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Current state and trends

Native vegetation cover and legal protection

This section reports on the area of native vegetation cover in New Zealand and the legal protection it receives.

Each native land cover class is shown by area (measured by data from the Land Cover Databases 1 (LCDB 1) and 2 (LCDB 2)), and by land environment type (as classified by Land Environments of New Zealand, a land-based classification tool).

Table 12.4 shows the estimated change in area of New Zealand’s native land cover between 1997 and 2002, as well as the extent of legal protection each native cover class received.

Past and present land cover

In 2002, more than 13.3 million hectares of New Zealand’s land was covered by native land cover, as estimated by the Land Cover Database 2 (Table 12.4). This equates to 49.6 per cent of New Zealand’s total land area (26.9 million hectares). The area of native vegetation (excluding other native land cover, such as permanent snow and ice) equates to 43.7 per cent (11.7 million hectares) of New Zealand’s total land area.

Between 1997 and 2002, it is estimated that native land cover decreased by 16,500 hectares (0.12 per cent). This total decrease included an increase of 700 hectares of non-vegetative native cover, such as sand and gravel, and a decrease of 17,200 hectares of native vegetative cover. These changes either occurred through conversion of land to other uses, or as a result of natural processes.

The vegetation types that have experienced the greatest loss are broadleaved native hardwoods, mānuka and/or kānuka, tall tussock grassland, and native forest. Changes recorded by the Land Cover Database 2 show broadleaved native hardwood land cover was mainly converted into exotic forestry (83 per cent), or cleared for pasture (12.5 per cent). Similarly, mānuka and/or kānuka stands were converted into exotic forestry (52.5 per cent), or pasture (46 per cent).

The changes in native forest cover shown in Table 12.4 were largely due to harvesting (82.5 per cent) and some conversion to exotic forestry (11 per cent). All the tall tussock grassland cover that experienced land-use change was converted into exotic forestry.

Legal protection

Table 12.4 shows that in 2006, about 62.4 per cent (8.3 million hectares) of New Zealand’s total native land cover was legally protected. This represents 35 per cent of New Zealand’s total land area. Of our native vegetation (excluding other native land cover, such as permanent snow and ice), 63.7 per cent is legally protected.

Some native vegetation types receive comparatively high levels of protection. For example, in 2006, 79.6 per cent of the remaining native forests, 81.5 per cent of the remaining sub-alpine shrublands, and 80.7 per cent of the remaining alpine grass/herbfields were protected. Other vegetation types are represented to a lesser degree in legally protected areas.

Table 12.4: Estimated change in native vegetation and other native land-cover classes (1997 and 2002) using satellite imagery (LCDB 1 and LCDB 2) and the extent of legal protection for each land cover class

View estimated change in native vegetation and other native land-cover classes (1997 and 2002) using satellite imagery (LCDB 1 and LCDB 2) and the extent of legal protection for each land cover class (large table).

The Resource Management Act 1991 and biodiversity

The Resource Management Act 1991 has a key role in managing New Zealand’s terrestrial and freshwater biodiversity. Because almost all forms of resource use affect native biodiversity, biodiversity is recognised in the Act in many ways:

  • All plants and animals come within the definition of natural resources (section 5).

  • Section 6(c) refers to the protection of areas of significant native vegetation and significant habitats of native fauna.

  • Section 7(d) refers to the intrinsic value of ecosystems.

  • Section 30(1)(c)(iiia): Regional councils are responsible for controlling the use of land for the purpose of maintaining and enhancing ecosystems in water bodies and coastal waters.

  • Section 30(1)(ga): Regional councils are responsible for establishing, implementing, and reviewing objectives, policies, and methods for maintaining native biological diversity.

  • Section 31(b)(iii): Territorial authorities are responsible for controlling the effects of land use to maintain native biological diversity.

Amendments to the Act in 2003 clarified that regional councils and territorial authorities are responsible for managing native biodiversity. Local authorities must consider the consequences of all effects on native biodiversity, not simply the significance of a species or habitat.

