Our cities are losing their greenery, even as research continues to find that mature trees are crucial to cooling urban spaces, reducing air pollution, improving city-dwellers’ physical, mental and cultural health – and even potentially reducing crime rates.
Thirty percent of Auckland’s green space vanished between 1980 and 2016, along with at least 12,879 trees, while Hamilton lost 20 percent of its green area over the same timeframe. Christchurch lost about 15 percent of its urban canopy between 2016 and 2021.
Each of these cities also has a plan to increase the numbers of urban trees. Christchurch and Hamilton are aiming for 40 percent canopy cover (currently 23 percent and 15 percent respectively). Auckland’s urban forest strategy is targeting 30 percent canopy – it’s currently 18 percent and unevenly distributed around the city’s suburbs. Research by data journalist Kate Newton found that in Auckland, the leafy suburbs are aptly named. The city’s less privileged suburbs have far fewer trees.
Mangere, a suburb where PhD candidate in sociology Justine Skilling lives, sits well to become the Auckland average for leafiness with only 8 percent tree cover. Her research examined what it would take to re-green Mangere. She found that it took far more than digging holes and planting trees. Redressing the balance, found Skilling, takes the whole community.
A community-scale guide to planting
Skilling was previously involved in a project that produced the Ngaa Hau o Maangere Ngahere Planting Guide – a booklet to help communities decide what, where and how to plant native species in their neighbourhoods.
The planting guide was a collaborative endeavour that involved mana whenua hapū Te Ahiwaru and Te Aakitai Waiohua, Māori ecological specialists Uru Whakaaro, community organisation ME Family Services, Kāinga Ora, and an array of other council and community partners.
“It’s a really practical tool,” says Skilling. “Anyone should be able to pick it up and figure out what to plant in their backyard, or in their school, or marae, or church, or, you know, wherever there is land that could be planted.”
Finding spaces for trees isn’t straightforward, as Skilling discovered. Berms contain underground services; a park she investigated holds a sewer line.
Māngere also features heritage sites, such as shell middens – historic rubbish heaps that can contain important information about previous Māori occupation. “So, if you start digging and you find a whole lot of shells, then you’re going to have to call in an archaeologist to have a look,” she says.
That’s why it’s important to be aware of how an area was originally used – as the planting guide details. “You’ve got to understand the history of the land: Was it a landfill site? What’s underneath the ground? And what kind of soil do you have? Who has kaitiaki responsibilities there?”
Then there are safety issues. In Auckland parks, for instance, council regulations forbid plants and shrubs that grow above waist height in accordance with a set of urban design principles called CPTED, or Crime Prevention through Environmental Design. Keeping sight lines through parks makes them feel safer to a wider variety of people, so that park space is used more.
“There are a whole lot of considerations,” says Skilling, “when you’re planting anywhere”.
Why eco-sourcing plants is important
It’s not just a matter of finding where to put a tree – you also have to find the right tree.
Research undertaken to produce the planting guide found that the Māngere area used to have widespread pūriri forest – but that doesn’t mean the community can plant a bunch of pūriri seedlings and call it a day. Ideally those trees need to come from nearby – a practice known as eco-sourcing.
That’s because “every area has its own genetic biodiversity happening”, says Skilling, “and if you take a tree from a different ecosystem, first of all, it might not survive very well because it hasn’t developed to grow in this ecosystem.”
Eco-sourcing also ensures that plant diseases aren’t transferred to new areas and helps to preserve the unique genetic identity of plants in a particular area.
One challenge in Māngere is that there’s very few local pūriri to collect from. “That’s really tricky in an area like this,” says Skilling. “We’ve got hardly any areas of remnant bush at all.”
But there are many other plants to choose from. The planting guide recommends a host of trees, shrubs, climbing species and ground covers that can be eco-sourced from the Tāmaki Ecological District. It’s also important to scrutinise eco-sourcing claims made by nurseries, as it’s not a regulated term.
Planting initiatives can weave communities together
Re-greening an area is a community effort, found Skilling, not only in terms of identifying spots for trees, but people or organisations willing to care for them as they grow. “I think that you probably need a small team of people that can work with schools and churches and businesses and marae, whoever has land, really, to help people to put the guide into practice, and carry it forward.”
Skilling’s research found that planting initiatives can build all kinds of relationships and skills: connecting community members, increasing their knowledge, giving people hands-on experience in the environment, helping them relate to the places they’re living, and fostering local leadership.
“The work to create the planting guide just created more effectiveness and synergy in what everyone was doing,” she says. “So, we’re not all just focusing on our little projects and competing with each other for funding and resources. But we’re all working towards something bigger than us together. And that encouraged people to invest a bit more as well, because you can see that what you’re creating is bigger than just your organisation or project.”
The guide incorporates mātauranga Māori – “multi-generational knowledge of the environment” – alongside wishes of mana whenua hapū, for the future of the area. “This actually created a real sense of belonging for everybody,” says Skilling. “So even people that weren’t mana whenua, or weren’t Māori, just kind of knowing what mana whenua aspirations were for our area, and then thinking, ‘Okay, I can contribute to that in some way’.”
The te reo Māori word for ‘forest’ is ‘ngahere’, but it goes beyond that: ngahere involves the interconnections between land, water, soil, animal life, and so on. “It’s so much bigger than just tree planting.”
Trees need communities as much as communities need trees
Community-driven groups may have more stability than government agencies. Though Kāinga Ora was one of the partners in creating the planting guide, the 2023 change in government brought an abrupt redirection of priorities; now, Kāinga Ora’s landscape architect no longer has the mandate or resources to carry out the scale of planting that the agency previously advocated for.
Social housing policies change often, as Skilling learned in her previous career as a social worker. “Some governments have discouraged people from planting anything in the garden because they don’t want people to feel too attached to that piece of land. It’s supposed to be seen as a temporary solution to their housing needs,” she says. “So it just depends on the kind of philosophy of the government that’s in power at the time.”
Now, Skilling has support from Auckland Council’s Climate Resilience Fund to work with the community to co-create an implementation plan for the guide – fostering more tree cover and stronger community relationships in parallel.
The world is facing unprecedented environmental challenges. Planetary Solutions, an initiative of the Sustainability Hub at Waipapa Taumata Rau, University of Auckland, and Newsroom, explores these issues – and the practical ways we can all be part of the solution.
