Auckland is a very leafy city. The trees that our forebears planted have slowly grown to maturity, resulting in many streets and suburbs with an attractive amount of greenery.
The city’s street trees are especially valuable… where they have been allowed to survive traffic engineering standards. For instance, there’s an immense difference in the look and feel of different parts of Symonds St. Areas around the university, with abundant, mature trees, feel much better than the concrete channel near the Wakefield St intersection.
But will development of taller buildings in residential neighbourhoods – three-storey townhouses and midrise apartments – erode Auckland’s leafiness? Will the buildings slowly grow above the trees, resulting in a landscape of roofs rather than a landscape of trees?
Evidence from other cities suggests that the answer is no. For example, Stu Donovan tells me that in Amsterdam street trees still rise above the midrise apartment blocks, creating leafy vistas.
To understand what might happen in Auckland as the city grows up, I’ve taken a look at the height of common street trees in New Zealand cities. Unfortunately, data on street trees in Auckland wasn’t easy to come by, but a PhD thesis by Fredericke Behrens provides some data on the abundance of different types of street trees in Christchurch. (“Selecting public street and park trees for urban environments“, Lincoln University, 2011)
Here’s a list of the ten most abundant street trees in Christchurch (Table 5-2 in the thesis), along with approximate mature heights (generally sourced from Wikipedia). Eight of the ten species have mature heights in the range of 15 metres or more, while three can grow up to 25 metres.
These species will generally be of a similar height as mid-rise apartment blocks, which may be in the range of 4-7 storeys high. Silver birches or ribbonwoods on the street can be attractive complements to medium-density development.
|Species name||Origin||Mature height||Equivalent to:|
|Betula pendula (silver birch)||Exotic||15-25m||4-7 storeys|
|Quercus palustris (pin oak)||Exotic||18-22m||around 6 storeys|
|Fraxinus ornus (manna ash)||Exotic||15-25m||4-7 storeys|
|Plagianthus regius (ribbonwood)||Native||up to 17m||around 5 storeys|
|Cordyline australis (cabbage tree)||Native||up to 20m||6 storeys|
|Liquidambar styraciflua (sweetgum)||Exotic||15-21m||5-6 storeys|
|Prunus cerasifera ‘Nigra’ (black cherry plum)||Exotic||6-15m||2-4 storeys|
|Sophora tetraptera (kowhai)||Native||up to 15m||4 storeys|
|Quercus robur (English oak)||Exotic||15-25m||4-7 storeys|
|Prunus x Kanzan (Japanese cherry)||Exotic||8-12m||2-3 storeys|
Furthermore, this list doesn’t include several less common species that play an important role in Auckland’s landscape, such as the London Plane tree, which usually grows to 20-30m (6-8 storeys) or even higher in exceptional circumstances:
Or the city’s many Norfolk Pines, which often stand out at a distance due to their conical shape and mature height of 50-65m:
Or the spreading pohutukawa, which can grow up to 25m (7 storeys):
In other words, it seems like we shouldn’t fear for Auckland’s leafiness: We can develop a lot more without eclipsing our trees. But that being said, I would argue that we need to do other things to preserve and improve our streets as we develop… such as planting more street trees.
What do you think about street trees in Auckland?