Figure 12.2 maps New Zealand’s land environments into 20 classes, as identified in the Land Environments New Zealand classification. Table 12.5 shows the area and percentage of native land cover (both vegetative and non-vegetative) for each of the 20 land environments mapped in Figure 12.2. It also shows how much of these areas were legally protected in 2006. By combining the information shown in Table 12.4 and Table 12.5, we can see which areas have lost most native land cover, what the type of land cover was, and to what extent the remaining native land cover is legally protected.

Figure 12.2: New Zealand land environments as shown by the Land Environments of New Zealand classification

 See figure at its full size (including text description).

Table 12.5: Native land cover by land environment, and legally protected native land cover, 2006, within each land environment

View native land cover by land environment, and legally protected native land cover, 2006, within each land environment (large table).

Table 12.5 shows that it is generally lowland environments, some recent soils, and the eastern South Island plains that have lost substantial native land cover since human settlement. Where native land cover does remain within these land environments, there is mostly low to medium legal protection for conservation purposes (between 5 per cent and 40 per cent). This has implications for the threatened species that require unmodified lowland habitats to survive.

As an example, the western and southern North Island lowlands and eastern South Island plains have lost 95.8 per cent and 92 per cent of their respective original native land cover. Of these land environments, 21.4 per cent and 5.4 per cent, respectively, are legally protected.

In contrast, the central mountains and Southern Alps have lost less than 6.7 per cent and 1 per cent, respectively, of their original native land cover. Of this, 76.4 per cent and 94.2 per cent, respectively, of the remaining native land cover is under legal protection.

Wetlands

Wetland ecosystems, where land and freshwater meet, often support particularly high levels of biodiversity. They provide the water and nutrients that countless species of plants and animals depend on for survival (Ramsar Convention, 2007). However, increasing demand for accessible land has led to the conversion or modification (including drainage) of a large proportion of New Zealand’s wetland areas to provide pastoral land cover.

Figure 12.3 shows the estimated original and current extent of wetland areas. Just over 10 per cent of the original wetland environment remains across New Zealand (4.9 per cent of the original area in the North Island, and 16.6 per cent in the South Island). Of this amount, less than half is legally protected. Many of the remaining wetlands are situated on private land.

Wetlands cushion bog at Key Summit, Fiordland National Park.

Source: Courtesy of the Department of Conservation

Figure 12.3: Estimated pre-human and current (2007) extent of wetland areas

 See figure at its full size (including text description).

New Zealand has designated six wetlands as having global importance under the Ramsar Convention on Wetlands, 1971 (Table 12.6). Together, these wetlands cover a surface area of 39,068 hectares.

Table 12.6: Wetlands designated under the Ramsar Convention on Wetlands

Site name and location Date of designation Surface area in hectares Description

Farewell Spit, South Island

1976

11,388

Nature reserve; shorebird network site

A 30-kilometre long sand spit and inter-tidal area with a dune complex giving way to mudflats on the south. Particularly important as a staging area for shorebirds. Also supports several notable plant species.

Waituna Lagoon, South Island

1976

3,556

Scientific reserve

A coastal lagoon, peatlands, saltmarsh, gravel beach, ponds, and lakes. These habitats provide important areas for waders and various other waterbirds. Endemic butterfly species and two species of endangered fish occur. The site supports numerous native plant species, some typical of alpine regions.

Kopuatai Peat Dome, North Island

1989

10,201

Stewardship area; wildlife management reserve

The largest unaltered raised bog in New Zealand, surrounded by mineralised swampland and associated lagoons. Important area for threatened birds and plants, and notable invertebrates. A spawning site for threatened fish.

Whangamarino, North Island

1989

5,923

Stewardship area

The second largest peat bog and swamp complex on the North Island. The most important breeding area in New Zealand for matuku (Australasian bittern) and habitat for wintering birds and endangered species of plants and fish.

Firth of Thames, North Island

1990

7,800

Coastal reserve; shorebird network site

A large coastal reserve consisting of shallow marine water, mud and grass flats, mangrove swamp, saltmarsh, and swampland. Includes a globally rare land formation of graded shell beach ridges that support grazing. Important site for roosting, wintering, and staging wading birds.

