Category Archives: Podocarp forest

Ecological restoration in urban environments in New Zealand – UPDATE of EMR feature

Bruce Clarkson, Catherine Kirby and Kiri Wallace

[Update of EMR feature  – Clarkson, B.D. & Kirby, C.L. (2016) Ecological restoration in urban environments in New Zealand. Ecological Management & Restoration, 17:3, 180-190.  https://onlinelibrary.wiley.com/doi/10.1111/emr.12229]

Key words: urban ecology; restoration; indigenous biodiversity; New Zealand

Figure 1. Kauri dieback disease is affecting individual trees (left). [Photo Nick Waipara]

Introduction. Our 2016 EMR feature reviewed the state of research and practice of ecological restoration in urban environments in New Zealand. We concluded that urban restoration can influence and support regional and national biodiversity goals. We also observed that research effort was light, lacking interdisciplinary breadth and may not be sufficiently connected to restoration practice to ensure long-term success of many projects.

While it is only three years since that review was published, urban ecological restoration continues to grow and evolve, and the policy setting and political context have changed significantly. New threats and opportunities have emerged. The spread of a dieback disease and the more recent arrival of myrtle rust, rapid uptake of Predator Free 2050, emergence of the One Billion Trees programme, a surge in housing and subdivision development, and a potentially more supportive policy framework are all major factors.

Threats and opportunities. Kauri dieback disease is severely affecting urban kauri forests and individual Kauri (Agathis australis) trees in Auckland and other northern North Island urban centres (Fig. 1). Large forest areas adjoining Auckland, including most notably the Waitākere Range and large parts of the Hunua Range, are now closed to the public, preventing access to popular recreational areas. The dieback is caused by a fungus-like pathogen Phytophtora agathicida that is spread through soil movement. The disease may have arrived from overseas although this is uncertain. There is no known cure but research efforts are underway to find a large-scale treatment option.

Myrtle rust (Austropuccinia psidii) was first found on mainland New Zealand in May of 2017, probably arriving by wind from Australia. Myrtle rust threatens many iconic New Zealand plant species in the family Myrtaceae including Pōhutukawa (Metrosideros excelsa), Mānuka (Leptospermum scoparium), Rātā (Metrosideros robusta), Kānuka (Kunzea spp.), Waiwaka (Syzygium maire) or Swamp maire, and Ramarama (Lophomyrtus bullata). These species are all used to a greater or lesser extent in restoration planting or as specimen trees or shrubs in urban centres, depending on amenity or ecological context. Mānuka is widely used as a pioneer or nurse crop for native forest restoration and is critical to the economically important mānuka honey industry. Waiwaka is a feature of many swamp forest gully restoration projects in Hamilton and this would be a significant setback if they were badly affected. The impact of myrtle rust is still not clear but experience from Australia suggests it may take several years before it reaches population levels sufficient to cause significant damage.

Figure 2. With rapid housing developments in New Zealand, it is important that urban restoration projects are well-planned and efficiently carried out to provide residents with greenspaces to benefit their cultural, health and wellbeing practices. [Photo Catherine Kirby]

In response to a range of housing issues characterised by many as a New Zealand housing crisis, the previous and current government has embarked on several major initiatives to increase the housing stock. A $1B Housing Infrastructure Fund (HIF) was established in October 2016 with provision for interest free loans to local government to enable opening up of new large areas of housing. Many urban centres including Auckland, Tauranga, Hamilton and Queenstown made early applications to the fund. Hamilton City Council was successful in obtaining $290.4 M support for a new greenfield subdivision in Peacocke on the southern edge of the city. This subdivision is intended to enable development of some 3700 houses over the next 10 years and 8100 in 30 years. Approximately 720 ha of peri-urban pastoral agricultural land would eventually be developed (See summary). Coupled with this, and already in progress, is the construction of the Southern Links state highway and local arterial road network. The first proposed subdivision Amberfield covers 105 ha and consent hearings are currently in progress. The environmental impacts of the proposal and how they might be mitigated are being contested. In brief, survival of a small population of the critically endangered Long-tailed Bat (Chalinolobos turberculatus) is the main environmental focus but other aspects including the extent of greenspace and ecological restoration required for ecological compensation are being considered (Figs. 2, 3). With strong political pressure to solve the housing crisis in Hamilton and in other urban centres, making adequate provision for greenspace, especially urban forest, and preventing environmental degradation and indigenous biodiversity decline will be a major challenge.

