Planting for bush restoration and erosion prevention

Why I'm a native plant hypocrite

March 2025

Before I choose native plants for the garden, I need to start at the very beginning. Before there were houses here, there was bush. The type of bush that was here, and is still here in slivers of reserve, matters. Or it matters if I want to help along the local ecosystem to support native wildlife. The associated plants will also be the easiest things to grow because they are completely appropriate for the site.

Auckland Council has catalogued all the ecosystems in its area - 36 of them - and published a guide that says what the bush used to be like, the wildlife it supports and what could be expected now for each ecosystem. On Geomaps, I can look up my address, put on the environment layer and see the current and potential extent of ecosystems locally. It shows that the bush across the local gardens is unclassified, but the reserve it connects into, Muriel Fisher, is "WF12" with pockets of "WF9". On the local defence land and at Kauri Point Centennial Park, along with a recovering ecosystem, "VS2", is "WF11" and that is also the ecosystem that the Council would expect over our property.

Part of a page from the Auckland Council ecosystem guide

Currently our bush is also a recovering ecosystem and if I look at the guide, it looks like the same as the defence land - kanuka scrub. It lists associate plants as tall mingimingi, prickly mingimingi, Coprosma rhamnoides and tauhinu, as well as māhoe, five-finger, hangehange, lancewood, kōwhai, karamū and putaputawētā. This gives me a really good idea at what could be in the garden, given its missing understorey. Indeed, the garden already has a lot of those species in it - which I catalogued when I undertook a bioblitz. I now have a better understanding of what I can add to fill the gaps.

The flowers of the kowhai in the garden

The idea is that this recovering ecosystem will eventually mature, allowing the long-term forest trees to take over. If I look at the guide, WF11 is kauri, podocarp, broadleaved forest. WF12 is similar with hard beech included as well. WF11 has a wide range of plants associated with it, depending on the geography of the area, but the broadleaved trees in gullies include taraire, tawa, kohekohe, pūriri, northern rātā, pukatea and rewarewa. Kauri and others are found on ridges and hillsides. This gives me further information about what would be appropriate trees to add. The garden already has pūriri trees and kauri, but none of the rest.

Another way to see what would be appropriate for the bush area of the garden is to visit the local reserves. I went through Kauri Point Domain, Chatswood Reserve, Kauri Point Centennial Park and Smiths Bush, taking note of what was growing. Smiths Bush is a different ecosystem and further away, but it was very clear from walking round there that the bush consists of different height levels and there will always be climbers sprouting alongside shrubs and tree saplings. My bush has no climbers at all, unless you count moth plant. In my old reserve a lot of kaihua, New Zealand jasmine, would grow so this is definitely an element to add. Kauri Point Centennial Park, a short walk away, was the most eye-opening and just chock full of different native species. I may blog about it separately because it was lovely to walk there.

Two last factors that contradict all I've said so far: Firstly, whilst I want the bush area of the garden to be as true as possible to the original ecosystem, this garden already has a lot of trees planted that are more associated with other ecosystems, like the lacebark, tītoki and ribbonwoods. After all, it is a garden and gardeners do like mixing interesting plants together. I don't want to throw away plants, especially as the lacebark is a wonderful tree for lepidoptera. Also, to maximise year round nectar and food plants for butterflies, bees and birds, I want to put in native plants that help deliver that. They may not be closely associated with the specific WF11 or VS2 ecosystems, although they will all be appropriate for Auckland.

Secondly, I have to plant for erosion control as well. This is where the project plan fails - it didn't really mention erosion. However, it is the threat of soil erosion that has put the pressure on trying to create a butterfly garden AND plant up the bush in the same year. There are signs of previous slips in the garden and all across the garden there is bare earth, which is just asking for trouble. In heavy rain there is a lot of surface water heading down into the stream.

