When we talk about the “urban forest,” are we are kind of kidding ourselves?
A forest is a complex biodiverse extended living organism that is:
- community engaged (plants, microbes, invertebrates, birds, animals)
- productive as a natural system
But a forest does not contain infrastructure as people know it. Mortgages, property boundaries, fear of damage from trees and legal responsibility or ownership over the human built asset and urban landscape prevail.
So can we really use the term "urban forest"?
There are competing issues here. The conflicting constraints of the urban part of the ‘urban forest’ as described above present another set of challenges to maintaining a balanced functioning forest. By its very nature, the merging of these two conditions open a new frontier of opportunity to manage the urbanisation transition and arrest a seductively slow decline in the urban landscape.
While science is continuing to progressively describe the complexity of the natural world, the competing forces of urban growth impinging upon natural habitat and ecosystem are constantly dynamic and not yet well understood. As people will not move away from urbanisation any time soon, it is imperative that another layer of scientific investigation and resulting management protocols are added in to the developing of the urban landscape. Grey infrastructure is placing increasing pressures on the green component of existing assets, and even more so in the design of new installations. This too often results in less than satisfactory outcomes for residents in the growing urban environment in the immediate future.
How important is data to the future of a healthy urban forest?
Knowledge and understanding through scientifically sound data accumulation is essential to manage impacts on the environment. Key data collection of spatial environs, tree canopies, plants and soils should be used to develop strategies, engage in project designs, monitor success/failure and develop functional and intrinsic values of trees.
Furthermore, benchmarking data as early as possible allows the next generation to improve management developing a more successful urban forest. Imagine how valuable decades of good data (if it were available) would be to us now in our decision making? It is only responsible that real measurables enabled thorough benchmarking is taken up now for following generations of city planners and urban forest managers. Successes and failures can be tracked in time to assist in making better informed decisions so that irretrievable growing and establishment time is not lost.
What does the future urban forest look like?
Thinking about the future urban forest conjures up both positive and negative images. Derived from multiple conflicting and cumulative issues, the future urban forest cannot be based on plantings of tube stock and plastic guards, monoculture advanced tree boulevards or scalloped tree canopies around power lines. This current landscape is full of compromises and convenience – and unfulfilled possibilities. The real future urban forest contains canopy everywhere. Beautifully healthy, green, dense, biodiverse, connected, habitat containing canopy in every direction. The end game of urban forestry is all about canopy and healthy trees, not individual (feel good) plantings. It’s all about one big biome.
Communities which choose to invest in urban forestry would see the value of their investment more effectively if robust scientific understanding was provided. Additionally, the engagement of a community is essential to the overall success of urban forestry and cannot exist without active involvement and ownership. A strategic approach to evaluate the scope, site requirements, regulation, installation, maintenance and cost of urban forestry will require consistent attention and work. This evaluation process is most important when substantial long term investment is made in developing the urban forest.
In optimal conditions, trees take decades to grow to maturity. In their current anthropogenic form, trees are inhibited in their health, vitality and life expectancy through poor past and present urbanisation practices and expectations. This need not be the case. The future urban forest can be a wonderful place, but there are fundamental major issues that must be addressed now.
Recent research findings show the canopy of individual trees can provide some quantifiable functional services. These can only come from dense canopied healthy trees, of which there aren’t enough in the urban landscape. Data needs to be used to monitor and understand this so actions can be taken to make it better.
The individual trees we have now can all be identified and monitored, while the in the areas where new individual trees are planted, their establishment can be better facilitated through data monitoring and subsequent growth management practices. The types of vegetation required to re-establish, protect and enhance biodiversity and healthy ecosystems can also be better understood through data accumulation and its interpretation.
The next component is the implementation of the above in practical ways. Funding of projects, community engagement, well-designed installations using multidisciplinary expertise and inputs plus leading management practices and future monitoring can all be supported through data collection.
One can only imagine a future urban forest of canopy everywhere and the possibilities this brings. But consistently, the biggest cause of urban tree decline and failure is the impact to tree health through incisions to the essential components of trees. The feeder and structural root zone, structural branches and canopy are all crucial to individual tree health. So too is the makeup, volume, health and biological function of the medium in which the tree grows. The impacts of grey infrastructure are detrimental to tree health and dense canopy cover.
Powerline infrastructure, The NBN, water and sewer, gas, footpaths, roads, and building footings all affect individual tree health and life expectancy. Data from these infrastructure examples can be overlaid and enable urban forest managers to understand the viability of tree establishment and potential future issues posed by these grey asset services, but let us not forget the importance of the green assets and the functional value they provide, and prioritise accordingly. These green assets can and will far outlive the grey assets and provide accumulated benefits as they continue to grow and connect the urban forest.
Canopy cover takes decades to form. When canopy cover provides quantifiable functional value and maximum productivity, these trees are likely to have their employment terminated due to powerline intrusion. Urban forestry needs a sound business and employment model for its botanical employees to be successful.
Even though by present definitions, the term ‘urban forest’ could be considered an oxymoron, it is essential for future human habitation in cities that this nexus is dealt with scientifically and with holistic evidence to find a way of dealing with current shortcomings and future pressures. There can be successful outcomes, but they do not happen without historic evidence and detailed consideration of the many variables impacting on and affecting the synthesised environment of the urban landscape. If trees continue to be planted without consideration of complete and complex data of the whole living organism across a suburban landscape, it will end up as a canopy looking like a road map due to the never ending confinement of canopy from grey infrastructure. Additionally, these trees are very unlikely to reach their mature size and age to provide quantifiable functional services thereby becoming earmarked for removal due to poor condition.
In future, if current research findings are heeded, the green canopy cover provided by a healthy urban forest will find its place as being incredibly valuable to urban habitation; it is nearly as important as most basic essentials such as clean water supply. The difference is that the tap cannot be turned on or off - it takes decades for individual (healthy) trees to begin to provide quantifiable benefits such as reduced urban heat island effect. With decades of investment, these natural assets could provide services that have cost the community an invaluable element – time. It is incumbent upon policy makers, designers and managers to build on that investment so the trees continue to flourish to further benefit following generations. The conventional practice of over-pruning and lopping to ‘manage’ tree health and pre-empting reduced tree life expectancy due to external factors such as drought only add to the overall demise of the urban forest.
With access to reliable long term whole-tree data, good design and planning of tree placement may well help overcome the oxymoron of the future urban forest. Much more investment is needed in complex scientific research to further develop an intricate understanding of the urban forest biome so its real potential can be realised.
All who have a stake in the matter will need to be open to ongoing collaborative efforts to enhance an already ailing urban forest. Commitment is needed now to embark on this journey and embrace the concept of passing it forward.