Future Urban Trees
The Biological and Political Life Cycles

C.Williams
Landscape Architect

ABSTRACT

A sustainable future for Urban Trees is becoming more tenuous. New strategies for effective management of mature trees, and the establishment of future ‘green city’ concepts are required due to increasing urban density, shorter political and fashion ‘cycles’, and highly modified urban soils.

The large ‘heritage’ urban trees seen today are probably the last large trees, ever. When designing cityscapes continuing to regard these and younger trees as ‘appendages’, rather than primary elements, will lead to stark unfavourable outcomes. Also, with intensification there will be an increased transference of space and responsibility for trees from the private to public realm. A concerted, integrated, non-political, long-term, well-funded ‘organisation’ is required to sustain a ‘productive’ tree population.

Trees require the highest priority in the urban planing and design process. This involves specific spatial decisions, generous implementation processes and effective ongoing management to meet design, technical and biological parameters that can sustain growth to achieve a ‘fourth dimension’ (change in form) over long periods. The cooperative, professional approach to ‘urban design’ creates the opportunity to achieve integrated strategies. With the definition of tree themes eg Ecological corridors, green fingers, urban forests, park ‘plantations’, street tree ‘islands’, broad shady avenues, residential shade/amenity, exotic and indigenous species amongst other design and economical management will be more assured.

The following paper follows the illustrated Forum presentation. It reviews historical and current approaches to urban trees and recommends a future direction to achieve productive ‘living heritage’, designed for comfortable, healthy city environs.

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BIOGRAPHICAL
Chris Williams as a Landscape Architect in private practice has a long-standing passion for trees. He studied horticulture and practised as a landscape contractor before studying LA in Melbourne. His broad experiences and observations have allowed focus on assessment and research identifying issues of ‘urban design’ on trees (at Melbourne City), and the supposed tree damage to road structures. He uses this deep interest in trees to speak at conferences; has advocated for tree protection as a past member of the Tree Council (Auckland); advised on tree educational programs; and has overseen a city’s tree program. Practical design of urban streetscapes, parks, gardens, rural production and natural restoration programs, and the scripting of management plans (including Eastwoodhill Arboretum) support the wider interests, as does his extensive travels which includes study in urban, productive and natural contexts. He is a member of the International Dendrology Society and other tree forums.

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FUTURE URBAN TREES
Consider that the large trees seen in the urban environment today are probably the largest trees that any generation will see, ever. Short-term political decision making and fashion ‘cycles’, do not give effective regard to the time, space and biological imperatives required for trees to mature. With a goal of a future with a range of large and elderly trees there is a need to wrestle back space from other urban infrastructure, raise the status of the tree and facilitate effective management. Urban tree management is more about space and overall landscape management than trees themselves. It is the incremental and cumulative impact of all the built ‘elements’ and physical changes in urban spaces that means purposeful and healthy tree, or not.

My observations and experience are varied. Grandfather settled on a steep dry East Coast New Zealand sheep farm in 1905. He built next to a patch of remnant bush and planted a park-like range of exotic tree species, plus large plantations of mainly eucalypts as future farm materials and shelter. My father instilled a respect for our little remaining indigenous bush, as well as the amenity, production and functional values of trees. We planted soil conservations species to reduce erosion, provide shade and fodder for stock with forestry species on ‘ungrazable’ areas. This inventive and sustainability ethos led my brothers to diversity and integration of horticultural crops eg tunnel houses, grapes, citrus.

I studied commercial horticulture management, with practical experience in parks and landscape restoration in UK and US. An early management plan was for the now internationally recognised Eastwoodhill Arboretum, the largest collection of Northern Hemisphere and temperate trees in the Southern Hemisphere. I worked as a landscape contractor in urban and rural Auckland and was involved in tree protection advocacy. I then returned to study and worked as a Landscape Architect in Melbourne, living both in Central Melbourne and the bush. Trees have been a passion, and I have been involved in such tasks as urban tree issues for Melbourne City, researched supposed structural damage, overseen a city’s tree plan, devised community-based training, and planned restoration and management programs for exotic and native environs.

