Green space as vital urban infrastructure — LANDSCAPE ARCHITECTURE AOTEAROA

A NZILA Climate Action Group spokesperson has welcomed a report from the Parliamentary Commissioner for the Environment which states green space should be seen as vital urban infrastructure in Aotearoa.

The report by commissioner Simon Upton entitled Are we building harder, hotter cities? The vital importance of urban green spaces warns planners and authorities “must not lose sight of the environmental benefits that urban green space provides.”

This image, captured with an infrared camera, reveals the surface (not air) temperature on a sunny summer afternoon in January on a treelined street in central Wellington. The yellow areas are hotter surfaces, and the blue/black areas are cooler. The air temperature was 23 °C. The surface temperatures at two locations are shown at the top left of the image. The pavement in full sun is 47.7 °C whereas the ground under the tree is 20.3 °C. Image credit - PCE Report March 2023.

“Planning for and providing urban green spaces of any description, public and private, should not be optional,” the commissioner says.

He says New Zealand cities are currently well-endowed with green space, but adds some suburbs are greener than others.

“Our data show that urban green space has been declining over time. Between 1980 and 2016, green space per person fell by at least 30% in Auckland, and at least 20% in Hamilton. Nearly all of this loss occurred on private residential land.”

The report reveals two main trends are responsible for this reduction. The first is infill housing developments and the second is newer subdivisions which see bigger houses on smaller plots of land being built.

The commissioner believes this “creates a conundrum for councils, how can they simultaneously intensify while increasing provisions for green space? There is a need to compensate for losses on residential land, if the trend is to be reversed.”

NZILA’s Craig Pocock, who is also a Beca Principal and creator of the Carbon Landscape concept, advocates for the importance of not just developing green spaces, but also developing in a way that preserves existing green space values and features.

“It's the landscape and environmental character that we risk negatively impacting when we cut down mature trees, to make space for infill housing, those trees cannot be replaced to an equivalent scale for decades.”

The report finds Greater Wellington is the exception with the proportion of urban green space remaining as the city has grown. “Almost two thirds of the urban area is green space, and that figure increases if the outer green belt is included.”

But green space is not necessarily public space, says Craig, who notes the intensification of single-dwelling plots will lead to reductions in visible and permeable green space on residential land. He believes this will impact visual character, but crucially will also affect a catchment’s ability to absorb surface water in weather events.

Craig’s concerns about the capital largely stem from infill housing in its suburbs competing with narrow roads and topography, creating challenging conditions to maintain green space at current levels.

“Wellington’s topography creates a landscape of steep slopes and narrows road, the residential front yard spaces are often were the mature trees and vegetation is established which contributes to Wellington’s green rolling image. However the residential front yard and associated mature trees are going to come under pressure with increased density with the likely outcome of a less green environment.

“Our observations of medium density built in Wellington in the past three decades did not allow the space to replace trees and vegetation in a like for like fashion. The final result is less green environment for people to look it, walk pass and generally enjoy”

This exemplifies the balancing act that authorities will need to consider, as redevelopment of residential areas will take place on a granular level. And this, says Craig, is where the Parliamentary Commissioner report comes in; “the difficult part will be implementing the details and how they apply to each local authority.”

He believes though that reports like this are hugely important “because it sends a clear message that actually we've got to watch this space and that it is important to balance up growth with opens space and landscape values.”

This issue is one that blurs the line between national strategy at a central government level, and how such a strategy will be implemented by the numerous local government bodies existing in Aotearoa. As recent weather events have shown, large cities and rural communities alike will be directly affected by how any strategy plays out over time.