Be a bit messy. Leave the tree foliage where it falls. Don’t mow your lawns this weekend. Sit outside with a beer and watch the birds instead. 

Auckland’s gardeners are being urged to stop being such tidy Kiwis, obsessed with putting plants behind impermeable borders and raking up leaves. The message comes from a woman who’s only trying to help you to help nature to help you. 

Dr Margaret Stanley (she actually did say, “sit outside with a beer and watch the birds”) studies the effects of human impacts on ecosystems. What she sees happening in Auckland at the moment could be depressing to such a researcher – especially in the wake of what she calls “The Great Chainsaw Massacre” – where residents appear to be taking full advantage of the lifting of Resource Management Act tree protection provisions in 2012 and are chopping down every specimen that has ever annoyed them. It’s not clear what proportion of mature trees the city lost so far – previous councils didn’t all keep track of what was growing – but it is substantial. Her research students looked at 26 sites around the city and found more than half had trees chopped out.  

Some people, she says, just don’t value trees. “They don’t want them getting into pipes, ripping up footpaths, shading them. They think trees are for the country.” 

There are others who would rather throw bread to the birds instead of grow trees for nectar-loving natives. Stanley says that just encourages sparrows and doves. New Zealand natives live on insects and sugar, not bread. She says the best thing to provide for our birds is water in a bird bath. 

Mayor Phil Goff has promised to get a million trees planted in Auckland, but “they are small, and it will be a long time before those trees become useful for the city”, says Stanley. A tree doesn’t live up to its ecological promises until it hits about 15 metres. Stanley says 60 percent of urban forest is on private land, and half our urban trees have no protection at all.

Another development that could be depressing for the tree lover, but could also provide opportunity, is the intensification of Auckland. 

“One of the issues is selling biodiversity in cities where it’s all ‘we need more houses, we need more houses!'” Stanley says some developers of large projects don’t have an eye on what will work for the future, and they plant what looks good now. “The big thing at the moment is trying to make people feel they’re in sub-tropical Queensland so they’re putting in palms,” she says. “Palms! A lot of them are getting quite weedy and they will spread further south and become invasive. People are obsessed with having subtropical gardens and it’s creating a weed invasion debt. Get rid of them now and replace them!” She’s looking at you, Millwater. 

“It’s quite intuitive – look at how returned soldiers were treated for shell shock on their return from war – they were taken for walks in the garden. There’s research showing if you can see trees from your hospital window you are much more likely to get better.”

It feels like a repeat of the 1970s trend of planting Australian bottle brush everywhere, she says. “Who would plant bottle brush when you could put in New Zealand rewarewa?” 

The Stonefields development, in spite of its vast landscape in three shades of beige, is doing some things right. The streets include swales – a gravel ditch in the middle of the road which is planted. It catches road runoff, holding the metals and stopping the water from hitting stormwater systems. This is what Stanley is getting at when she urges developers to think outside the square a bit when it comes to mixed-use space. 

She would like to see trees planted on every spare strip of land, replacing the neatly-mowed grass verges where carefully planted specimens are ringed in protective concrete. 

“We should be trying to sneak in more biodiversity – in lay-bys, playgrounds, the edges of sports fields, on golf courses and around railway lines,” she says. “We do have biodiversity in Auckland: we have something to protect already. We don’t have to have green spaces OR houses.” 

Hard figures laying out the benefits of a greener city to justify official efforts in that direction have been elusive however. In the past trees were planted on instinct. “It’s quite intuitive – look at how returned soldiers were treated for shell shock on their return from war – they were taken for walks in the garden. There’s research showing if you can see trees from your hospital window you are much more likely to get better. In the UK doctors have analysed street addresses of patients to work out that if you live in a street with trees you are less likely to be prescribed anti-depressants.

“In Australia it’s about shade so there are targets for the planting of trees because they have a direct benefit in stopping deaths.” 

In Chicago some trees are labelled with explanations of what they’re worth to the environment, the amount having been calculated. In Portland, Oregon, residents with large trees on their properties get “treebates” – discounts on their water rates, since those trees reduce the amount of water hitting drains. 

Stanley says in Auckland we should be looking at flood mitigation as justification for the protection of the trees we still have left. She gives an example of the New Lynn flooding earlier this year, where a sinkhole opened up in the town’s centre. “Trees wouldn’t have stopped the floods but they would have reduced the magnitude of the damage,” she says. “With vegetation in place the water has somewhere to go.”

“Where it’s deemed safe enough to do it, trees should be chopped up and left where they fell.”

“Maybe that’s the hook,” she says, referring to the challenges of getting people to accept trees in the city when the biggest item on its agenda is getting more houses built. “Our green spaces will reduce flooding.”

There are other reasons to encourage trees other than soaking up stormwater runoff – reduced air pollution, improved mental health and physical wellbeing – a raft of studies have made those connections but it’s hard to put a monetary value on such things when arguing with city planners. More actual evidence is needed in the form of research, and that is being done. A recent Queensland University study for example has linked a half hour walk in a natural environment with lower blood pressure and other health benefits, and was able to put a price on those benefits. 

Stanley wants planners to start looking at the big picture when making decisions for the city – from major housing projects to not just approving plant-free playgrounds because they have minimal maintenance requirements. 

But she says the council is up against those tidy Kiwis when it comes to issues such as leaving messy berms for the pollinators and insects. 

Sometimes it tries to put good practices into action and has to pull up because of public complaints. As an example Stanley cites tree felling. 

“Fallen coarse wood debris still provides perches for birds; slow release fertiliser as it decomposes; and food for insects and fungi. Where it’s deemed safe enough to do it, trees should be chopped up and left where they fell. But the public will often complain about that happening.

“Auckland Council is just responding to what the public want,” she says.

The council doesn’t have to take ecological values into account in every decision it makes, but it does have to think about impacts on Māori. Stanley says mana whenua have an opportunity to help here. “They are very much tied to the land and value the environment,” she says. “Often the outcomes they are looking for are environmental outcomes as well.”

Stanley says one of the best examples of urban regeneration in Auckland is with what Ngāti Whātua Ōrākei is doing at Bastion Point  – where efforts are being made to restore the mauri to Okahu Bay. Replanting is being done with an eye to kai – cleaning the streams to get eels back in them – medicine, and weaving materials.  

“Their ecological restoration project is fabulous, inspirational,” she says. “They are really trying to integrate the reserve and people. That’s about as urban as it gets – you can look out and Sky Tower is just there – they are really talking about people and biodiversity together.”

Dr Margaret Stanley holds the last of four lectures in this year’s University of Auckland Vice-Chancellor’s Lecture Series entitled Life in the Big City: human and environmental health in the face of urban intensification. Her lecture, Wild Auckland: How liveable is the city for nature and people? is on September 13 between 12 -1 pm at the Business School’s Owen G Glenn Building. 

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