This discussion is based on an initial presentation to the NZ Institute of Landscape Architects ‘Looking forward to Heritage Landscapes’ Conference at Dunedin, in April. It is a NZ perspective – but my views are formulated on experience and observation in urban Melbourne and Auckland. The objective is to raise awareness and advocate that the landscape and associated professions re-acquaint themselves with the importance of trees and urban greenery as a major component of their work.

Trees create an ever changing and commanding visual in the landscape while performing vital physical functions. They have the ability to inspire, soothe and sustain. Yet, people lose track of their greater significance within the natural and human ecology – the tree being regarded as the long-term symbol of nature.

Taking trees for granted can lead to tenuous futures. Trees present multiple values, and form a major component in the character and well-being of cultural urban landscapes. Many facts and fables about trees mean we are never quite sure how to react. Compounding this dilemma is the falsehood that ‘trees are easy to replace!’

We collectively have learnt so much about managing trees. But have we got what we want? It is my view we are in a serious state, and the issues in NZ are possibly very similar to those in Australia. The Tree Forum is timely. It advances the debate as our colonial heritage landscapes come to fruition, and we look forward to future generations.

This paper involves three main themes – Tree Protection Methods, current issues and a proposed format for future tree management.

TREE PROTECTION
Aucklands existing ‘Tree Protection’ methods were advocated by the Tree Council Auckland 25 years ago who aligned their direction with that of the Tree Council in Britain, and referred to the Sydney Tree Protection Orders. NZ local authorities had no real record of managing trees under a ‘legal’ framework.

They acknowledged that gaps and lost opportunities were appearing amongst the fine examples of cultural and heritage landscapes of parks, streets and residential gardens. Expanding road networks and rapid suburban development continued with variable results. Most particularly, was the wholesale change in established residential areas caused by ‘infill’ concepts. This intensification pressure continues.

The protection system proposed mediation and discussion before plans were drawn and chainsaws used. They argued trees of a size became community assets, as they are seen, enjoyed and provide benefits over greater areas than just the space on which they grow. After all, landuse has always had some form of impediment to free use. Their advocacy was successful in that a legal framework was developed under the Resource Management Act 1991 RMA.

The RMA considers trees within Section 6 Historical Heritage and Sec 7 Other Matters –eg Maintenance and enhancement of amenity values and quality of the environment; and Intrinsic values of ecosystems. The intended hierarchy of policies eg National, Regional, miss specific reference to trees. It is the District Plans Heritage Section that give weight to trees as an element for consideration. Generally, this only includes policy and Schedules of Notable Trees – trees ‘assessed’ for historical interest, landscape value, size/age, or rare by type.

In addition, a few Councils added ‘blanket’ protection ordinances. Two different approaches have 3developed in Auckland only. A) All trees are protected over (6-8m) in height depending on landuse zone, whether it is a slow growing native species or an exotic – this includes a list of exceptions eg weedy, fruits, transportable types. B) Specified lists of exotic species and or natives at say 6-8m in height, which may be relevant to specific zones. These systems seem to have made a difference although there is little quantitative evaluation.

The problems arise as some districts have control-oriented, time-consuming and costly to administer rules. Others lack consistency in approach (or have no planning mechanisms), staffing, technical standards, and educational material. There can be adversary arguments between professionals, arbitrary site planning requirements, difficulty in adopting appropriate building codes and engineering systems to suit site constraints (thereby adversely affecting trees or remaining soils). The standard building system is a concrete slab floor rather than the less intrusive and flexible stump construction. These dilemmas have bred confusion and reluctance for full buy-in. Even tree ‘practitioners’ have not adjusted to different local authority nuances.

