it was absent.

Lantana often grows quickly after fire due to the increase in light and its ability to suppress other plant growth.

Lantana provides cover for animal species. Flickr, CC BY

Is there hope for threatened species?

Generalist species – those that thrive in a variety of environments – can adapt to burnt forest. But specialist species need particular features of an ecosystem to survive, and are far less resilient.

The critically endangered Leadbeater’s possum lives only in small pockets of forest in Victoria.

It requires large fires to create a specific habitat: big dead trees provide hollows for shelter and nesting, and insects feeding on burnt wood and carcasses provide a food source.

But for the Leadbeater’s possum to benefit from the fire regime, bushfires should be infrequent – perhaps every 75 years – allowing time for the forest to grow back. If fires are too frequent, larger trees will not have time to establish and hollows will not be created, causing the species’ numbers to decline.

Similarly in NSW, at least 50% and up to 80% of the habitat of threatened species such as the vulnerable rufous scrub-bird was burnt in the recent fires, an environmental department analysis found.

Looking ahead

Only time will tell whether biodiversity in these areas is forever damaged, or will return to its former state.

Large fires may benefit some native species but they also provide food and shelter for predatory species, such as feral cats and foxes. The newly open forest leaves many native mammals exposed, changing the foodweb, or feeding relationships, in an ecosystem.

This means we may see a change in the types of birds, reptiles and mammals found in forests after the fires. And if these areas don’t eventually return to their pre-fire state, these environments may be changed forever – and extinctions will be imminent.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Part B: Thought Starter: Can ecosystems only exist outdoors?

Step 1.

In your own words, describe what is meant by ‘ecosystem’.

Step 2.

Now, watch the following clip:

Step 3.

Complete the following questions in relation to the video:

1. What is ecosystem ecology?

2. Why is it hard to define an ecosystem?

3. How can an ecosystem be measured?

4. What is the relationship between food chains and trophic structure?

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Ecosystems After A Bushfire

Natural disasters such as bushfires, flooding or storms can be disasters for ecosystems. However, many organisms within an ecosystem have adaptations that help them respond and recover to these natural disasters. In Australia, we have the chance to witness this recovery following the recent bushfires.

The bushfires caused significant damage to a very large area; however, recovery is already evident. While many plants and animals suffered immensely through these fires, and numerous individual species have been pushed to the brink, looking at how a landscape recovers from a fire can help us to understand how ecosystems function and how energy flows through an ecosystem.

Part C: Article Analysis

Step 1.

Read the article again and answer the following questions.

1. Note down three things that you find interesting or important in this article:

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2. How does this article help you to understand ecosystems and the flow of energy through an ecosystem?

3. From reading this article, how would you summarise the impact of a bushfire on food chains and energy flow in an ecosystem?

4. What does this article make you think about humans can be managing landscapes after natural disasters?

Start A Conversation

Connect and collaborate with family, friends, neighbours or classmates.

What new ideas did you get that EXTENDED or pushed your thinking in new directions? Share these ideas with a friend, family member or classmate by sending them an email.

Taking It Further

What is still CHALLENGING or confusing for you to get your mind around? What question or puzzles do you now have?

Brainstorm these thoughts and ideas and create an actionable solution for each of them.

Bushfires and Ecosystems

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