Dr. Karen Olsen


Who has not had a sinking feeling on discovering that the highly hazardous, structurally poor, uneven-canopied, failing or senescent tree in a local street or park is listed as being of heritage significance? Why does reality have a nasty habit of biting in the midst of our visions, dreams, plans and programs for developing and managing a better, future urban landscape?

For managers of trees, streetscapes and avenues, there is no doubt that the reality of respecting and responding to community and heritage values and obligations can be frustrating and individual’s or community groups’ actions can at times seem obstructionist. On the other hand, for heritage professionals, the very nature of the heritage fabric of trees as living, vegetative matter, might seem to add an annoying complication to the aims of heritage conservation to keep and care appropriately for culturally significant places we have inherited.

The idea that ‘reality bites’ reflects a range of potential responses to the issue of heritage and trees, anywhere on the spectrum from sharp cynicism to pragmatism, from wise hindsight to grim determination – or, usually, any combination of these, from stakeholders on all sides of a given situation. The aim of this paper is to understand why and how it is that ‘reality bites both ways’ in the tree management and heritage management. This includes recognising that the realities of both heritage and management by their very nature generate highly emotional responses and reactions. It also includes seeing that each of these realities can offer to its ‘opposite’ specific insights that can then generate a more holistic value for trees, streetscapes and avenues which is greater than the sum of its parts. In other words, reality biting can be a useful tool to help us look further than just the immediate problem at hand.

This paper is in three main parts. Firstly, it examines the values or basic thinking that landscape professionals and heritage professionals bring to the management of trees, streetscapes and avenues. It gives detailed consideration to heritage values in particular, for readers who may not be otherwise familiar with heritage conservation practice, approaches and terminology. Secondly, the discussion looks at how reality bites when the thinking of one ‘camp’ appears to collide or be in conflict with the other. Finally, the paper uses these apparent conflicts to reflect on some constructive propositions that might facilitate mutual benefits for each.


In the management of urban trees, streetscapes and avenues, standards for the assessment of amenity values, and especially financial values, vary widely, and are probably familiar to readers in many different forms and guidelines. Notwithstanding these variations, amenity values of trees reflect our appreciation and understanding of a range of elements or characteristics, which include: health and vigour, amenity/ aesthetic value (including qualities of height, canopy size and trunk diameter, age, form and location), environmental value, habitat value (for example, the relationship between indigenous species in a given context and associated fauna), and the future (for example, life expectancy, growth rate, and so on). These values are overlain with further considerations which include values – both personal and organisational – relating to cost (ranging from purchase and establishment costs to long termmaintenance and eventual removal/ replacement costs), hazard potential and also potential threats to the tree. Furthermore, this very brief initial listing expands much further when we consider particular criteria and specific instances. Terms or concepts which encompass or expand on many of the values above include those such as ‘outstanding example’ or ‘landscape or location context’.


How do these values compare with and relate to the values used in heritage? Historic trees, streetscapes and avenues form a significant landscape feature and have a large impact on the landscape, both visually and environmentally. They are part of what is known as ‘heritage’ or, as it has been colloquially described, ‘the things we want to keep’ (Parliament of Australia 1974: 20). According to the Australian concise Oxford dictionary, heritage is ‘anything that is or may be inherited’ (Hughes, Mitchell, and Ramson 1992). The need to keep and pass things on to inheritors is viewed by some as a ‘basic part of human nature’ (McCarthy 1996: 5).

Fundamentally, heritage conservation itself is built on the twofold premise that (a) there are places worth keeping because they enrich our lives, help us understand the past and contribute to the future, and (b) the cultural significance of a place is embodied in its physical material, use, its history and its past and present meaning to people. In Australia, ideas about cultural significance are articulated through legislation, government policies, and, in the most widely used cultural heritage guideline in Australia, the Australia ICOMOS Burra Charter (1999).

Values of cultural significance in the Burra Charter include historic, aesthetic, scientific, social and spiritual significance (Australia ICOMOS 1999, Article 1.2), and any place – in our case, trees or avenues – can be described and analysed as one or more than one of these values. These values vary from community to community, as well as having the potential to change within the same community over time.

Historic significance relates to a tree or avenue’s value for it association with important historical events, eras or individual people. Historic value ‘underlies’ aesthetic, social and scientific value (Marquis-Kyle and Walker 1992: 23).