Figure 3. Aerial photo of Waiwhakareke Natural Heritage Park (65 ha), an award-winning and ongoing ecological restoration project situated on the edge of urban Hamilton. [Photo Dave Norris]

The Predator Free 2050 (PF2050) programme which gained government (National) approval in 2015, aims to eradicate Stoat (Mustela erminea), Ship Rat (Rattus rattus), Norway Rat (Rattus norvegicus) and Possum (Trichosurus vulpecula) from the whole of New Zealand by 2050 (Department of Conservation 2018). PF2050 is now gaining significant traction in urban environments (Figs. 4, 5) with many urban centres having good numbers of community-led projects underway (See PFNZ National Trust map). Crofton Downs in Wellington was New Zealand’s first predator-free community project. Led by Kelvin Hastie this project has effectively reduced predator numbers to the point that some sensitive native birds e.g. Kākā (Nestor meridionalis), have begun to nest in this suburb after an absence of more than 100 years (See RNZ report). Also in Wellington, the Miramar Peninsula (Te Motu Kairangi) has become a focus, because of its advantageous geography, with a goal to make the area predator free by 2019. Possums had already been exterminated in 2006 (www.temotukairangi.co.nz).

Figure 4. John Innes (Wildlife Ecologist, Manaaki Whenua Landcare Research) demonstrating trapping success. Removing pest mammals reduces predation, and also frees up the habitat and resources for our native fauna and flora to flourish. [Photo Neil Fitzgerald]

The One Billion Trees (1BT) programme was initiated by the new coalition government (Labour, NZ First, Greens) in 2017 with $238M released in 2018 for planting of both exotic and native trees across mixed land use types. It is not clear yet whether urban forest projects have received funding support but the guidelines suggest there is no reason why restoration of native forest in urban settings would not be eligible. While the emphasis is on exotic tree plantations, native species and long-term forest protection are increasingly being considered as viable options by the newly established government forestry agency Te Uru Rākau.

The policy setting for ecological restoration in urban environments is potentially becoming more favourable with the draft National Policy Statement on Indigenous Biodiversity (NPSIB) currently in review and the New Zealand Biodiversity Strategy under revision (See terms of reference). The draft NPSIB emphasises restoration of indigenous habitat in biodiversity depleted environments. Specifically, Policy 19: Restoring indigenous biodiversity depleted environments, recommends a target for indigenous land cover, which in urban areas and peri-urban areas must be at least 10 per cent. The revision of the New Zealand Biodiversity Strategy seems likely to give more emphasis to landscape scale restoration including urban environments.

Figure 5. New Zealand native lizards are extremely vulnerable to mammalian predation (e.g. mice, hedgehogs, ferrets, cats) as well as habitat destruction (e.g. new urban developments). [Photo Tony Wills]

Research update. Using the same targeted Google Scholar search method as reported in the EMR feature we have found 18 new peer reviewed papers published between 2015 and July 2019 (see updated bibliography) that are strongly focused on restoration in New Zealand urban environments. The single paper noted for 2015 was missed in our previous search. Again, we have not included books, book chapters or grey literature. This compares very favourably with the total 27 papers listed in our 2016 review of which more than half dated from 2009. An increasing publication rate confirms increasing interest and research efforts in aspects of urban ecological restoration. While most of the publications remain in the ecological science realm there are now some informed by other disciplines including engineering, psychology, landscape architecture and health sciences.

Most notably since our 2016 review, a new government-funded (Ministry of Business, Innovation and Employment) research programme, People, Cities and Nature, began in November of 2016. This four-year $823 k per annum research programme ends in October of 2020 unless a funding rebid to be submitted in March 2020 is successful. The programme undertakes multidisciplinary research in nine NZ cities via six inter-related projects: restoration plantings; urban lizards; mammalian predators; Māori restoration values; green-space benefits and cross-sector alliances. While the emphasis was on the ecological science of urban restoration at the outset, the programme has become increasingly involved in understanding the multiple benefits of urban ecological projects including social cohesion and health and recreation benefits. The need to connect restoration research and practice has been met by undertaking multi-agency and community workshops involving researchers and practitioners in five cities to date with a further four scheduled before the programme ends.

Acknowledgements. The People Cities and Nature research programme is funded by the Ministry of Business Innovation and Employment under grant number UOW1601.