Manawatū River mouth and estuary, North Island

2005

200

Estuarine system

An estuary retaining a high degree of naturalness and diversity, important as a feeding ground for migratory birds, including wrybill. The saltmarsh–ribbonwood community is the largest in the ecological district and contains its southernmost and biggest population of fernbirds (Bowdleria punctata). A high diversity of fish is supported, including some that are threatened. Archaeological signs of the semi-nomadic moa hunter culture dating from AD1400–1650 support Ramsar designation.

Source: Adapted from Ramsar Convention, 2007.

Legal protection of land

Land under legal protection for conservation purposes includes public conservation lands managed by the Department of Conservation, parks managed by regional authorities, and private land protected under covenant by the Queen Elizabeth II National Trust (QEII Trust) and Ngā Whenua Rāhui. Figures 12.4 and 12.5 show the location and extent of New Zealand’s land-based legally protected areas.

Figure 12.4: Legally protected areas – North Island, 2006

 See figure at its full size (including text description).

Figure 12.5: Legally protected areas – South Island, 2006

 See figure at its full size (including text description).

Tongariro was the first national park in New Zealand, established in 1887.

Source: Courtesy of the Department of Conservation.

Most legally protected land is part of the public conservation lands that cover large tracts of native forest and alpine areas. The Department of Conservation is responsible for preserving and protecting these areas, including managing threats from invasive pests and diseases.

By October 2007, 8.43 million hectares of land were legally protected for conservation purposes in New Zealand. This includes by public conservation lands managed by the Department of Conservation and councils, and private land protected under covenants by the QEII Trust and Ngā Whenua Rāhui.

What is Ngā Whenua Rāhui?

Ngā Whenua Rāhui is a contestable fund that was established in 1991 to promote the voluntary protection of native ecosystems on Māori-owned land. To date, about 146,800 hectares of native ecosystems have been protected through this fund.

Public conservation lands

Public conservation lands (Crown conservation land and council-protected land) have also increased. In 2004, 8.06 million hectares were set aside in New Zealand for public conservation land (Ministry for the Environment, 2004). By the end of October 2007, a total of 8.43 million hectares were legally protected, which is an increase of 4.56 per cent.

The increase in public conservation land has been partly achieved through the buy-back of Crown-owned land that was formerly leased or licensed to others. The Crown Pastoral Land Act 1998 authorised the review of 304 state-owned properties totalling 2.37 million hectares in the South Island high country, which had been leased to farmers for livestock grazing since the 1940s. The review’s objectives are to promote ecologically sustainable land management, protect land that has significant inherent value, secure public access to and enjoyment of the land, and dispose of any surplus land.

By September 2006, 226,000 hectares had been transferred to full government ownership to create a network of high-country parks and reserves.

Private conservation of land

While most of the effort to protect New Zealand’s native vegetation occurs on legally protected land, efforts to protect native vegetation on private and council-owned land are increasing.

In 2004, a total of 146,280 hectares were registered as formally protected private land (Ministry for the Environment, 2004). By June 2006, registered QEII National Trust and Ngā Whenua Rāhui covenants formally protected a total of 221,473 hectares. The area on private land that is legally protected through these two mechanisms has increased by 51.4 per cent over this two-year period.

As an example, the number of covenants processed through the QEII Trust has continuously increased since 1977. By June 2007, 82,933 hectares were legally protected through more than 2,600 QEII Trust covenants. Figure 12.6 shows the location of QEII Trust covenants, as well as the number of registered QEII Trust covenants and the total land area protected by June 2006.

Private conservation initiatives

What is the Landcare Trust?

The Landcare Trust was established in 1996, with the vision of promoting sustainable land management. There are currently more than 250 landcare groups operating around New Zealand. Their level of activity and pace depends on the community they are based in and the specific issues they are trying to address.

