Page 136 - Big Ideas Year 9 sciPAD 2025

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136 SCIPAD - BIG IDEAS - BOOK 1
LIFE AND THE TAIAO
Biodiversity
Biodiversity is a measure of the variety of living things (plants, animals, fungi and microorganisms) in
a particular ecosystem. Our biodiversity is unique to New Zealand and irreplaceable. It is essential
to our culture, identity and well-being.
Healthy ecosystems are vital for our everyday lives. Biodiversity provides the life supporting systems
that enable all organisms, including humans, to survive by recycling and protecting our water,
soil and nutrient resources. Biodiverse ecosystems also provide food, medicines and a range of
other resources. Healthy ecosystems are better able to withstand and recover from diseases and
extreme climate events.
New Zealand ecosystems have undergone extensive change since humans arrived approximately
800 years ago. As land was converted for human occupation, forests were logged or cleared to
make room for farms, estuaries were filled in, rivers were dammed to generate electricity and
streams buried or drained. Today, agricultural and horticultural land occupies nearly 42% of New
Zealand’s total land area. While these land uses are essential for economic reasons, the destruction
of these habitats has had a negative impact on New Zealand’s biodiversity.
Forests
Today, 24% of New Zealand is covered by native forest.
Outside National Parks, native forests are often found in
gullies and on steep slopes. Before people arrived, more
than 80% of New Zealand was covered in dense forest.
Grasslands
Before humans arrived, native scrub and tussock covered
approximately 10% of the land. Today 40% of New Zealand
is exotic grassland made up of only a few grass species.
Changes to native forest cover (% coverage)
Pre-human Pre-human
Present
Pre-human
Present
Changes to grassland cover (% coverage)
1. Define the term biodiversity. 

2. Outline why biodiversity is important. 


3. Use the information above to complete a bar graph that shows the percentage changes
in coverage from pre-human times to present day.
4. Suggest a reason for the change in each ecosystem.
(a) Native forest cover. 

(b) Grassland cover. 

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