Dutch evolutionary biologist Menno Schilthuizen, a professor at Leiden University and author of the 2018 book Darwin Comes to Town, says the best interventions make use of those species that are already succeeding in adapting to urban environments. “We should create spaces for them to settle and colonize naturally, rather than ‘create’ ecosystems and plant them as complete mixtures,” he says. This may mean eschewing much-promoted ideas such as “green walls” that often require irrigation, in favour of materials such as the “living concrete” being piloted by University College London’s Bartlett School of Architecture. This is designed to be bio-receptive, an “architectural tree bark” that can be easily colonized by airborne algae, moss and lichen spores. Schilthuizen says: “Buildings can be built from novel materials that allow insects and small plants to settle without compromising the structure and function of that building.”
This new form does not suit everyone’s idea of what nature in cities should be. In many parts of the world, the use of non-native species, often in Western-influenced formal gardens with lawns, carries connotations of power and status. SLA’s Astrup has experienced this with a commission in the Middle East, where the strong desire was for non-native plantings that would have required a huge amount of irrigation to sustain. “If you don’t work with native species, then you can’t reduce heat in a sustainable manner, and you need a tonne of water. If you work with what’s locally available, the maintenance cost is not as high, and you’re celebrating your own culture,” he says.
For Regenesis’ Reed, too much green infrastructure is about simply reducing the level of harm caused, rather than actively improving the world. The scale of the global environmental challenge means that many efforts, however positive and well-intentioned, ultimately “are not going to be enough” to stave off environmental catastrophe. And there is, of course, the risk that city greening becomes more about public perception than actually making a difference. “We need to move beyond nature as decoration to the understanding that all of these living systems have an integral role to play in our health,” he says.
Indeed, in Reed’s mind, the biophilia movement and emphasis on ecosystem services may even be obstacles, putting the focus on how humans can benefit, rather than the interrelationship between natural and human systems. “The biophilia movement can be seen as anthropocentric. It’s often about what nature can do for me, which is half the story. We also need to do for nature. It’s not about ‘impact’, it’s about ‘reciprocity’.”
Biophilic Cities proponent Beatley rejects this interpretation, contending that the movement is just as much about man’s impact on nature as nature’s impact on man. True or not, there is little doubt that increasing biodiversity for its own sake is a difficult sell — however terrifying the scientific data. “With climate change there’s an obvious target to aim for,” says WSP’s Merriman. “But it’s very hard with biodiversity because it’s not so tangible.”
So, what are the prospects for developing a more profound urban ecology? Reed says it is possible to galvanize action towards truly radical engagements and interactions — but only where clients and communities come together to jointly regenerate places based on a deep understanding of the local ecology. Cities, he says, can be “brought back to civility and high quality of life through paying attention to the unique human and natural patterns in each unique place”.
If that may sound a little New Age for some, Reed is not alone in sensing the limit of mainstream market mechanisms to address biodiversity in a genuinely effective way. WSP’s Butterworth makes the point that with regulation, government has the power to change the financial equations of development. “As soon as doing something becomes a requirement,” he says, “then the cost isn’t born by the developer, instead it just comes off the price of the land.” This is topical in the UK, given the proposal to enforce a biodiversity net gain on developments as a requirement of the planning system.
Even more fundamental would be a financial system that genuinely takes account of everything nature provides — something the concept of natural capital aims to put right. “We have to change the mindset that the environment is a cost,” argues Merriman. “Our current economic system makes it look like it makes sense to do certain things, simply because the environment is not factored in. We’ve got to change the system to recognize that development requires a healthy environment.”
The question is, can we do it in time?