The complex landscape and seascape of Aotearoa has shaped its unique biodiversity.

The active tectonic (folding and faulting of the Earth’s crust) history, along with glaciation and changes in sea level have made for a very diverse range of freshwater and land ecosystems.

Braided rivers, alpine screes and lakes formed from earthquake slips are all examples of how tectonic activity has shaped some of our most characteristic ecosystems.

The country’s marine environment includes the territorial sea and exclusive economic zone (EEZ). It covers a massive 4.2 million km2, 15 times larger than its land area. Our EEZ is one of the largest in the world.

Aotearoa is a global biodiversity hotspot. It's a part of the world where there are exceptional concentrations of species.

At least half of assessed species are endemic (not found elsewhere). However, the true proportion of endemic species is likely to be much higher. A large part of the remaining half is either unspecified in the NZ Threat Classification System (NZTCS) or unknown – so it's likely to contain a significant proportion of endemic species.

State and trends

There is currently a global biodiversity crisis. Aotearoa also faces a biodiversity crisis, though the degree of this crisis varies within elements of biodiversity across the land, freshwater and marine domains.

Of the 13,385 species identified under the NZTCS in 2019, 7% (1002) are classified as threatened with extinction, and a further 23% (3096) are ‘At Risk’.

Less than half of the land area of Aotearoa remains in indigenous vegetation cover. Wetland and duneland ecosystems have been reduced by at least 90% since human arrival.

Decline is still occurring – between 1996 and 2018 there was a net loss of 85,600 ha of indigenous forest, scrub, shrubland and grassland.

The decline in quality and mauri of fresh water since human arrival, along with freshwater habitat and species loss have impacts, not only for biodiversity but also for customary resources. Coastal water quality is degraded in some places and there has been a significant loss of some habitats such as mussel beds and seagrass meadows.

What we don’t know

Roughly one in three species assessed under the NZTCS in 2019 are considered to be ‘Data Deficient’ – meaning there is insufficient information to assign a conservation status. For some life forms, we know very little, e.g. only a small percentage of freshwater macroalgae, fungi, invertebrates and mosses have been assessed under the NZCTS.

There are notable differences in the completeness of knowledge available between species groups and domains. To put this into context, the Parliamentary Commissioner for the Environment (PCE) in Focusing Aotearoa New Zealand’s environmental reporting system (2019) found that environmental monitoring, particularly for biodiversity, contains major gaps and, where undertaken, is often fragmented.

Pressures on biodiversity

The major decline in many indigenous land-based species, and in some case their extinction, is largely the result of the:

• substantial reduction in the extent and quality of natural habitats
• impact of introduced predators and herbivores
• legacy of past impacts (including harvesting).

All freshwater habitats and species have suffered from:

• the effects of increased sedimentation
• eutrophication
• land development and water abstraction.

The pressures on marine biodiversity are varied and include:

• sedimentation in coastal areas
• impacts from harvesting
• the effects of pollution.

The impacts of climate change are already being felt. They will increasingly pose one of the biggest threats to indigenous biodiversity across the land, freshwater and marine domains.