Aesthetic significance accommodates all the sensory values of the place (but privileges the visual especially) and is often encapsulated in architectural terms, such as through a particular style. Trees and avenues are often considered aesthetic in their own right apart from issues of history or science, and old trees in particular are often considered venerable for their size and form.

In assessing the significance of trees, historic and aesthetic significance often interlink and inform each other. For example, as a commemorative (historic) landscape, Avenues of Honour exemplify historic significance through their particular aesthetic, since they are typically developed along the lines of what we often call in design terms a ‘power landscape’, using symmetry and repetition reflecting an ‘imperial aesthetic’ (Gough 1998) which specifically connotes of their commemorative purpose. On the other hand, it is the age or ‘oldness’ of the venerable tree mentioned above that often generates its aesthetic values of notable size and form.

Scientific significance relates to the technical achievements or factors associated with trees or avenues. For example, horticultural significance includes plant species which may be rare, endangered, or ‘old’, and these can be important not only as a nostalgic link but as a genetic resource (Hendricks 1999, Hummer 1999, Telewski 1999). To a lesser extent, horticultural techniques including methods of plant manipulation and cultivation – for example, pleaching or even pollarding – are also of scientific value. Some collections are scientific for their experimental value, and also related to historical individuals: early use of Tasmanian Blue Gums (Eucalyptus globulus) as street tree avenues in Melbourne in the mid-nineteenth century by Baron Von Mueller is a case in point. Habitat value, although increasingly recognised, remains a disputed application of scientific cultural significance (for example see Ihse and Norderhaug 1995) and is typically dealt with by other charters (for example see the Australian Natural Heritage Charter published by the Australian Committee for IUCN 1996).

The issue of determining social value highlights the complexities of heritage value. ‘Social value [can tend] … to mean all those values expressed by the community which fall outside … current professional frameworks’ (Johnston 1992: 4), and yet should be recognised and employed within the same parameters as, say, architectural or historical values and theory. Social value, or the ‘deep sense of attachment to place’ (4), is symbolic of community use even though the social value of a place is particularly subject to change over time (cf. Burra Charter, Article 1.2 explanatory note).

Like social value, spiritual value relates largely to abstract ideas associated with the physical fabric of a tree or avenue, often underpinned by historical significance.


Deciding which trees are significant and which are not involves a detailed process of physical inspection, (including consideration of ‘condition’ and ‘integrity’), contextual research, understanding of community values and comparative analysis against other similar examples and agreed thresholds and criteria. According to the organisation and ‘ownership’ of the particular assessment, specific assessment criteria are developed – for example in Victoria National Trust criteria differ markedly from Heritage Victoria criteria. These criteria are a specific articulation of the heritage values discussed above in more specific terms.

The cultural significance of a place is then compressed into a brief ‘Statement of cultural significance’, although for street trees this can be as brief as a check-a-box on a standardised form. In principle, this significance can be used to guide future management of the tree or avenue, and is recognised primarily through registration on a relevant listing, overlay or register. According to their purpose, such lists may provide legal protection (State Government of Victoria 1996), educational information (Goodchild 1990: 50), and/or warning of potential damage to or loss of a significant place (Bruce 1995), or advocacy for the same (Graham 1997).

Registers and lists operate at all levels, from the local community to nation- and world-wide, and by both government and non-government bodies. The most comprehensive street tree and avenue listings currently have been developed either as part of broader heritage listings (for example, the Victorian Heritage Register or the National Trust Register of Significant Trees), or in specific typological studies through local government whereby municipalities can protect and manage their ‘heritage canopy’.

It is worth repeating that understanding cultural significance enables not only insight to the values of a place, but also the means of protecting them. Furthermore, heritage principles argue that there is nothing less than a social and often legal obligation to protect such places for future generations, primarily through the activities of heritage conservation management.


The ‘conservation’ of trees and avenues really means the best appropriate care of these places for the enjoyment of present and future communities. Conservation means ‘all the processes of looking after a place so as to retain its cultural significance’ (Burra Charter, Article 1.4). ‘Cultural heritage conservation’ and ‘natural heritage conservation’ are usually dealt with independently of each other.

Conservation involves the marrying of conservation principles and actions to the site-specific significance and contextual issues of a streetscape or avenue to develop a systematic policy and program or plan (usually known as a CMP or Conservation Management Plan) and, above all, consistently requires judicious choices on the part of the practitioner. It means management and use with an ever-conscious view to the significance of the place and hence its conservation needs (see Kerr 1996, Goulty 1993).

