Resilience and climate change
I spent much of the early 90’s cycle-touring and one day I saw a very ordinary garden in downtown Anchorage, Alaska and realised for the first time that it had taken an army of people to create and care for it.
Later I visited Kew in London and was again struck by the organisation that goes into a park – these were eureka! moments for me. I thought I’d like to do ‘something’ with plants back in NZ. Since then I’ve worked in a dozen aspects of parks, farms, orchards and gardens as well as gaining degrees and much self-directed study, increasingly solving problems rooted in real sustainability and resilience, often around water.
Increasingly when things go wrong now the state sector response fails both in short-term response and longer term planning. This failing is complicated but seems to lie in siloed thinking; denial of facts; inability to scale rapidly; and falling funding. Response is usually to a very basic standard insufficient to re-start real communities.
We face many problems but clean water is a hard limit for us humans (and for non-human nature) – so basing solutions around water is sensible – it is also the core basis of landscape architecture. Water can be a social binder to protect the land and the people – it’s a way of making a real politics that doesn’t shift with time and fashion. It’s also a way of making a politics that could make the other politics irrelevant (but that’s for another time).
So starting where we are we can consciously realise that my drain flows to your drain and start solving things from there. Also realising the value of water; at least 30% of a city’s capital is tied up with water.
Streams flow from catchments and are fed by smaller and smaller streams. We could envision Dunedin as catchment neighbourhoods of 10 to 50 homes set around a stream source – even if we can’t see the stream it is there – often buried, and bursting through the surface in flood.
With climate change we are seeing rapid changes; seasons are being replaced by prolonged dry or cloudy periods, even-rainfall has become mostly drought spells interspersed with cloudbursts. We also get some seriously hot days that are hard to live with. Wild-fires too are becoming more frequent. We’re going to have to start working with this, and working together.
Starting where we are we (even if we rent) could place a 200 litre tank below a downspout (ideally you put a on\off tap in the line*) – we detain some water and use it later when it is dry and this water doesn’t leave our land. We also have an emergency supply. Everything else is just expanding on this idea. *This is not legal but relying solely on the state-sector while they endlessly debate the height of the table is not a survival strategy
We could scale this up to a soil-filled animal trough and plant a vegetable garden in it, or we could set the trough lower than the barrel and we have a rainwater treatment chain
Waterless (composting) toilets are another part of this package altho’ difficult in NZ where government is conservative and far behind the times. If you can remove stormwater and sewage from the city a council’s infrastructure falls by 50-60% and the city becomes a lot more sustainable and robust.
The next stage would involve looking at the lawn which is typically a hard, compacted monoculture – by contrast diverse lawn plant mixes have roots at different depths and can store water at multiple depths – and stay alive in droughts. By reducing lawn size by shrub planting we can dramatically increase permeability and reduce runoff. We can also plant shrubs into the lawn and mow them off; over time they change the lawn to a more porous state.
From here we may consider swales, for instance with a miniature ‘moat’ around the house, except porous and densely planted so it never fills. These can also be linked to our neighbour’s swales and to rainwater ponds at the neighbourhood scale. It is also possible for neighbours to share use of a pond. Areas treated to this level do not generally require citywide stormwater systems – this is a huge cost saving for the city and a gain for everybody.
Next up are paths, driveways and communally, the road. If you visit Larnach Castle you’ll see the parking area is gravel with grass growing in it. This is a year-round surface able to handle buses and tucks. In Europe this is a common surface for reducing water runoff. It’s also a lot cheaper than concrete or asphalt plus it is closer to carbon-neutral.
If you must have the latter there are porous versions (available in NZ) where you can pour a bucket on the road with no runoff. While this is more expensive than normal asphalt underground pipes are not normally required.
Plants need to work in these places – everything must have at least two purposes!
Evaporate water, provide food, fuel, fibre, shelter, leaves for mulch, privacy, cooling, silencing traffic noise, enhance play spaces, add value to our homes and businesses, bring delight to our lives…
Shelter from the storm … and the nor’Wester
Hedges, trees and shrubs are a big part of our stormwater solution. But not just any trees; we want species that support wildlife as well as feed us, and hopefully provide fuel, and provide shelter.
A helpful approach to land design where water may be in short supply, is to think about planting in zones, and then to chain those zones together and use gravity to move water between zones. For instance you may be running a rain barrel or directing to grey water for vegetable growing, down ‘stream’ of this there may be some summer perennials and further down some young shrubs needing support for their first couple of years.
Where over-abundance is a problem you would plant in zones but select plants for thirstiness e.g. irises, sedges, rushes to get some of this water back in the atmosphere. Another very important consideration when selecting plants is to have lots of canopies; ground-covers and grasses, then small shrubs, larger shrubs and finally trees – this way one can trap 30% or more of the rainfall before it ever gets to the ground – much immediately evaporates again, while the plants absorb some.