Landcare groups are particularly numerous and active in some regions. Major initiatives are prominent where regional councils have set up active programmes for biodiversity protection and offer incentives or assistance to landholders (Davis, 2002).

Karori Wildlife Sanctuary

The Karori Wildlife Sanctuary, located 2 kilometres from Wellington city and run by a charitable community trust, has been developed as a major educational, research, and recreational site for the benefit of all New Zealanders.

The sanctuary is a 252-hectare haven for endangered native birds and other wildlife. A predator-proof fence, specifically designed to exclude 14 species of non-native mammals ranging from possums to mice, encircles the 8.6-kilometre perimeter.

Many threatened species of native wildlife are expected to be reintroduced to the sanctuary as appropriate habitats recover. The little spotted kiwi, stitchbird (hihi), weka, saddleback (tīeke), kākā, bellbird (korimako), whitehead (pōpokatea), and tuatara have already been released there.

Figure 12.6: Location of Queen Elizabeth II National Trust covenants and registered covenants, and area protected, June 2006

 See figure at its full size (including text description).

More about the Queen Elizabeth the Second National Trust

The Queen Elizabeth the Second National Trust (QEII Trust) is a statutory organisation, independent from government, which was established in 1977 under the Queen Elizabeth the Second National Trust Act 1977.

The QEII Trust was established at the request of New Zealand farmers to protect open space on private land for the benefit and enjoyment of the present and future generations of New Zealanders.

A covenant is generally requested by the landowner and registered against the title of the land in perpetuity. The values of each covenant are identified in the covenant document. Each registered covenant is monitored every two years to ensure the land is managed in accordance with the covenant document. More than 95 per cent of covenant owners meet or exceed covenanting requirements with a resulting increase in biodiversity and sustainability of land and resources.

Over the past 10 years, landowners have increasingly recognised a QEII covenant as a mechanism to protect areas of land they value. Councils see QEII covenants as a cost effective method to manage and improve biodiversity in their regions.

The QEII Trust generally contributes to the cost of fencing, surveying, and registration on the title, often with the help of local or regional councils or conservation groups.

As a result of increases in the area protected by covenant, many of New Zealand’s ecosystem types that have become uncommon due to human activity are now represented in the QEII Trust covenanted areas. The number of covenants that include these rare habitats and ecosystems, such as wetlands and lowland forests, has increased. Table 12.7 shows the increase in QE11 covenants for lowland forest and wetland systems since the late 1990s.

Table 12.7: Registered covenants by the Queen Elizabeth II National Trust, and the ecosystem types within them

View registered covenants by the Queen Elizabeth II National Trust, and the ecosystem types within them (large table).

Some of New Zealand’s most endangered species find refuge in QEII Trust covenanted areas. For example, Table 12.8 shows that 51 QEII Trust covenants are home to at least one of the native indicator species shown in Table 12.3.

Table 12.8: Occurrence of species covered in this report that are found in Queen Elizabeth II National Trust covenants, 2007

Species Number of covenants where species is present Total area (hectares) of covenants where species is present

Kiwi (North Island brown)

38

2,329

Kākā

10

339

Wrybill

1

1

Mōhua

1

8

Dactylanthus

1

39

Total

51

2,716

Data source: Queen Elizabeth II National Trust.

Distribution of selected native species

The following maps provide information on the distribution of the seven selected native species used as indicators of biodiversity levels. All seven species show a marked decrease in their range since human settlement, due to loss of habitats and the impacts of introduced pests.

Figure 12.7: Change in distribution of the lesser short-tailed bat

 See figure at its full size (including text description).

The lesser short-tailed bat currently occupies less than 5 per cent of the range it was estimated to have before human settlement. Its current distribution is about 75 per cent of its range in the 1970s.

The northern lesser short-tailed bat is found at two sites in Northland and one on Little Barrier Island. The central lesser short-tailed bat is found in Northland, the central North Island, and Taranaki. The southern lesser short-tailed bat is found in the Tararua Ranges, on Codfish Island, in northwest Nelson, and in Fiordland.

Figure 12.8: Change in distribution of the kiwi

 See figure at its full size (including text description).