Needless to say, the appropriate selection of conservation actions can become extremely complex when a range of these factors are at play, simultaneously, or perhaps in conflict, in a streetscape environment. Furthermore, matching the conservation principles and the site-specific significance for a garden is also always tempered by contextual management issues. Broadly, these contextual issues include: horticultural requirements at general and specific levels, environmental pressures, planning and financial issues, and visitor amenity.

Many of these areas of landscape conservation principles and practice are potentially fraught with difficulty for applied conservation purposes. The reality of historic garden management and conservation clearly forms a picture somewhat more complex in reality than that which the ideals of conservation may initially pose. In addition, programming of conservation works is influenced by a myriad of contextual management issues, which have the potential to make management choices more complex again. Issues such as species selection, maintenance, environmental contexts and changes over time to the urban tree environment, changes to technology and funding, and replacement and rejuvenation strategies, are all both fascinating and fruitful areas for debate of broader conservation management of the urban landscape environment, but cannot be discussed in any detail here.

For the purposes of this discussion though, of special interest here is the concept of minimal intervention to significant fabric. Colloquially speaking, this means doing ‘as much as necessary, as little as possible’ (Burra Charter, Article 3.1 and Preamble). This comes from the broader historical context of conservation being an architecturally driven endeavour, with a focus on ‘keeping’ or preserving fabric in as static a state as possible. Clearly, the very nature of vegetation as living ‘fabric’, renders typical architectural conservation processes and the very approach itself both difficult and undesirable in practical application.


When we examine the values of cultural heritage significance against those of amenity tree management, there are many overlaps and similarities. However, there are also some significant gaps. It is these gaps, I believe, that generate much of the angst and potential conflict associated with management of heritage values and trees in the urban environment.

The main ‘gaps’ between heritage values and tree management values lie at either end of the spectrum for each professional approach. In many ways, in practical management terms, these could be considered to be in direct opposition to each other. For heritage, the chief values of the tree or avenue seem to lie in its past and present – for example, ‘What is this tree’s history?’, or, ‘How long has it been valued in the cultural memory of a community?’ – which then guides its management for the future. Most importantly, the principle of minimal intervention demands, ‘How can we keep it this way? … and for as long as possible’.

Conversely, for urban landscape managers, chief values of the tree might be interpreted as lying in the present and future – for example, ‘How much will this tree cost to maintain?’, or, ‘How long will it perform well for?’, or, ‘What is its life expectancy?’, ‘What damage might it cause tomorrow?’. Urban tree and streetscape management demands a focus on the future environment, limiting risk and working within externally determined budget constraints.

Of course, the danger in simplifying this situation is that we risk ignoring the many compatibilities between the two approaches and reducing the values from each paradigm to the equation where, ‘heritage equals the past at the expense of the future’, and ‘urban tree management equals the future at the expense of the past’. This sets up an opposition or dichotomy between heritage and urban tree management which provides fertile ground for misunderstanding, conflict, delay and disappointment for all concerned.


On the other hand, this is where reality will always bite us back, and the gaps that cause so much angst can actually be productive ‘pressure points’ showing that a particular value system cannot work in isolation from others around it. It is the realities of both heritage and horticulture that demonstrates daily that working from the above equations (heritage=past, horticulture=future) can blind us to the opportunities offered by each of these fields.

The reality of tree management bites back for heritage professionals when the approaches offered by the former are ignored. Heritage has often been perceived as a ‘don’t touch’ affair, so that to do, ‘As little as possible, as much as necessary’, translates to doing nothing at all. Horticulturists and arborists, landscape architects and planners know that to do this is suicidal as a management practice.

The result can be substandard trees and streets, still managed for ‘heritage values’, when the very values that a tree was nominated for are long gone. In any historic landscape, no matter how venerable, the worst indicator possible is perhaps the site where there are no new trees at all.