A much needed revision of a ‘conservation’ or ‘protection’ scheme needs to canvass, evaluate and develop different kinds of incentives, ‘trade offs’, compensation or legal mechanisms. These approaches are implicit in the effects-based planning concept of the RMA but not yet fully developed. For example:

• Transfer development rights, variable building densities within a zone, replant before removal
• Greater publicly owned trees, reserve contributions, multiple replacements within a given area
• Covenants, private reserves, rates (land tax) relief, (currently bush remnants can attract rate relief – why not significant urban trees)
• Performance bonds, management plans and legal agreements
• ‘Enforcement’ systems to ensure success (eg for 5-8 years or until trees are stable or become ‘protected’)
• Or a combination

The method of only relying on a District Plan Schedule of Notable Trees as the only afforded protection creates elitism. It discounts other worthy, or ‘near mature’ trees, and the life cycle of trees. The principles of conserving life, association, example and the biological requirements – space, food, water, air, etc. are all so important - all trees deserve discussion. Whatever a system may be, it requires simplicity and wide spread acceptance – most importantly promote desirability, benefits and good practice (- carrots rather than sticks).

A robust tree management system also requires an accepted and consistent evaluation (assessing landscape merits) and valuation (assessing monitory value) systems. The Royal New Zealand Institute of Horticulture has developed and promoted various systems over the years. The current template Standard Tree Evaluation Method (STEM) endeavours to combine the two requirements. Unfortunately it has not generally been accepted and adhered to. Auckland City developed a favourable method to evaluate and select trees for additional status (over general protection) and scheduling under the District Plan rules. It was designed for an arborist/tree specialist and a heritage planner or landscape architect together. These two views complement each other, - reviewing specific tree aspects and the relationship with setting or city landscape values. However it has not attempted to assign dollar value.

Attaining agreement on a consistent methodology for assigning dollar values to living objects is long overdue. Requirements for asset valuations means tree values, costs, depreciation, should also be considered along with other urban infrastructure. Structures are built with a 40 years ‘design life’ and last for 70. Yet a tree with a desirable and capable 150-year ‘design life’ can be damaged, or removed within 30 years, or less.

Tree ‘protection’ mechanisms in NZ are inconsistent among local authorities. Also, there are a variety of attitudes, expectations, and design standards within different industry sectors (eg utility companies, roading authorities, and professions) that heavily influence the quality of urban tree cover. Trees become the ‘forgotten’ or problematic element in a decision making process, as different sectors assert authority, or look for competitive advantage.

Within the urban intensification planning process, the productive results sought are not being met. Too many trees still fail, particularly after 3 to 8 years following a ‘protection event’ or replanting associated with a change in land use. The speed of the ‘fashion’ cycle (change of landuse and ‘style’) imposes constraints that means tree replacements have little chance of attaining a scale and form of the older trees being lost, because of species type and inappropriate soil conditions.

CURRENT ISSUES
Issues concerning trees in urban locations are diverse and complex and cannot be resolved in isolation. Often interrelated or interdependent questions need consideration.

Political indecision or a lack of long term commitment to trees is exacerbated by rapid increases in urban density, short political and fashion cycles, and highly modified urban soils (as above). Trees are treated as ‘appendages’ rather than principal elements in the planning and management cycle of the urban fabric. Too often, they exist in suspended animation, wanting to live, waiting to die! As older trees are removed, the young ones are not always performing as planned. Any continuation of neglect of the long-term biological provisions required for trees to mature and sustain gracefully is likely to lead to greater down-scaled and decline in effective, healthy tree cover.

The pressure for urban development and intensification continues to heave attention onto the mechanics of the protection concept, or in other locations an absence of any conservation strategy. Most agree the intent of ‘protection’ is right, but the older trees are still going down. The landscape change needs to be managed and monitored, as observations suggest newer generations of trees are struggling. Trees are labelled as poor, dangerous or inappropriate species, or they 'die from a thousand cuts’ because of a lack of definition, direction, and space or from improper activities.

At a higher level, debate could take two directions: man impacts enough on natural systems and living structures. Are we doing enough to conserve what we have? Alternatively, people have property rights, and land use changes are fact. This argument reflects we ‘know’ a lot about how trees/nature works, so we can always ‘reconstruct’, in this case, the tree cover. Two other big reasons to further enhance our tree populations are the intent of the Kyoto protocols to encourage carbon soaks. The logical direction is to try to centre this ‘soakage’ at source. Related are the study, research and measure of benefits of clean, green environments on human health and well-being. Olmstead in the late 1800s referred to trees as the ‘solace and comfort’ for the stressed minds of urban dwellers being more important than the air purification or amenity values. Trees are a ‘complementary medicine’ in a healthy, vibrant city.