Certain native plants are known for erosion control. I've got information from a number of sources as I've had to research this because I haven't had to deal with slopes much before. I think the tītoki and cabbage trees in the garden have been planted previously for this reason, plus are elegant. What's good is that many plants do double duty, so muehlenbeckia complexa, which is a beach plant, is a host plant for copper butterflies, shelter for birds and insects and also provides berries for geckos and birds, on top of stabilising the ground. Hebes are also known for ground stabilisation and I am all for plants that have beautiful flowers and will attract butterflies. There's a great list of erosion plants here and a longer list here.

I have been playing with a native plant list for some time, but I really got down to it in February, taking photos of all the areas of the bush that needed planting up and making a list of potential plants as I went. Then I had to cull it for cost. Even with wholesale prices, big quantities of plants are expensive. I'll have to buy another batch later.

Bare earth on a slope below the boardwalk

Kaipātiki Project is a locally run charity that, among other sustainability initiatives, grows native plants for restoration work. Because they are growing from locally collected seed, they are the most appropriate source of my plants, but I will be limited to their current stock. There are other things, such a mingimingi, I want to add, but I''ll need to find a different supplier or see if I can grow them from seed from the wild.

So what am I ordering?

• Three different types of grasses for the stream side and water channels, carex secta, carex dissita and carex geminata. I've already got some carex virgata, which I picked up in a plant sale. Some do better in more sun and some can take dry conditions. The stream needs more attention than I can give it this year, but holding the soil together and trying to slow down the water movement through planting is a start.

• Rengarenga lilies - flowers that will take various light levels

• Three types of native climber: NZ clematis, NZ jasmine and NZ passionfruit. I'll use the passionfruit as a trial alternative cover plant to the boston ivy that has taken over everywhere, beautiful as it is.

• Native dianella, tūrutu - for the transition native flower beds

• Two local types of hebe - koromiko and veronica macrocarpa - for the native flower beds and for erosion, as well as flowers, flowers and more flowers

• Flax - for erosion, for the flowers and for shelter

• Two types of trees - a puriri for closer to the house, as the current ones attract lots of birds, but are hidden at the top of the garden, and two rewarewa, again for the nectar source for birds and lizards and to fill spaces where the invasive trees were

• Libertia peregrinans - for the flower garden

• Pratia angulata - just one to start with, for the slope down to the stream. Is also known to attract admiral butterflies, but this one will probably be in too much shade to be a food source

• Bachelors button, Leptinella dioica, for the native flower bed

• Coprosmas - coprosma areolata, coprosma spathulata and coprosma rhamnoides - these provide berries for lizards and birds and will help create an understorey in the bush

• Kanono - there are quite a few in the garden already, but I wanted to put one on the slope down to the stream to help create an understorey under the trees

• Kawakawa - these are great understorey plants for shade and the fruit is edible for us, although the birds will probably get there first

The other plants I want to use:

• Mountain flax - for the garden, not the bush. Flowers for the birds, but a smaller plant.

• Kōtukutuku, tree fuchsia - for the stream side, great nectar source for birds, great for erosion, beautiful bark. Possums have eaten these out of the area, but they do occur naturally and can be found in Eskdale Reserve.

• Parataniwha - this is a beautiful, local streamside plant for the shade. The stream sides are particularly bare and amongst the steepest parts of the garden

• Taupata - great erosion control and berries for lizards and birds

• Muehlenbeckia astonii - for a hedge

• Seven finger - berries for the birds

• Kohekohe - a winter flowering tree for nectar

• Mingimingi - This is definitely a local understorey plant and it looks like it would provide shelter for wildlife

• Akepiro, a type of daisybush - a shrub with beautiful white flowers and can take the coastal wind

• Rangiora - another local understorey plant

• Native broom

• Coprosma umbrellata - this has been planted in a local reserve, perhaps incorrectly, but is winter flowering and was buzzing with bees

It's quite a list, but the idea is to widen the biodiversity in the bush, giving more food sources at different times of year. It'll be worth all the planting to see more wildlife using the garden for food and shelter.