Information. Bruce D. Clarkson, Environmental Research Institute, University of Waikato, Hamilton, New Zealand bruce.clarkson@waikato.ac.nz; Catherine L. Kirby, Environmental Research Institute, University of Waikato, Hamilton, New Zealand catherine.kirby@waikato.ac.nz; and Kiri J. Wallace, Environmental Research Institute, University of Waikato, Hamilton, New Zealand kiri.wallace@waikato.ac.nz.

The Tiromoana Bush restoration project, Canterbury, New Zealand

Key words: Lowland temperate forest, animal pest control, weed control, restoration plantings, public access, cultural values, farmland restoration

Introduction. Commencing in 2004, the 407 ha Tiromoana Bush restoration project arose as part of the mitigation for the establishment of the Canterbury Regional Landfill at Kate Valley, New Zealand. The site lies one hour’s drive north of Christchurch City in North Canterbury coastal hill country (Motunau Ecological District, 43° 06’ S, 172° 51’ E, 0 – 360 m a.s.l.) and is located on a former sheep and beef farm.

Soils are derived from tertiary limestones and mudstones and the site experiences an annual rainfall of 920mm, largely falling in winter. The current vegetation is a mix of Kānuka (Kunzea robusta) and mixed-species shrubland and low forest, restoration plantings, wetlands, Gorse (Ulex europaeus) and European Broom (Cytisus scoparius) shrubland and abandoned pasture. Historically the area would have been forest, which was likely cleared 500-700 years ago as a result of early Māori settlement fires. A total of 177 native vascular plant and 22 native bird species have been recorded, including four nationally threatened species and several regionally rare species.

Before and after photo pair (2005-2018). showing extensive infilling of native woody vegetation on hill slopes opposite, restoration plantings in the central valley, and successional change from small-leaved shrubs to canopy forming trees in the left foreground. (Photos David Norton.)

 

Project aims. The long-term vision for this project sees Tiromoana Bush, in 300 years, restored to a: “Predominantly forest ecosystem (including coastal broadleaved, mixed podocarp-broadleaved and black beech forests) where dynamic natural processes occur with minimal human intervention, where the plants and animals typical of the Motunau Ecological District persist without threat of extinction, and where people visit for recreation and to appreciate the restored natural environment.”

Thirty-five year outcomes have been identified that, if achieved, will indicate that restoration is proceeding towards the vision – these are:

  1. Vigorous regeneration is occurring within the existing areas of shrubland and forest sufficient to ensure that natural successional processes are leading towards the development of mature lowland forest.
  2. The existing Korimako (Bellbird Anthornis melanura) population has expanded and Kereru (Native Pigeon Hemiphaga novaeseelandiae) are now residing within the area, and the species richness and abundance of native water birds have been enhanced.
  3. The area of Black Beech (Fuscospora solandri) forest has increased with at least one additional Black Beech population established.
  4. Restoration plantings and natural regeneration have enhanced connectivity between existing forest patches.
  5. Restoration plantings have re-established locally rare vegetation types.
  6. The area is being actively used for recreational, educational and scientific purposes.

Day-to-day management is guided by a five-year management plan and annual work plans. The management plan provides an overview of the approach that is being taken to restoration, while annual work plans provide detail on the specific management actions that will be undertaken to implement the management plan.

Forest restoration plantings connecting two areas of regenerating Kānuka forest. Photo David Norton.

 

Restoration approach and outcomes to date. The main management actions taken and outcomes achieved have included:

