At the time humans arrived in Aotearoa, some of our native flora and fauna had survived from when they existed in Gondwanaland.

Many of our species had also evolved considerably since Aotearoa split from Gondwanaland (about 80 million years ago).

The environmental factors that have shaped our biodiversity include:

• global weather patterns (including ice ages)
• sea level fluctuations
• massive geological events (eg volcano eruptions) and processes (eg mountain formation and large-scale erosion).

Around half of our assessed terrestrial flora and fauna are endemic – they are found nowhere else in the world. However this figure is likely to be much higher given that many species have yet to be assessed. 

State and trends

The arrival of humans in Aotearoa marked the beginning of significant impacts on indigenous biodiversity. These impacts increased substantially with European arrival in the early 1800s.

The state and trends of land-based biodiversity have been heavily affected by:

• vegetation clearance (particularly severe in coastal and lowland zones), and
• the impact of predators and herbivores.

Fifty-seven bird species that rely on land and/or freshwater habitats, have become extinct since human arrival.

Of the nearly 11,000 terrestrial species assessed in 2019:

• 811 species (7%) are ranked as 'Threatened'.
• 2416 species (22%) 'At Risk'.

One in three indigenous reptiles are threatened with extinction.

The recent trends suggest ongoing impacts. For example, between 2014 and 2018, 61 vascular plant species changed conservation threat status due to worsening declines in populations.

What we don't know

It's difficult to prioritise conservation effort without complete information for individual species. 

Data Deficient means there is insufficient information to assign a conservation status. This group includes a very large number of fungi, lichens and insects. Over one third of the country's indigenous land species assessed are considered to be 'Data Deficient'. That's 4,039 species, or 37%. 

Although we have recently improved our ability to manage some pressures (eg controlling predators at landscape scales), we still have large gaps in our knowledge about how and when to take action.

Land biodiversity pressures

The main reasons for clearing indigenous vegetation has been for:

• harvesting resources such as timber.
• converting land – mostly for agriculture, plantation forestry, and urbanisation.

These activities have reduced natural habitats in both quantity and quality.

Combined with the impact of predators and herbivores, there has been a major decline in many indigenous species – to the point of extinction in some cases.

Some established pressures are well known. However, we do not yet fully understand the complete range of pressures and their interactions on indigenous biodiversity.

There are urgent research challenges from emerging and increasing threats from:

• climate change.
• new diseases.
• biosecurity incursions.

Climate change is likely to exacerbate existing pressures. The range, distribution, and spread of many pests, for example, are all expected to increase. However, ecological systems are complex – it's difficult to predict exactly how climate change induced pressures might interact with other pressures, and what the cumulative impacts might be.