The brown kiwi is still widespread in the central and northern North Island. Rowi are found only at South Ōkarito on the West Coast, but distinct populations of tokoeka (formerly believed to be brown kiwi) are present at Haast, Fiordland, and on Stewart Island. Great spotted kiwi can be found in the northwestern South Island, while little spotted kiwi are restricted to five offshore islands and the Karori Wildlife Sanctuary in Wellington.

Kiwi now occupy about 17 per cent of their estimated original range, as a result of habitat loss and predation. Since the 1970s, their range has decreased by about 20 per cent.

Figure 12.9: Change in distribution of the kākā

 See figure at its full size (including text description).

In the 19th century, kākā were abundant throughout forests in the North and South Islands, but by 1930 they had become more localised. North Island kākā are now almost absent from many large forested areas with high levels of predators. They are still common in some central North Island forests, but even within these strongholds kākā are thought to be declining. They are still also common on some larger offshore islands.

The South Island subspecies is still widespread, although low in number, and has become progressively more common on the West Coast of the South Island to Fiordland, and on Stewart Island.

Kākā currently occupy less than 20 per cent of their original range, and recent evidence suggests that most populations without predator control are declining and remaining populations may consist of predominately males (Moorehouse et al, 2003). Since the 1970s, the kākā’s range has contracted a further 6 per cent.

Figure 12.10: Change in distribution of the kōkako

 See figure at its full size (including text description).

Before human settlement, kōkako were widespread and common. Until 1995, there was a marked decline in kōkako numbers, but recent management of the remaining populations has reversed that trend and the national population is increasing.

Kōkako are currently present in 2 per cent of their estimated natural range. Since the 1970s, their range has been reduced by a further 90 per cent. There have been successful transfers to offshore islands.

Figure 12.11: Change in distribution of the mōhua

 See figure at its full size (including text description).

Mōhua are found only in South Island forests. Their distribution has become very fragmented and the species is now confined to beech forest.

They are present in 5 per cent of their estimated natural range. Since the 1970s, their range has contracted by almost 70 per cent, and in areas where there is no predator control, mōhua numbers are continuing to decline.

Figure 12.12: Change in distribution of the wrybill

 See figure at its full size (including text description).

Wrybills currently breed only in braided rivers east of the main divide in Canterbury and northern Ōtago. They previously bred in a number of Marlborough rivers, but their range has contracted southwards in the past 100 years.

They now occupy about 60 per cent of their estimated original range.

Figure 12.13: Change in distribution of dactylanthus

 See figure at its full size (including text description).

Dactylanthus is found from Northland to the Wairarapa, with the largest populations in East Cape and on the Central Plateau. There is also a small population on Little Barrier Island. However, the distribution and number of plants has declined recently, and there are likely to be only a few thousand remaining.

Dactylanthus is currently distributed in only 4 per cent of its former range, with its range decreasing 32 per cent since the 1970s.

More about New Zealand’s native birds

Some of our more common native birds have shown an increase in distribution in recent years, particularly in certain urban areas (Robertson et al, 2007). It is thought that this increase is due to intensive local pest control efforts and plantings of native plants in gardens to attract these species.

For example, tūi, bellbird/korimako and New Zealand pigeon/kererū are important pollinators and seed dispersers for many of New Zealand’s trees and shrubs. These are among the 27 native species that have increased in distribution since 1985, as shown in Table 12.9 (0r 28 per cent of the 96 observed species).

Table 12.9 also shows that, despite some gains with our more common birds, the same percentage (28 per cent) of New Zealand’s birds have also decreased in distribution since 1985. However, 93 per cent of these are endemic species (those that do not naturally occur elsewhere in the world).

Table 12.9: Summary of observed changes in distribution of birds, 1985–2004

Trend

Endemic species

Native species

Total

Increase

15

12

27

No change

26

16

42

Decrease

25

2

27

Total

66

30

96

Source: Adapted from Robertson et al, 2007.

Tūi (Prosthemadera novaeseelandiae).