So what is happening from all the above actions?
We’re successively removing stormwater from the city system; infiltrating it into local soils where plants can use it and changing the local humidity where it is more friendly to us, wildlife and plants. And we’re growing stronger, more interlinked as a community in doing these things. Now when things go really wrong council can focus on structure of the city instead of in single streets. Having more money available from not having to constantly spend on water infrastructure also gives council more ability to plan.
A gentle cooling breeze on a hot day is nice, a relief from the nor’Wester (a föhn wind). The best way is to filter wind through a hedge or tree screen. Planted shelters also work better if they have rough top edges so choose small trees and pruned them minimally, say to 2.0 to 2.5 metres high. Also unlike walls you can grow hedges without a permit. Some suitable for smaller properties include:
– English beech – must be trimmed annually, else you get trees
– Pittosporum eugenoides, native, fragrant
– Chatham’s olearia, native – will grow in toughest spots to about 4metres
– Coprosma virescens, native – to about 4metres left to itself
As we’ve seen in the last few years, wild fires are becoming more common, including in the wintertime. So far this is mainly unseasonal drought, and also very wet springtimes, followed by rapid summer drying as has been happening in the Waikato this year.
Another fire issue and much less well understood is where the rapidly rising CO2 level is changing the flammability of some plants, for instance a common roadside wed – brome grass has been shown as more flammable – link USDA. Meanwhile some other species may become less flammable, e.g. some eucalypts – link Uni westernsydney.
I have seen people plant landscapes using species they assumed would not be flammable – but that later proved to be very wrong. A good starting point for NZ is our fire service’s flammable native plants list. I have an ever growing list of fire data for natives as knowledge increases, especially in light of rising atmospheric carbon.
Living walls and roofs
These are fashionable items but unless thought out really well (and with a pre-considered maintenance budget) they don’t end up being fit for purpose.
These are not really gardens at all but a hybrid between considered engineering and very high-end planting knowledge and care – they can replace a lot of infrastructure including drainage and air-conditioning.
When built and maintained well they are amazing and have huge water, biodiversity and building benefits (buildings become quieter and have more stable temperatures).
Dunedin has many old quarries, landscape depressions and former road cuttings which are shaded \ or run cooler than the surrounds. There’s also an extensive network of deep gullies, many with year-round stream flow. These are mainly at the neighbourhood scale, many are little-used – all would have value if they were seen as cool-microclimate refuges. This concept is being looked at, mainly overseas, but one has to wade through a lot of technical jargon to find things applicable to real life – a good place to start is Ecosystem greenspots – identifying potential drought, fire, and climate-change micro-refuges – this article looks at New South Wales but the principles can be generalised elsewhere.
I’d love to see people realise that we are natural – self link. That we can be part of nature, and to explore this by our actions. I’d like people to realise this and start coming together in linking small catchment-based communities, and then linking up across cities.
Some of the things we do, that we are forced to do, like driving cars everywhere, these things are not natural – for instance about 30% of our driving is due to bad urban planning, much of which is historic and goes back a century or more but this kind of thinking is still being taught and is still in wide use.
We all need to ensure our councils and government know that we expect better care of Earth, better bike paths, more parks with useful plants, cul-de-sac free towns so we can walk places. Having made many lengthy submissions to councils and government I feel the only thing that will get state-sector’s attention is direct action. Feet on the ground and Plants in the ground – anything written is too easy to dismiss.
A place to start
A good project for a community to start on would be a disused right-of-way, preferably wider ones where some planting can be carried out. Doing something together is a vital part of resilience as we get to know each other’s skills and abilities.
A few very useful, practical books
The Water-Wise Home: How to Conserve, Capture, and Reuse Water in Your Home and Landscape. Laura Allen. 2015, Storey Press.
– This is very practical from downspouts to raingardens and lobbying and highly applicable to NZ.
Planting Green Roofs and Living Walls. Nigel Dunnett and Noel Kingsbury. 2004, Timber Press
Small Green Roofs: Low-Tech Options for Greener Living. Nigel Dunnett, Dusty Gedge, John Little, and Edmund Snodgrass. 2011, Timber Press
– These two books enable you to plan, construct and plant living walls and planted roofs. There are many lower-cost approaches and a certain level of semi-guerrilla approaches too, e.g. planting abandoned structures and temporary buildings. Plant knowledge is impeccable.
Porous Pavements (Integrative Studies in Water Management & Land Development Book 5). Bruce K. Ferguson, 2005, CRC Press
– This is a serious work, the result of a decade looking at studying many porous roads, driveways and parking surfaces to find lasting systems and approaches. An essential tool to help you in your drive to make council and government roading projects more sustainable.