As well as not doing so well looking after our existing trees, in many landscapes, despite knowing how to reconstruct, we are not establishing enough ‘productive’, healthy, vigorous, replacement trees. We select inappropriate species for urban ‘deserts’, or do not allow for or prepare the space. We are desperate to retain something natural in the city, but things have to be new or fashionable. We turn our back on the tried and tested design principles of the past and our understanding of how nature works. It is, as if the issues are so big we have to shrink-wrap them into little parcels, meanwhile loosing sight of the overall system we wish to conserve and enhance. Subsequently the whole tree cover will shrink.

Selected specific issues worthy of priority consideration:

• There is a general acceptance of the importance of trees and for some form of ‘protection’ system. New parks are designed around old trees; intensive housing is intensely planted; street trees are installed as part of subdivision requirements; the community revegetates the gully; a huge selection of trees are still available. However, to ensure adequate supply in the intensified urban, it is highly likely public authorities’ responsibility will increase.
• Trees over a certain size become a ‘community asset’ and transcend the average property ownership cycle - reported as only 7 years. Trees are desired to screen, soften, and provide scale and effect. The average life of a street tree in USA is 10-15 years - due to climatic or conditional stresses.
• Urban intensification moves away from the pioneer ‘quarter acre pavlova paradise’ concepts as the cost of urban impact, spread and sustainability questions rise. With this intensity and division people lose connection with ‘nature’. Life becomes compartmentalised and fragmented and policy development looks more short term. This short-term political lifecycle, the constantly revising of strategies affects long-term objectives. It has been easier to get $250,000.00 to build a toilet block $100,000 for art works, than the $30,000.00 to ensure the planting of long-term structure of a new park or street.
• A recently released high level document - Urban Design Protocol - UDP- supported by the Ministry for Environment has few references to vegetation, and then only with regard to biodiversity or about ‘natural’ green corridors. As a way forward for the design and management of urban intensification the concepts and processes are enlightening. But green matters, even if implied within policy like the UDP, need deeper reference, thought and therefore space and funding.
• It is fashionable for park redevelopment, green or brown field developments, and within Mainstreet (Town Centres) programs to create wholesale change rather than designing with respect to the long term elements. An Auckland Mainstreet has plane trees (and paving) 20 years old and the current concept is to remove these and replant with Nikau palms (native Rhopalostylis sapida) as ‘iconic’ symbols of this place in the South Pacific. The new species has a fashionable feel - but scale, shade, canopy spread and visual effect, survival, appropriateness in rows in the concrete canyon seems problematic. Similarly, in other town centres deciduous canopy trees have been removed and replaced with palms in tree boxes, as leaves got in the gutter and unit paver surrounds were heaved – both problems easy to manage.
• The massive community based revegetation programs using native species in or near the City are politically projected as the panacea for the declining tree cover or bareness where people live. The ‘natures out there, we live here’ concept may dominate, rather than an integration of urban and natural systems.
• The art of appropriate species selection to match the conditions and thematic outcomes is very important. Any debate about exotic versus indigenous species tends to hijack reasoned design intent on achieving ‘productive’ and site appropriate results. Forest trees that depend on symbiotic ecological relationships do not survive well as specimens in dense ‘concrete deserts’ and lifeless, compacted soils. And in cul-de-sacs we plant large exotics (eg plane trees), that will overgrow the design objective. This therefore requires effective definition of vision, design and specific technical requirements for each theme, along with long-term management programs in order to de-confuse and educate professionals and the wider community alike.
• The utility companies have developed criteria for managing trees around ‘their assets’- many of which are highly questionable, nor assessed against amenity or public good values. In-ground lines either damage root systems or are so prolific trees cannot be planted. Trees are being compromised and made unaesthetic by implementation of heavy handed standards for lines clearance. The roading authorities in one sense want trees designed in for traffic calming principles or removed for fear of accidental impalement. Occupational, safety and health and insurance driven parameters are dictating landscape values - or tree removals as they ‘maybe dangerous’.
• Those professions that have responsibility for or whose work affects trees are diverse. What was the domain of the ‘parks department’ is now divided between specialists and tree ‘experts’. Discussion and common language is necessary.
• Urban renewal or expansion is often inconsistent with ecological, hydrological, and horticultural principles. Soils are becoming highly modified, affected by heavy equipment creating compaction rates of an engineered fill - problematic for root penetration and ultimate growth. We have to understand that within every development, soil conditions will be different to when old trees were planted in the era of the horse and cart. These compacted soils, often without natural profile, could support growth if effective soil fracturing, provision for oxygen and drainage, and other horticultural techniques that extend well beyond the planting hole.
• Greater emphasis is required for the principles of ‘retain, manage, replant and then remove’ when redeveloping land. The ‘norm’ has become removal and replacement no matter the age or type. Unfortunately, examples exist where planting for replacement becomes less than adequate, as ground preparation and wind protection for large grade planting stock is not achieved.
• Other technical standard specifications and processes need revision, eg maximising stability of young trees; the use of flexible and porous surfaces around trees; construction methods that allow root development, etc. Trees can be forgiving but how much stress can they take especially from works within their zone.

