Bridging Waters, 22 February 2018
This is the first Bridging Waters event for 2018.
The full series can be found here, along with past events.
The Importance of Trees in Liveable Cities
Clare Burgess, Resilient Landscaping Forum
Henk Egberink, Treekeepers
A short talk on the economic and social benefits of trees to a city and the commitments countries and cities have made at the Paris Climate Accord of 2015 on increasing their tree canopies.
Clare and Henk's combined presentation (pdf, 4.5MB)
Johann van Biljon, Green Intaba
Bringing the fynbos into our gardens. Intaba exists to make conservation practical to all people. We love to partner with our clients to create beautiful, indigenous gardens which mimic nature and to restore degraded land to functioning ecosystems.
Take home messages
- Trees are good. Look after the ones we have, especially during the drought. Make a plan to plant and maintain more once the drought is over.
- While it is good to consider local indigenous plants as a first step, it may be more appropriate to consider plants that fit the climate, for the Cape plants from other Mediterranean climate trees which are proven to work in winter rainfall, summer drought conditions may be more appropriate.
- The urban environment in Cape Town cannot mimic the natural systems that require fire regeneration processes which are essential to local endemics. Going back to endemic won’t necessarily work. Create section of local plants along what is more suitable to the impacted urban environment. There are very few endemic trees suitable for planting in the city. Planting shrubs and ground covers is an alternative to planting trees but they do not create the same ecological functions as trees or the have the same environmental values. Some indigenous plants, mainly from Eastern Cape, where there is all year round rainfall can adapt to local conditions and are suitable for use.
- Healthy soils are very important. We need to get more biomass and organic material into our soils. At the same time, trees improve the soils. It’s a virtuous cycle.
- ‘Alien’ is contextual. To be listed as alien does not necessarily mean to remove. It means to manage it properly. Move from a mindset of threat to management, in the context of the NEMBA regulations and categories of plants.
- The city is an artificial, managed environment – not a natural system, and so different regulations should apply. Our difficulty in Cape Town is that we have very important biodiversity on our doorstep and so we need to find win-win solutions for both systems.
- Consider the bigger picture: Trees, rivers and cities are managed systems with limited resources and political will often leading to poor decision making and bad management.
- Start a movement to look after trees. Urban trees are the ‘street kids’ of the urban forest. We have a forestry act, but we do not have enough resources to protect the trees.
- Important cities in the world recognizes the value of trees. Cape Town needs a good tree plan and policy. Start by counting our trees and surveying them in an inventory which can be used to manage the risk. This is important. Risk management is what everyone needs to know about in order to make decisions.
- Manage the urban forest better. We are still importing braaiwood from places like Namibia. Locally sourced firewood can contribute to the removal of the alien invasive trees that affect the catchment’s water availability, and we can manage our urban forests as valuable assets and as productive landscapes.
Also see the media release rom the resilient landscaping workshop.
One would think a conversation about trees in cities would be straightforward. More trees are better, of course. But the devil is in the details: Should these trees always be indigenous? Are trees better than fynbos? What about fruit trees?
Clare Burgess and Henk Egberink gave passionate presentations about the importance of trees in general. An interesting point was that indigenous trees – at least in the Western Cape context – are often evergreen, and in the city one would prefer deciduous trees to allow shading in summer, but more sun to enter living areas in winter. In the general conversation the point was raised that Cape Town is naturally a very nutrient poor environment, that does not naturally support an abundance of growth. The reason for the fynbos biome and large range of biodiversity is because most fast growers cannot survive here. Aiming to grow food here is difficult. Planting food trees require nutrition and irrigation until the tree is established – in other words, a high amount of care and maintenance.
Clare further cautions against the term 'alien' - rather promote the correct use of the term ‘alien invasive species’ which are a threat to local bio-diversity. Many of Cape Town’s trees are ‘exotics’ in that they were imported from elsewhere and are now established in their environments and pose no threat to existing bio-diversity. Legally there are alien invasive species and these are a threat, but the use of the term alien is extremely xenophobic and has led to many examples of people removing plants and trees (and people) incorrectly and without due process just because they are not local or because they are a nuisance. This is one of the issues that TreeKeepers is trying to address and change the mind-set of the public.
Henk provided compelling arguments to conserve older trees – they require less water and can capture more carbon dioxide. But it takes a long time for trees to mature, so we need to work harder at conserving our established trees, a big ask in the current climate of property development and densification. The Paris Climate Accord is committed to increasing forest cover substantially.
Johann van Biljon argued for using our urban landscapes to restore the original vegetation. His presentation provided a spirited discussion, raising questions about how to integrate the urban into the wider environment. One agreed approach is to make sure to create small pockets of endemic species alongside new, other developments. How does ‘appropriate’ vegetation provide the tree cover that we need within urban areas? How do we get local, endemic waterwise trees into the urban environment? This led to a conversation about what contexts favour trees – the shade in the southern side of mountains, for example, that could be mimicked by the south sides of houses.
Modified environments within urban areas lend towards different approaches. Planting for water sensitive design is extremely important, for example shaping the landscape to create swales that can allow more water infiltration and storage may improve the survival of the trees in a lower maintenance way. Trying to go back to endemic alone is not adequate for us as the main species. Clare used the example of planting palms in a project with a busy road and explained that palms are robust plants that can withstand the high amounts of stress – including vandalism – that the urban environment imposes.
The Greenpop programme has had to be retrofitted to deal with the lack of water and to improve the survival rate of the planted trees generally. Fynbos and trees need more water than 550mm per year – new trees will not survive without proper irrigation. It is important to include ongoing care of trees in urban areas.
While fruit trees as street trees sounds like a great, equitable solution, they are high maintenance and prone to disease. They need adequate management. Olives are good. Fig trees, avo, noemnoem, kei apple, grenadilla is good. Generally it is better to keep fruit trees inside property boundaries where the responsibility of maintenance is clear.
The concept of ‘sustainability’ was a source of general frustration from both the audience and presenters as it was felt to have too many loopholes that negates the good intentions behind the concept. It needs to be redefined to use resilience more, including adaptive environmental management principles.
Overall, the participants and the audience agreed that we need a new way of gardening; design must change; maintenance needs to be context-based. But this does not mean ugly gardens. We should aim for gardens, and urban environments that are 1) water sensitive, 2) contribute to urban reforestation, 3) contribute to conservation and, 4) yes, also to win awards, to be beautiful!