Photo of a Tūi.

Source: Courtesy of the Department of Conservation.

Bellbird/korimako (Anthornis melanura).

Phot of a Bellbird.

Source: Courtesy of the Department of Conservation.

New Zealand pigeon/kererū (Hemiphaga novaeseelandiae).

Photo of a New Zealand pigeon.

Source: Courtesy of the Department of Conservation.

Pest management in New Zealand

Following the initial large-scale deforestation of New Zealand before and during the 19th century, the habitat for many threatened vertebrate species in New Zealand has largely come under legal protection.

However, introduced predators and competitors such as stoats, rats, and possums continue to reduce the populations of some of our most at-risk bird species. They do so by feeding on eggs, chicks, and adults, and by competing for food and nesting sites.

Protecting native species from predation and competition by introduced animals and weeds is therefore critical if we are to sustain the remaining populations and avoid further biodiversity loss. Protection largely relies on ongoing control of animal pests and weeds.

Pests are unwanted organisms that adversely affect ecosystems and directly compete with native or commercial species. Established introduced pest species are the single largest threat to New Zealand’s remaining biodiversity (Department of Conservation and Ministry for the Environment, 2000), and substantial efforts are directed towards controlling and eradicating them.

New Zealand’s biosecurity system is a multi-agency programme that aims to exclude unwanted organisms at the border, and to control incursions and growth of pest populations within the country. It aims to exclude and control the invasive species that threaten our natural species and ecosystems, and those species that underpin our primary production sector.

Biosecurity efforts include pest management for conservation and animal health purposes. Because bovine tuberculosis (Tb) – a disease affecting livestock and humans – is transmitted by possums, the control of possum numbers has benefits for both conservation and New Zealand’s farming industry.

However, reducing the risk of Tb-transmission from possums to cattle may not be enough on its own to protect our native biodiversity. In addition, when low Tb levels have been achieved, and possum management ceases, biodiversity gains may be reversed in some areas.

Figure 12.14 shows the areas of the country where possum control or surveillance is carried out by the Animal Health Board (the organisation responsible for managing and implementing the National Pest Management Strategy for bovine Tb) and the Department of Conservation. Other pest groups such as rodents, mustelids (primarily stoats), cats, hedgehogs, pest grazers (including rabbits), and weeds are also managed in some of these areas.

The Australian brushtail possum has become one of the greatest threats to New Zealand's biodiversity. It was introduced in 1837 to establish a fur trade.

Photo of an Australian brushtail possum.

Source: Courtesy of the Department of Conservation.

Figure 12.14: Areas where sustained management of brushtail possums is carried out by the Department of Conservation and Animal Health Board, 2006

 See figure at its full size (including text description).

In the past decade, animal pest and weed control efforts have significantly increased in their extent and intensity. Table 12.10 shows the area managed for pest groups within mainland public conservation lands. Figure 12.15 shows the trend in the land area receiving sustained control for possums, deer, goats, thar, and weeds.

As an example, since 2000, the area of Department of Conservation land under sustained management for possums has increased by 60 per cent, from 669,000 hectares to 1,069,000 hectares in 2006. Within sustained pest control areas, targeted pest treatment also increased from 40,000 hectares in 1991 to 302,000 hectares in 2006.

The area controlled for possums by the Animal Health Board has also increased by 40 per cent, from 6,153,200 hectares in 2001 to 8,870,000 hectares in 2006.

This results in a total of 9,939,000 hectares under sustained possum management in 2006, which constitutes about 37 per cent of New Zealand’s total land area. This figure excludes all council and private management activities.

Control methods (for example, trapping, culling, and poisoning), the ease of access to affected ecosystems, the threat to biodiversity, the range of pests present, the severity of a pest’s impact on native species, and the available resources largely determine the pest control effort and which pest group is targeted.

Table 12.10: Pest management on public conservation lands by pest group and area under management (2005/2006)

Pest group Area managed (hectares)

Rodents

312,676

Mustelids/cats

417,618

Pest herbivores1

4,859,498

Weeds

2,635,405

Possums

1,078,053

Notes:
(1) Pest herbivores include deer, goats, pigs, thar, chamois, wallabies, rabbits, sheep, and cattle.

