In the Classroom

Disturbing our Ecosystem

The interaction between elements in an ecosystem creates a dependency of one upon another. A slight change in one feature can disturb many others.

The introduction of a non-native species, for example, may reduce the number of native species, either by killing them (cats and cane toads), or by outcompeting them for food (sheep and rabbits), or by destroying native habitat (farm animals at water holes). The lost species will have had important roles in the environment before the introduced animals arrived; they will have provided food for others; thus, their loss will have impacts further along the food chain.

Activity

Demonstrate the Effect of Disturbance to the Ecogram:

Students construct flow charts. Two activities demonstrate disturbances and may serve for dismantling the ecogram.

Feral cat in their ecosystem

Introduce students to the feral cat IN: https://pestsmart.org.au/toolkit-resource/feral-cats-in-australia/

• Feral cats will eat all the animals, and some invertebrates: remove birds, lizards, some invertebrates (trees, litter, and seeds are left.)

• 45% of Australian plants are pollinated by animals: remove half the number of plants.

• Leaf litter will diminish, exposing the remaining invertebrates to be eaten by the cats: remove half the leaf litter and all of the invertebrates.

• Seed production will fail because insects and birds (eaten by cats) no longer pollinate: remove the remaining trees.

• Wind will blow away the remaining litter: remove the last of the litter.

Failure of pollination by insects

There has been an alarming loss of insects worldwide, caused by their exposure to insecticides resulting from increased land use by humans (3, 4). Beekeepers in America and Europe are losing 30 to 40% of their bee colonies every year. This is a serious threat to agriculturalists, as well as to native plants that are pollinated by insects. A loss of native plants affects those animals that depend on them for food, and the decline in those animals affects the food chain further along.

• Without pollination, there will be no seeds: remove seeds and seed cases (nuts, cones, pods)

• Without seeds, there will be no food for granivores: remove cockatoos

• Without seeds, no new trees will grow: remove trees

• Without trees, no leaf litter, which provides food and shelter for invertebrates: remove litter, remove invertebrates

• Without invertebrates, no food for carnivorous birds: remove other birds

Flow sheet, (Year 1 Woodlands PS)

See Connected Classrooms Activity: Nyitting Birds, which explores Noongar culture and the ways cultural values and practices contributed to the preservation of ecosystems.