On balance, one of the most serious threats to the landscape and its trees is inconsistency in approach. This can be under public and legal mechanisms, within allied professions, design approaches and implementation specifications. And there are conflicting or competing community values, attitudes and demands for urban trees. Revision is urgently needed.

A WAY FORWARD
New strategies are needed now to ensure stability for mature trees, and re-establish the future ‘Green City’. A collaborative professional model is preferred (similar to that as promoted for urban design). A concerted, integrated, non-political, long-term, well-funded approach is required to sustain a productive and economical tree population.

Any strategy requires national leadership to provide consistent guidance and templates. Local authorities would become more assured with systems that build on and adapt these overarching principles to suit local requirements. The allied professions would promote quality standards. This approach would assist the public to understand and appreciate vision and direction.

The new strategies would not be to ‘green everything’. Hard spaces are a fact in a city. The intent is for a healthy, productive, dynamic and affordable tree cover effectively combining and balancing the forces of ‘politics’ (decision making) and the long term ‘biology’ (life forces) pertaining to urban vegetation.

The complexities of growing trees are too diverse to be managed by one profession. After all, effective tree management deals with competing forces – people, built structures and trees. Therefore, a ‘tree team’ must balance economic, planning, design, and specific spatial aspects with technical implementation, biological parameters and management processes to sustain growth over long periods. Tree management is largely ‘space management’.

Trees, as natural objects, respond to conditions in which they grow. They perform a variety of functional roles and character or aesthetic themes. By defining the different purposes and types of vegetation, would provide greater understanding of the nuances of each theme and subsequently the correct and targeted budgets and management programs to suit.

The themes to be defined (but not limited to) may for example be:

• ecological ‘corridors’ - riparian strips, rivers, wetlands, hill tops and valleys revegetation, including managed native remnants - in a natural sustainable form and size
• green ‘linkages’ - areas of mixed species and use that create networks for wildlife, recreation/ movement through the city, - (including motorway corridors)
• urban ‘forests’ - an American term used to describe all urban trees to foster the concept of management and renewal. This could also mean market driven ’forestry’ to allow for alternative recreation opportunities, carbon sinks, green belts
• park ‘plantations’ – more local intensive structural planting of parks
• street tree ‘islands’ - reasonably sized areas totally remediated for dense planting to create impact at points like traffic islands, wasted corners, interchanges
• broad shady ‘avenues’ - the traditional individual specimens in rows
• residential ‘amenity’ – varies from local parks, squares, courts and the views from apartments, to complex landscapes and traditional ‘gardens’
• plus seasonal shade, ‘beautification’, wasteland ‘rehabilitation’, temporary ‘crops’, among others.