(2) Areas do not total, as in some cases more than one pest is managed in the same area.

Data source: Department of Conservation.

Figure 12.15: Land area under sustained management of pest species by the Department of Conservation, 2000–2006

 See figure at its full size (including text description).

Freshwater pests

Freshwater resources face pressures similar to land-based areas. Introduced fish and aquatic weeds and algae compete with and displace our native aquatic plants and animals. Pest aquatic plants have invaded 61 per cent of lakes in New Zealand (National Institute of Water and Atmospheric Research, pers comm).

The monitoring of five major aquatic weeds (Ceratophyllum demersum, Egeria densa, Lagarosiphon major, Elodea canadensis, and Hydrilla verticillata) shows a jump in recorded incidences of these pest species, from 95 sites in 1970 to 778 sites in 2004 (Figure 12.16).

Figure 12.16: Recorded distribution of major invasive submerged weeds (Ceratophyllum demersum, Egeria densa, Lagarosiphon major, Elodea canadensis, and Hydrilla verticillata) in freshwater systems, 1970 and 2004

What is didymo (‘rocksnot’)?

Didymosphenia geminata – known as didymo, or ‘rocksnot’ because of its slimy appearance – is an introduced freshwater alga.

While it does not pose a risk to human health, didymo can form large algal mats on the bottom of rivers and streams and, occasionally, on lake edges. As these mats smother rocks, they can reduce the availability of suitable habitats for freshwater fish, invertebrates, and plant species. The presence of didymo may also affect riverbed bird species, such as the wrybill, by reducing their prey numbers and access to waterways.

As a result, didymo has been classed as an unwanted organism (pest species) under the Biosecurity Act 1993.

Didymo occurs naturally in northern parts of the northern hemisphere. It was first identified in New Zealand in October 2004 in the Lower Waiau River in Southland and was the first recorded occurrence in the southern hemisphere.

Since then, it has spread to a number of other river catchments in the South Island. By June 2007, it was found in 55 South Island rivers (Biosecurity New Zealand, 2007), but North Island rivers remain free of the pest. However, many rivers in the North Island, particularly around the central Volcanic Plateau, have environments that are suitable for didymo to take hold.

Didymo is easily spread between waterways on boating, fishing, or other equipment that has not been thoroughly cleaned. It is estimated that up to 50 per cent of all waterways in New Zealand are at risk of didymo incursion (Kilroy et al, 2005).

Intensive biodiversity conservation efforts

Conservation on offshore islands

Pest eradication, as opposed to pest control, can be accomplished in isolated areas that have low risk of reinvasions. Offshore islands that have remained free or have been cleared of introduced predators have been invaluable for the survival of many of New Zealand’s most threatened species . In these environments, species may establish new populations in safe havens, free of introduced pests.

Conservation on the mainland

Habitat limitations mean New Zealand’s threatened native biodiversity cannot be sustained on offshore islands alone. On the mainland, a number of areas have undergone intensive pest control to hold pest numbers at low thresholds (Table 12.11). These include the Department of Conservation’s ‘mainland island’ projects (1995–1996), kiwi sanctuaries, Operation Ark (2003), and other projects initiated by community groups.

Table 12.11 shows that over 500,000 hectares of land are under intensive pest management by the Department of Conservation on offshore islands and the mainland.

Table 12.11: Area under intensive pest management by the Department of Conservation, 2006

Type of area Area (hectares)

Offshore islands

153,895

Operation Ark

208,579

‘Mainland islands’

64,182

Kiwi sanctuaries

59,000

Kōkako mainland sites

15,000

Total

500,656

Data source: Department of Conservation.

Government action on biodiversity

Mainland islands

Six 'mainland island' projects were initiated by the Department of Conservation in 1995 and 1996. These are not actual islands surrounded by sea, but areas that are intensively managed on mainland New Zealand to restore native ecosystems. In total, more than 64,000 hectares and a range of native species are intensively managed at these six sites.

