Mature trees are essential for good cities to live in – housing densification plans must ensure their survival | Marguerite Stanley
The New Zealand Parliament is set to take third reading of an amending bill known as the “Housing Intensification Act”. Its aim is to relax the Resource Management Act (RMA), which currently limits the height and intensity of construction in cities, in order to meet the urgent demand for housing and address affordability.
While it is clear that housing affordability must be addressed to meet the needs of low-income youth and New Zealanders, there are pitfalls to the speed at which legislation is rushing through the system. Yes, we need more houses and we need to step up our efforts in our cities so that we do not have additional impact on the rural landscape as the tentacles of our cities spread into key food production and development areas. natural ecosystem.
However, we also need our cities to be built and enlarged in a way that takes advantage of the benefits that urban greening offers to infrastructure – e.g. better water quality and reduced flood risk, energy costs. , noise and air pollution – and the health and well-being of their inhabitants. Studies have shown that blood pressure, respiratory illnesses, depression, and anxiety are lower in more natural neighborhoods. Maximizing the benefits requires very intentional planning.
Previous changes to the RMA removed general protection of urban trees, which meant that permission was no longer required to remove trees on private land unless that tree was specifically protected (e.g., on the list of remarkable trees). This meant that only around 15% of the trees on Auckland’s private land were protected, which is disastrous given that these trees make up 63% of urban forest. While it is difficult to determine the extent of tree loss across the country since this 2012 amendment, we do know that some Auckland suburbs lost 35% of their urban forest between 2006 and 2016.
Given the well-defined and significant social, cultural, economic and environmental benefits of trees in cities, the impacts of another amendment that allows additional removal of vegetation to increase physical infrastructure are likely to be substantial and long-term. term. The “death by a thousand cuts” that is occurring in New Zealand cities from the cutting down of trees during the escalation cannot be reversed. It is not enough to simply compensate for felled trees during landscaping by planting seedlings in public spaces. The benefits of a single large tree – from sequestering carbon to improving biodiversity – cannot be replaced by minimalist landscaping, mown lawns or even planting seedlings that can take 50 to 100 years. to provide these same benefits.
The Covid-19 closures demonstrated the importance of having nature in our neighborhoods and highlighted the inequalities in access to green spaces in our cities. Given the clear evidence of the mental and physical health benefits that nature and trees provide to people, reducing urban forest and even exacerbating these inequalities in health and well-being seems like a startling faux pas.
We can intensify and increase our building stock while putting in place protections, even improvements, for our urban forests. These urban greening strategies can ensure that the people who live in these homes will experience the health and well-being benefits of trees, making developments more livable.
One guideline that has been proposed internationally is the 3:30: 300 rule; three trees should be visible from each house, each neighborhood should have 30% forest cover, and each house should not be more than 300m from the nearest green space. This proposal promotes the idea of “access for all residents” and helps alleviate the remaining inequalities with the overall city canopy goals. It also forces developers and planners to consider the environment outside of the site itself.
At this time, the proposed new changes do not clarify the landscaping provisions. It is possible to design developments that keep some existing large trees in place, and the benefits to residents and the city itself – although difficult to quantify in economic terms – clearly outweigh the additional costs incurred. Trees can be integrated even in small sites, if one sticks to the “right tree in the right place” strategy.
Many of our cities are focused on removing invasive predators, such as rats, to bring back our native birds as part of the government’s “Predator Free 2050” strategy; but birds need good structure and diversity of vegetation, not minimalist landscaping. So should we include minimum landscaping requirements in the amendment to the bill? Absoutely. We also need to be specific about the type of landscaping required – compared to trees, mowed lawns contribute very little to biodiversity and ecosystem services, such as air pollution mitigation.
Specifying how much of each site is under a canopy would retain the greatest benefits for locals, birds, and the city. Adopting the ‘urban green factor’, used in several European cities, would guide developers as to the relative value of different plants (for example, unmown native tufts are better than mown lawns) and promote the use of grass. green roofs and green walls.
There are several options for landscaping arrangements that require careful discussion and new collaborative relationships to ensure that urban greening is an integral part of a person’s right to a healthy home. Beyond that, cities must look to the future, plan for equity in urban greening and develop green corridors that allow wildlife to thrive throughout the city. Only then will our cities be truly livable.