Each theme would have:

• specific design and implementation standards to achieve the desired results eg space needs, soil remediation/conditions, establishment techniques, spacings, species selection
• the ongoing management plan and works specs, tagged and attached to the space to achieve the specific design intent and criteria
• the planning criteria for the lifecyle of that landscape or individual trees
• projected budget requirements linked to lifecycles.

SUMMARY
The current situation for urban trees is declining. Many alternative methods are available to move forward. First we need to look back for methods worthy of revision. However, there is no time to invent. Future strategies must be consistent, comprehensive, educative, pro-active enduring visions, well funded and reasoned. While there needs to be a legal framework, this would sit behind the new ‘Plan for Trees’. The main thrust will provide flexibility, incentive and encouragement to all sections of the community.

Urban Tree Management is a matrix that involves complex ‘lifecycle’ and often-competing forces.

Balance - the environmental, social, cultural and economical, values.

Short-range political decisions must balance long-term biological parameters

With the
Planning – vision, frameworks, performance criteria
Design – principles (both enduring and new systems), details, implementation
Management – space, protection, replacement, removal

And the
Social – people, cultural values, aesthetics
Trees – nature, natural process, dynamics, movement, change
Structures - rigid constraints, man made structures, economics.

The Framework for review and ongoing management would follow:

NATIONAL RESPONSIBILITIES – (PLANNING LEVEL)
Create a central agency to:

• Develop ‘legal’ frameworks, mechanisms and ‘performance criteria’
• Coordinate research and standards (define themes, lifecycle planning and design principles, valuation methods, specific implementation techniques and tree care practices)
• Coordinate impact of utility companies and other ‘authorities’ – management of public space
• Sponsor, promote, educate and disseminate information
• Retain overview, create opportunity, provide templates, guidance and forums

This agency may be a ‘Department for Trees’, or within Ministry of Environment or Local Government. It would desirably maintain an apolitical, long-term vision and work across ‘boundaries’. At both the national and local level there is a need for balanced multi-disciplined groups of professional partnerships or collaborative associations:

‘ TREE TEAMS’

• Designers - Landscape Architects / urban designers – bridging between the arts and sciences, theory and practice
• Specialists - arborists, horticulturists, plant pathologists, ecologists,
• Space Managers - parks officers, engineers (civil, structural, utilities), foresters,
• Planners – strategic, resource consents, heritage (natural, cultural, historical)
• Legalese – government legislative, insurances, safety, valuers
• Social – the Community / public relations advisers

Each must acknowledge the different skill sets within the professional groups.

INDUSTRY RESPONSIBILITIES - (DESIGN/IMPLEMENTATION LEVEL)
Establish quality standards for product and services:

• Planning visions
• Design principles and advocacy
• Specification standardisation
• Nursery growing standards
• Tree Care Specialists – Arboricultural standards
• Contractor implementation methods
• Specialist soil and building material suppliers
• ‘Quality assurance’ - Self-regulation eg industry approved contractors and suppliers.

PRIVATE LANDOWNERS RESPONSIBILITIES
Grow abundant trees effectively to complement the public stock.

LOCAL RESPONSIBILITIES – (MANAGEMENT LEVEL)
Develop the local identity, specific requirements and administrative processes to:

• Maintain inventories and monitor
• Develop a comprehensive Tree Plan – includes objectives and policy for public and private trees, and requirements within development processes
• Provide regulatory, operational and enforcement
• Care for public trees
• Fund and staff
• Provide for general tree selections for location
• Promote professional services
• Provide assistance for Private Tree owners
• Support ‘Community Tree Advisors’ networks.

The improved care for trees over the last 20 years has been an achievement. We have come a long way - but have we gone anywhere? The recommendation is to raise the bar and manage urban space to provide for the biological requirements of trees and manipulate the political systems to suit. There is a great need to work freely and fairly together at different levels of urban decision making and management, and to find common ground for a comprehensive, sustainable and appropriate tree cover for our future (urban) well-being.

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