  • An Open Space Covenant was gazetted on the title of the property in July 2006 through the QEII National Trust, providing in-perpetuity protection of the site irrespective of future ownership.
  • Browsing by cattle and sheep was excluded at the outset of the project through upgrading existing fences and construction of new fences. A 16 km deer fence has been built which together with intensive animal control work by ground-based hunters has eradicated Red Deer (Cervus elaphus) and helped reduce damage caused by feral pigs (Sus scrofa domesticus).
  • Strategic restoration plantings have been undertaken annually to increase the area of native woody and wetland vegetation, as well as providing food and nesting resources for native birds. A key focus of these has been on enhancing linkages between existing areas of regenerating forest and re-establishing rare ecosystem types (e.g. wetland and coastal forest).
  • Annual weed control is undertaken focusing on species that are likely to alter successional development (e.g. wilding conifers, mainly Pinus radiata, and willows Salix cinerea and fragilis) or that have the potential to smother native regeneration (e.g. Old Man’s Beard Clematis vitalba). Gorse and European Broom are not controlled as they act as a nurse for native forest regeneration and the cost and collateral damage associated with their control will outweigh biodiversity benefits.
  • Establishment of a public walking track was undertaken early in the project and in 2017/2018 this was enhanced and extended, with new interpretation included. Public access has been seen as a core component of the project from the outset so the public can enjoy the restoration project and access a section of the coastline that is otherwise relatively inaccessible.
  • Part of the walkway upgrade included working closely with the local Māori tribe, Ngāi Tūāhuriri, who have mana whenua (customary ownership) over the area. They were commissioned to produce a pou whenua (land marker) at the walkway’s coastal lookout. The carvings on the pou reflect cultural values and relate to the importance of the area to Ngāi Tūāhuriri and especially values associated with mahinga kai (the resources that come from the area).
  • Regular monitoring has included birds, vegetation and landscape, with additional one-off assessments of invertebrates and animal pests. Tiromoana Bush has been used as the basis for several undergraduate and postgraduate student research projects from the two local universities.
Vigorous regeneration of Mahoe under the Kānuka canopy following exclusion of grazing animals. Photo David Norton.

 

Lessons learned. Important lessons learned over the 15-years have both shaped the approach to management at this site and have implications for the management of other projects:

  • Control of browsing mammals, both domestic and feral, has been essential to the success of this project. While domestic livestock were excluded at the outset of the project, feral Red Deer and pigs have the potential to seriously compromise restoration outcomes and these species have required additional management inputs (fencing and culling).
  • Since removal of grazing, the dominant exotic pasture grasses, especially Cocksfoot (Dactylis gomerata), now form tall dense swards. These swards severely restrict the ability of native woody plants to establish and herbicide control is used both pre- and post-planting to overcome this. During dry summers (which are common) the grass sward is also a significant fuel source and the walkway is closed during periods of high fire risk to avoid accidental fires which would decimate the restoration project.
  • Regular monitoring is important for assessing the biodiversity response to management. Annual photo-monitoring now spanning 15-years is highlighting significant changes in land cover across the site, while more detailed monitoring of plants and birds is strongly informing management actions. For example, seven-years of bird monitoring has indicated an ongoing decline in some native birds that is most likely due to predation (by cats, mustelids, rodents, hedgehogs). As a result, a predator control programme is commencing in 2019.
  • Simply removing grazing pressure from areas of existing regenerating native woody vegetation cannot be expected to result in the return of the pre-human forest because of the absence of seed sources. Permanent plots suggest that Kānuka is likely to be replaced by Mahoe (Melicytus ramiflorus), with few other tree species present. Gap creation and enrichment planting is therefore being used to speed up the development of a more diverse podocarp-angiosperm forest canopy.
Kate Pond on the Tiromoana Bush walkway. The pond and surrounding wetland provides habitat for several native water birds. Photo Jo Stilwell.
The pou whenua on the coastal lookout platform looking north up the coastline. Photo David Norton.

 

Looking to the future. Considerable progress in restoring native biodiversity at Tiromoana Bush has been achieved over the last 15 years and it seems likely that the project will continue to move towards achieving its 35-year outcomes and eventually realising the long-term vision. To help guide management, the following goals have been proposed for the next ten-years and their achievement would further help guarantee the success of this project:

  • The main valley floor is dominated by regenerating Kahikatea (Dacrycarpus dacrydioides) forest and wetland, and the lower valley is dominated by regenerating coastal vegetation.
  • At least one locally extinct native bird species has been reintroduced.
  • Tiromoana Bush is managed as part of a wider Motunau conservation project.
  • The restoration project is used regularly as a key educational resource by local schools.
  • The walkway is regarded as an outstanding recreational experience and marketed by others as such.
  • Tiromoana Bush is highly valued by Ngāi Tūāhuriri.
Kereru, one of the native birds that restoration aims to help increase in abundance. Photo David Norton.

 

Stakeholders and funding. The project is funded by Transwaste Canterbury Ltd., a public-private partnership company who own the landfill and have been active in their public support for the restoration project and in promoting a broader conservation initiative in the wider area. Shareholders of the partnership company are Waste Management NZ Ltd, Christchurch City Council and Waimakariri, Hurunui, Selwyn and Ashburton District Councils.

Contact Information. Professor David Norton, Project Coordinator, School of Forestry, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand. Phone +64 (027) 201-7794. Email david.norton@canterbury.ac.nz