Our collective Taonga: Urban forest plan

A plan for the future of Auckland's urban forest

Challenges facing the urban forest

This section sets out the issues and the consequential challenges facing Auckland City's urban forest now and into the future. It is based on our current understanding of the urban forest, the wider open space trends identified in 'Places for People, Places for Nature' that impact on the urban forest, international and New Zealand research and discussions with stakeholders.

2.1 Consolidating data, information and knowledge

The information held by council about the public urban forest is limited and incomplete. Work is underway to record species, condition and age information in a database about the street trees and park trees so that the organisation can complete a tree asset management plan. Based on the partial capture of information it is estimated that Auckland city has 70,000 street trees and 50,000 park trees.

The information about the private urban forest is limited mainly to the significant trees that are scheduled or protected in Auckland City's District Plan and in ecological areas.

The current information held does not allow a complete picture of the canopy extent, age, condition, structure or sustainability of the urban forest. A comprehensive information set would inform the development of a geospatial tree map and completion of an asset management plan for council trees that meets accepted industry standards. This dataset could include:

the extent of the overall tree canopy and vegetation structure of the urban forest
local native ecosystem;
changes to the private urban forest
council-owned trees.

Improved information would support an analysis of Auckland city's tree canopy against international guidelines. A tree canopy target would take into account Auckland's unique mix of climate, geography, land cover and land use patterns, but in general terms for a sub tropical climate like Auckland, the guideline for the urban tree canopy in suburban areas is 35 per cent [6]. Information is not available to support this analysis currently but it is likely that the guideline would not be met in all of Auckland city's neighbourhoods.

Comprehensive information would also support an assessment of the carbon stored in Auckland city's urban forest and a better understanding of its contribution to the city's sustainability.

A better information base is essential for the measurement and monitoring of the environmental, cultural, social and economic benefits of the urban forest and decision making by communities, agencies and groups. It will also allow Auckland City to improve how we fund and manage our tree assets and natural areas.

2.2 Creating connections and cohesion

Auckland benefits today from the plantings undertaken by previous generations. There are many places of special character in the city such as The Auckland Domain, Monte Cecilia park, Tahuna Torea nature reserve, Waiatarua wetland reserve and the pohutukawas lining Tamaki Drive.

The different approaches taken over time and in different areas of the city have resulted in some neighbourhoods being more green and leafy than others. The outcome is an urban forest of inconsistent character and coverage and with limited connections across the city.

The urban forest can play a part in delivering quality urban design for the city. There are opportunities to develop the city's urban forest in a way that defines Auckland as a Pacific city, reflects the character of the landscape, includes tangata whenua values and celebrates the city's communities.

The challenge is to create a more connected and cohesive urban forest that builds on our amazing natural landscapes and heritage.

2.3 Responding to the pressures on the urban forest

There is a range of pressures threatening the urban forest associated with the city's urbanisation, growth and development.

The pressures include:

population growth and changing urban form, which have resulted, particularly in the last 20 to 30 years, in increasingly dense development of the city. This has resulted in a cumulative loss of forest with pressure on existing vegetation and the ability to plant new trees [7]
the expansion and development of infrastructure and utility networks
the spread of weeds
soil and air pollution [8].

The challenge is to respond to the pressures on the urban forest, managing potential conflicts, ensuring that the forest flourishes and grows.

2.4 Enhancing the contribution of the urban forest to Auckland city's environmental sustainability

The urban forest provides significant environmental benefits including heat island reduction, contribution to green house gas mitigation, stormwater amelioration, particulate removal from the air, and habitat for birds and other fauna.

Internationally, the loss of exposure to natural biodiversity by city dwellers is considered to result in reduced understanding of nature by younger people and the subsequent undervaluing of biodiversity and the environment [9]. This has been observed by parks staff working with children across the Auckland region over the past fifteen years.

Traditional urban ecosystem restoration programmes have focused on continuous wild life corridors. This model is based on the movement of native mammals along those corridors. While some aspects of this model will support a fragile avifauna, it is likely that a model that considers alternative forest patterns more relevant to Auckland will need to be developed. A model appropriate to a New Zealand urban landscape is based on a series of biosustainable forest patches (ideally of about 6 hectares in size) which can act like a series of islands, linked by smaller areas which serve as stepping stones and feeding stations [10].

The challenge is to enhance the contribution of the urban forest to Auckland city's sustainability. This includes the development of measurable targets on the protection, recovery and recreation of viable ecosystems and in addressing climate change.

2.5 Engaging communities

There are complex and often competing interests to consider in plant, shrub and tree planting and management. Currently, community engagement in the public urban forest occurs principally in local decisions about the selection of street trees or the work that occurs under partnership agreements for the management of native forest areas and in community planting days.

There is an opportunity to engage stakeholders and communities more widely in a shared understanding of the benefits of the urban forest and in plant selection and management. This will achieve wide community benefits for the city and community engagement with the natural environment.

A comprehensive community engagement process for plant selection could be based on:

city wide objectives for the urban forest provided in this plan
values of tangata whenua in establishing culturally relevant species
geological and ecological character areas of the isthmus
individual and neighbourhood preferences
site limitations, utility constraints, soil types and condition, and local climatic conditions
reflecting and creating cultural and natural landscapes.

An aware and engaged community will understand the value of the urban forest, including on privately-owned land. The challenge is to educate and engage stakeholders and communities in plant selection and management and gain their support in delivering a thriving, distinctive urban forest.

6. American Forests CityGreen and based on Brisbane City Council's canopy target.

7. ACC consents for tree removal.

8. Esler, A. (2004) Wild Plants in Auckland. Auckland University Press

9. Identified by the International Union for Conservation and Nature through its working party on the urban imperative.

10. Meurk, Hall May 2006 Enhancing Forest Biodiversity across New Zealand.

Published February 2008