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Human Impact on Habitats

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Human Impact on Habitats

Read the field-note story and study the data table. Then answer the questions using evidence and your own reasoning.

Field notes: Kōwhai Creek

Kōwhai Creek runs through a valley on Aotearoa New Zealand’s North Island. Its banks once had broad strips of native trees and shrubs. These plants provided shelter for birds, shaded the water and held soil in place with their roots. Insects and small fish lived among the stones and fallen leaves. Over time, some trees were cleared to make room for pasture and a road. After heavy rain, bare soil washed into the creek. The water became cloudier, and fine sediment covered spaces between the stones where aquatic insects lived. Run-off from nearby land could also carry nutrients into the creek, encouraging excess algae growth. Thick algae can block light and, when it decomposes, use oxygen in the water. A local group began planting native trees beside one section of the creek and fencing it to keep livestock out. Plant roots help bind the soil, while shade can keep the water cooler. The planting is not an instant fix: the trees need time to grow, and the group must monitor water quality and habitat over several years.

Monitoring the creek

The group measured water clarity at the same two sites during similar weather. A lower clarity reading means the water was cloudier. These results are observations, not proof that planting alone caused every change.

Site

Before planting

Two years later

Planted bank

Unplanted bank

Investigate, explain and plan

1.Which change described in the field notes most directly increased the amount of soil entering Kōwhai Creek?

Clearing trees and shrubs beside the creek
Planting native trees along the bank
Fencing livestock away from the water
Shading the creek with mature trees

2.Explain one way that sediment entering the creek could affect living things in the habitat.

3.True or false: Thick algae growth can reduce oxygen available in the water when the algae decomposes. Explain your choice.

4.Complete the sentence: Native plant roots help the soil, and tree shade can help keep creek water .

5.Match each action with the habitat effect it is most likely to have.

Clearing streamside trees
Fencing livestock away from the creek
Excess nutrients washing into water

Less trampling and direct disturbance at the bank
More chance of excessive algae growth
Less shade and weaker soil protection

6.Use the monitoring table. How much did clarity at the planted bank change, and how much did it change at the unplanted bank?

7.A student says, “The planting definitely caused all the improvement in clarity.” Is this conclusion fully supported by the table? Give one reason for your answer.

8.The planting group can take one more action: plant more native shrubs, add a rubbish bin beside a walking track, or put up a sign explaining why the creek bank is fenced. Choose one action and explain how it could help protect this habitat.

9.Name one useful measurement, besides water clarity, the group could collect over the next few years. Explain what it would help them find out.

10.Write a short message for a community noticeboard encouraging people to care for stream habitats. Include one practical action and a reason it matters.