These situations are more common than we would like to think, especially with regard to, but not limited to, street tree avenues. Poor and senescent tree specimens are often maintained at the expense of aesthetic value and public safety when they are considered part of a ‘heritage’ landscape (Parker 1998) and, crucially, are not conceived of in terms of renewable landscape elements (Hitchmough 1990 and see Hitchmough 1994 on public veneration of trees). Meanwhile, for commemorative plantings, the reality and hindsight of Avenues of Honour plantings show that species selection can determine the success or failure of an Avenue. For example, the use of small mixed Australian native plantings popular in the 1970s – Callistemons, Grevilleas and perhaps Queensland Brush Box – or even use of the fast-growing Sugar Gums, both result in memorial avenues that have a reduced sense of presence or longevity (or both), which is the very reason for which they were planted. Similarly, a Lone Pine with a bifurcated trunk, no matter what dignitary it was planted by, is still a Lone Pine with a bifurcated trunk – and reality will bite back one day soon.

Meanwhile, from the other side of the fence, the reality of heritage significance bites back for tree and landscape managers when tree replacement and management programming is undertaken with no regard for the immeasurable added value that heritage can bring to the equation. The principle purpose of planting and maintaining trees, streetscapes and avenues is at the very least to provide a better environment for human habitation. Heritage practitioners know it is suicidal as a management practice to ignore the abstract values, associations and meanings that we, as humans, bring to these environments.

The result is lost opportunity. Opportunities are lost when tree removals are undertaken with no understanding of or regard for community values or flexibility to respond to these community values, or when there is no understanding by the community of program objectives and processes. Opportunities are lost when the streetscape is ‘owned’ by the municipality or managed only as the trees which occur in the space between the suburban street curb and the footpath: the contribution of privately-owned tree canopy and the social space of front gardens or yards hold enormous potential as an asset for urban environment managers looking towards sustainable future solutions. It is often through the eyes of heritage that these values can be recognised and capitalised on. Opportunities are lost while the whole equation remains economically-determined; triple-bottom line accounting is discussed widely but rarely implemented, and heritage values offer some form of in-road to this rather resistant aspect of environmental management.


It is true that we need to look for the common ground and recognise compatibilities in values between heritage and tree management approaches. But, it is also important to recognise the gaps between professional value systems, and use these pressure points to push the boundaries of each profession to improve outcomes for both.

The benefit of reality and its capacity to bite, is that if we choose to ignore the values of either sound tree management or sound heritage management, both the future and the past will come back to haunt us. ‘Keeping things’ (a.k.a. heritage) and ‘growing things’ (a.k.a. horticulture) are actually two sides of the same coin, and that coin is one we have made. The challenge is to keep sight of the two sides of the coin, to view the streetscape ‘as both a historic resource and a recreational or aesthetic work in its own right’ (Mitchell & Pepper 1997), not to mention all of its other environmental and amenity functions.

What if heritage values could be more dynamic and responsive? And, what if tree management values could be more sensitive to community needs for ideas of permanence and stability? In particular I would like to propose for heritage the development of a specific vocabulary for assessing and managing significant vegetation, including a dynamic model for significance which is responsive to the cyclical nature of tree value, including specifying a category of ‘future significance’. This is a topic for a whole separate paper, but just one of several prospects available for mutual benefit.

Also needed for heritage is a range of detailed management approaches which are specific to each value of significance, so that heritage value itself – rather than just the physical specimen – is maintained and continued appropriately over time.

For tree management, genuine community consultation – not just saying, ‘Well, we letterboxed them’ or ‘did the public meeting thing’ – is another point for the agenda. Matching this is the need to share knowledge between all stakeholders, through the universal adoption of a ‘heritage’ or ‘community’ check box with a written explanation or analysis for every tree assessment spreadsheet.

For both tree management and heritage professionals, better communication, and greater inter-disciplinarity can generate improved understanding and, thereby, improved future management systems. And, in purely practical terms, heritage can afford to be more flexible in terms of smarter replacement species selection; while at the same time, tree management can be more open-minded to exploring old and perhaps now-unfashionable species.

Of course, it is important to acknowledge that many of the opportunities listed are currently considered or used in some tree and avenue heritage management, depending on the particular project and individuals involved. However, more can be done to cross-fertilize, educate and implement these as standard practices, to become familiar territory for everyone involved in the management of heritage values and urban tree-scapes.

Reality biting means that the tension between keeping things and growing things can be a productive one, used to stretch both paradigms. Tree management can help heritage to move beyond a static approach, to manage vegetation more flexibly and adopt a broader vision for continuing significance into the future. Meanwhile, heritage offers to tree management the opportunity to add meaning (to ‘value add’) to standard tree management, explore alternative solutions, gain improved understanding and support from communities, and provide an alternate view to potentially reductive tree assessment of: ‘Senescent specimen: for immediate removal’.


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