In less than five years, significant reductions of targeted pests were achieved, resulting in the recovery of many native species, as well as building organisational capability, and providing opportunities for learning.

The ‘mainland island’ projects have produced some measurable conservation outcomes over the last decade. These include:

  • confirming that pest management enhances the recovery of targeted native species and revitalises ecological processes

  • demonstrating that biodiversity declines can be halted on the mainland

  • providing opportunities for the public to visit and participate in conservation management and to interact with rare species

  • improving conservation practices through:

    • increasing the effectiveness of predator management techniques and practices
    • improving bird translocation techniques
    • providing flagship sites that have paved the way for other similar projects.

Kiwi sanctuaries

Much of the work on biodiversity protection is funded by central government in support of the New Zealand Biodiversity Strategy. This includes the Kiwi Sanctuaries programme, aimed at halting the decline of kiwi populations and decrease in their range in most mainland areas.

There are three kiwi sanctuaries in the North Island and two in the South Island. Each of these sanctuaries protects a different kiwi species or special population. Intensively managed sanctuaries and kiwi zones now play a key role in turning around the decline in kiwi numbers on New Zealand’s mainland.

Operation Ark

The Department of Conservation’s Operation Ark projects were established after the populations of orange-fronted kākāriki and mōhua more than halved, following rodent and stoat plagues in South Island beech forests in 2000 and 2001.

The areas selected span more than 200,000 hectares throughout the South Island. They include four of the most important sites for mōhua and blue duck/whio populations, sites containing the last two populations of the lesser short-tailed bat, and the key sites for orange-fronted kākāriki.

The operation involves progressively expanding possum control and setting tens of thousands of stoat and rat traps in permanent trap lines throughout the 11 ‘Ark’ areas.

Local action on biodiversity

Regional councils and territorial authorities use a range of tools to support native biodiversity. These include:

  • conservation covenants and help with establishing QEII National Trust covenants

  • subdivision controls

  • incorporation of biodiversity protection in management plans and agreements

  • rates relief for land under private conservation covenant

  • education and advice for land owners

  • support for volunteer community groups, landcare groups, and conservation trusts, and waiving consent fees.

Since 1997, the extent of council effort and expenditure on biodiversity protection has increased. Regional councils now invest more than $4.26 million per year in contestable biodiversity funds. Many of these funds support on-the-ground activities such as covenants, landcare groups, education, and land owner advice.

One example is the Biodiversity Condition and Advice Fund, which aims to enhance the management of native biodiversity outside public conservation lands. By May 2006, these funds had directly benefited 4,800 private land owners, either through advice received or work undertaken on their property to protect biodiversity.

Some other examples of regional council approaches to protect local biodiversity are:

  • provisions for native biodiversity in the regional policy statements for Taranaki, Hawke’s Bay, Wellington, Canterbury, and Ōtago

  • extensive biodiversity programmes in Auckland Regional Council’s regional parks, such as:

    • protection programmes (including predator control) for threatened shorebirds in many coastal regional parks (such as Whakanewha, Wenderholm, and Mahurangi), many of them in conjunction with community groups
    • the Ark in the Park initiative, a joint programme with the Royal Forest and Bird Protection Society to restore birds to the Waitākere Ranges
    • a joint programme with the Department of Conservation to conserve kōkako in the Hūnua Ranges Regional Park
    • a sanctuary (‘mainland island’) established at Tawharanui in 2004
  • coastal care groups operated by several regional councils (such as Waikato and Bay of Plenty).

Local plant and animal pest control also plays an important role in maintaining New Zealand’s native biodiversity. All regional councils help control the animals and weeds that have been identified as pests in their regions, although land owners have the primary responsibility for pest management on their properties.

Much of the pest control work undertaken for the benefit of agriculture, such as the control of bovine Tb, also has direct benefits for biodiversity. Most of these programmes are aligned or integrated with biodiversity pest control carried out by the Department of Conservation, the QEII National Trust, and community groups.