For the vast majority of the history of public works, a tree and a bridge might as well have existed in two different worlds. The bridge had blueprints, a maintenance timetable, a depreciation schedule, and a secured place in the city’s financial plans.
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The tree, on the other hand, had a caretaker who understood its particular characteristics, whether a parks officer, arborist, or gardener. They could spot the signs of a tree in distress long before any spreadsheet could, yet rarely enjoyed the funding needed to act on that knowledge.
One was considered an asset; the other, at most, was an amenity: something pleasant which softened the hard edges of the city but was never truly trusted in writing to have any real importance.
That old divide now seems less like a policy choice and more like a mistake.
When you add them up, infrastructure accounts for over 70 per cent of global greenhouse gas emissions, according to UNOPS, UNEP, and the University of Oxford, and about half of all resource use and waste. Even more remarkable is that 60 to 70 per cent of the infrastructure the world will need by 2050 has not yet been built.
Each wetland, urban forest and rain garden overlooked during this expansion may ultimately need to be replaced by another hard asset, something poured, welded, or bulldozed into existence. Often at greater capital and operating cost and with increased long term risk. Nature is not an alternative to infrastructure; it is infrastructure that has too often gone unrecognised, without the plans, funding and management frameworks afforded to traditional assets.
This is the gap that IPWEA’s Green Infrastructure Management Manual seeks to close. Funded by project partners and the Local Government Research and Development Scheme, administered by LGA South Australia, the manual has been shaped by expertise from public parks, urban forestry, landscape architecture, and engineering. Its purpose is quietly revolutionary: to take the asset management discipline refined over more than a century for roads, pipes and bridges and extend it to trees, ponds and dunes. It does not create an entirely new framework; it thoughtfully adapts one that organisations already know and trust.
A valuable aspect of this approach is that it deals at once with the question which has hitherto restrained green infrastructure – namely, not whether it is valuable, but rather how an organisation should look after it, how it should fund it and how it should remain accountable for its condition over time.
It is here that the genuine and more interesting work starts. Rather than attempting to persuade people that a wetland is important, the focus is on enabling an ecologist, a chief financial officer, and a director of engineering to use the same language when discussing it.
For a long time, different professions have dealt with this situation using their own jargon and intuition, and one of the more subtle achievements of this manual is the careful development of a common language in which all can participate. The language applies to everyone, so there is no need for anyone to translate their expertise to be understood.
The kind of practical change that then takes place is something that every asset manager is used to: first of all, find out what you have, examine its condition, decide on the level of service it should provide, plan out its entire lifecycle and then provide the necessary funding for it.
The City of Marion in South Australia has created a comprehensive digital record of its urban trees, covering details such as watering schedules and inspection records, and operates a rotational pruning scheme based on this data. In Vancouver, the continued health of its urban forest is treated as an ongoing factor in the renewal planning process rather than being the subject of a once-every-decade survey. Melbourne’s urban forest strategy has set firm, funded targets – raising canopy cover from 20 to 40 per cent by 2040 – with the same level of seriousness that a council would bring to a bridge replacement project.
In the Canadian town of Gibsons, natural assets are given a monetary value equal to the cost of an engineered substitute, which is a quietly radical step because it enables marshes to be understood by accountants. What links these examples together is not merely good practice but good practice that has been demonstrated across different countries.
It is because asset managers in regional New South Wales can find comfort in the decisions taken in British Columbia that case studies are shared.
At the heart of all this lies a change in the way we conceive of time. A road’s service potential erodes over time unless it’s actively managed through its lifecycle, but a well-looked-after tree, wetland, or urban forest can increase in value if proper care is given – it can expand its canopy, improve habitats, steadily provide ecosystem services, and boost the health and overall vitality of the surrounding communities.
To regard natural assets as real assets is not merely sentimental; it is a more thorough form of accounting, one that asks not only what an asset is worth but also what kind of community and city the careful management of that asset can produce.
