Navigating by a new Star

Taking the measure of a garden.

A pre-pilot study for an innovative New Zealand garden rating system is hoping for a bright, biodiverse future helping homeowners and nature lovers alike.

Over the last six months the launch of an exciting new conservation initiative has seen researchers at the University of Otago walking into the backyards of 78 homes to check out and mark down what’s growing where.

Based in Dunedin, Queenstown and Arrowtown, the study assessed residential gardens against key criteria for biodiversity. The goal is to eventually roll out a nationwide rating system, the Gardenstar, which would be similar to other property certification formats.

It’s an exciting prospect for many homeowners who have worked over the years to grow and support local flora and fauna. In the future it’s hoped the new rating system will both recognise these efforts while positively affecting the perceived value of a property.

Prof. Yolanda van Heezik, regarded as one of our most prominent urban ecologists, helped lead this first stage of the study. It’s hoped that her inspiration for the initiative will eventually lead to major changes for how private gardens are seen as valuable resources for the country. As an important proportion of green space in New Zealand these gardens have a significant part to play in helping grow and protect our future.

Here’s the first part of our interview about the start of the study and how it was undertaken. Be sure to check next month for the second part!

What is your background?

I’m an urban ecologist and so much of my research has focused on urban gardens. More than 85% of NZ’s population lives in urban areas and most of their interactions with nature occur in these areas.

Although urban landscapes are highly modified they can still support significant biodiversity. This biodiversity is important because it supports ecosystem functioning and also provides wellbeing benefits for people.

How big a space are we talking about with urban gardens?

While green spaces such as parks and reserves are where the greatest biodiversity is found, private gardens cumulatively make up the largest area of urban green space. In Dunedin they cover 36% of the area of the city!

“If owners could be persuaded to view their gardens as places where other species could live, small changes in many individual spaces could make a big difference across a city.”

These spaces are all owned by different people with different ideas about what makes a garden nice – and they vary hugely not only in size but in the extent to which they support biodiversity. If owners could be persuaded to view their gardens as places where other species could live, small changes in many individual spaces could make a big difference across a city.

What ‘planted the seed’ for the Garden Star initiative?

The concept was born out of a chance meeting at an Urban Futures conference in early 2020. I was talking with a manager working with Kainga Ora and she was concerned that their housing programme had no guidance around protection of existing garden biodiversity – or guidelines for creating biodiverse environments.

She told me about the Home Star programme, which is a national accreditation for sustainable homes hosted by the Green Building Council. That conversation led to the idea of a Gardenstar accreditation.

Professor Phil Seddon and I posed the concept to the Endangered Species Foundation and they enthusiastically took the project on to explore development of it.

How did the pilot study progress from there?

Last year Phil and I assembled a team of about 20 experts, our TAG (Technical Advisory Group). They are biodiversity experts from several universities, Manaaki Whenua Landcare Research, Pant & Food, city councils, regional councils, private consultancies and landscape gardeners.

Working with the TAG we came up with a list of garden features that were indicative of biodiversity. Phil and I then created a survey designed to capture all the information not just about a garden but also about the way it was managed.

What are the key things you are looking for in a garden?

We developed five key categories: habitat extent, habitat quality, habitat management and garden context. Incidentally, ‘sustainability’, while obviously important, is not a major focus of the study. That’s because certain sustainability features are not always consistent with native biodiversity. However we do intend to develop a rating that recognises homeowners’ efforts to improve sustainability.

With the TAG we applied an analysis that determines how much weighting we should apply to each of the four categories when calculating a score; e.g. is habitat quality worth more points than habitat management?

Once you had the criteria, how did you go about testing it?

During this last summer we carried out what we call a pre-pilot study in two regions – one in Dunedin and one in Queenstown and Arrowtown.

Across the two areas 78 gardens and 5 school grounds were evaluated  (as we’d like to extend the scheme to schools as well). The aim was to test how well the survey worked and how feasible it was to collect the information in a couple of hours. It also gave us some valuable data with which to calculate garden scores and assess how to translate those scores into a star rating. 

Was there anything in this pre-pilot study that stood out?

The survey identified issues that would need to be carefully considered in a subsequent study. There’s a lot to take into account here beyond the initial categories.

For example, we’re now gauging how to ensure people who have small properties are not disadvantaged. Other considerations include things like whether people should gain extra points if theirs is the only biodiverse garden in a neighbourhood completely lacking in native biodiversity. And just how difficult should it be to get a high star rating? There are a lot of issues that need to be considered to ensure the most accurate and trusted final rating.

Pictured below: The dream biodiversity team of Yolanda van Heezik and Phil Seddon in their garden.