The Urban Restoration: How Miyawaki Micro-Forests are Rewiring the Modern Jungle

Urban surfaces generally are made from asphalt or concrete, which soak up a lot of solar energy during the day, holding it until night, and causing cities to be much hotter than the surrounding areas. For a long time, we've thought of cities and nature as two very different things: cities are monuments to human industry, and nature is a place where wild things grow.

Illustration by The Geostrata

But this separation is proving deadly as the world's cities grow and the "Urban Heat Island" effect turns our streets into ovens.

The standard way to add greenery to cities is to plant manicured lawns and isolated, decorative trees. This is a cosmetic fix for a structural problem. Our cities need more than just "green space" to last the next hundred years. They need ecosystems that can sustain themselves. Japanese botanist Akira Miyawaki came up with the radical Miyawaki Method. It's not just a gardening trend; it's a type of biological engineering that lets us grow a forest that is a thousand years old in just thirty years, turning forgotten city corners into lungs of the future.

THE PHILOSOPHY OF NATURAL COMPETITION

At the core of the Miyawaki Method is a deeply-held conviction about the importance of potential natural vegetation (PNV). Traditional forestry views trees based primarily on aesthetic and timber yield aspects, planting them in straight lines with large spacing. However, Akira Miyawaki recognised these practices as being fundamentally wrong because in a truly wild, primary forest, trees do not grow in isolation they grow in large, dense communities of many different species all growing together.

The Miyawaki Method replicates this 'beautiful chaos' by using native species of trees planted at an extremely high density (3-4 saplings per square metre). This creates an immediate state of biological tension because there is no lateral growth possible. Therefore, the trees grow straight up to the sunlight. 

The result of this artificially created competition is a tenfold increase in growth rates compared to traditional techniques, thereby enabling us to "hack" the timeline of natural succession.

The aesthetic aspect of a Miyawaki forest is stunning, but the most remarkable part of its creation happens below the surface. Before a single sapling is planted, the urban soil, usually degraded and compacted, is completely transformed. This process is referred to as “soil alchemy” which involves deep digging to amend the soil with organic matter, moisture-retaining materials (such as coco peat), and natural fertiliser prior to planting. The goal of this soil preparation process is to create a soil environment with porosity and nutrient availability comparable to that of a forest floor that has been undisturbed for centuries.

This type of soil preparation will promote the establishment of Mycorrhizal networks that are more rapidly formed. Mycorrhizal networks allow for various species’ root systems to be interconnected, thereby allowing them to share nutrients, moisture, and even chemical signals that can be used as an alarm for pest infestations. By concentrating on the health of the soil before creating the forest, the Miyawaki Method promotes the creation of a large, community-based super-organism rather than simply a collection of individual plants.

THE MULTI-LAYERED SHIELD OF BIODIVERSITY

The Miyawaki forest is characterised by 4 distinct vertical layers: shrub (the ground), sub-tree (20% of plants), canopy (60% of plants), emergent (20% of VPP's). This vertical structure gives this food growing method an incredible density due to having as much as thirty times the surface area of leaves found in traditional park settings. 

The layers of vegetation form an effective biological barrier to cities, with the foliage providing a massive carbon sink that is absorbing significantly greater amounts of CO2 than what a monoculture produces. In addition to being usable by humans, as mentioned earlier, the multi-layered canopies also serve as an effective sound barrier blocking much of the sound created by traffic, industry and other activities occurring within urban areas. Lastly, these forests become instant centres of biodiversity. 

In light of the decline in urban insect and bird life rates, the Miyawaki forest will provide a habitat for many different types of creatures to access food and nesting opportunities at multiple levels, within an area the size of a few parking stalls.

THE URBAN HEAT ISLAND AND THE NATURAL COOLER

The urban heat island effect is being mitigated by these micro ecosystems, which is one of their most important benefits.. The air conditioning effect relies on evapotranspiration, which is how air is cooled through moisture released by trees. As trees continue to "breathe" (release moisture), they will lower the surrounding air temperature of their neighbourhood by as much as 15 °C. Dense tree cover does not allow for the ground to warm and dry out as occurs in traditional parks with scattered trees.

Therefore, these micro-ecosystems create a cool and humid microclimate and result in a tangible and physical relief from the heat for people living in and around cities. Nature ultimately is the best functional climate technology.

One of the main reasons why people do not support urban forestry is due to how expensive it is to maintain over time. Most conventional parks are regularly watered, trimmed, and treated with chemical fertilisers to maintain an aesthetically appearing landscape. To each his/her own, but the Miyawaki Method flips this typical cost model upside down because it supports self-sufficiency. For the first two to three years after the establishment of a Miyawaki Forest, the young trees will need to be weeded and watered on a consistent basis until the completing of the canopy's closure, meaning that the leaves of the trees are touching each other and preventing sunlight from getting to the ground.

Once this occurs, the forest becomes self-sustaining. Since there are no longer any sources of sunlight for the weeds, the thick blanket of mulch (leaves) that have fallen from the canopy of the trees will keep the moisture in the soil, and the mature root systems within the community will become responsible for managing nutrients. After this initial phase of establishment, no human assistance or support will be required for the maintenance of the forest (the ecosystem becomes "set-and-forget"). In fact, the less that humans interfere with the Miyawaki Forest or environment, the stronger and more resilient it will become.

The ingenious thing about the "pocket forest" is its ability to survive under some of the most adverse conditions imaginable. Since the method is designed for small-scale applications, it is perfectly suited to be used within the "dead zones" of urban planning, areas such as the triangle of dirt within the cloverleaf of a highway, the narrow strip of land behind a factory, or a vacant lot between a pair of high-rises.

None of these places would ever be considered useful; but they are precisely where the impact of a micro-forest can have the largest effect. By reclaiming these small parcels of land, we are able to create a "green corridor" that travels throughout the city, thereby allowing wildlife to migrate and remain connected rather than becoming trapped in isolated areas. This also means that anyone can now enjoy nature and take advantage of its calming presence.

THE FUTURE OF RESILIENT URBANISM

With climate change becoming a billowing cyclone of uncertainty, the Miyawaki Method is a change in view of the way we have to think about urban resilience. We are moving away from "grey infrastructure" (pipes, walls, and A/C) to "green infrastructure" (forests). The micro-forest is a multi-functional tool that grows: it prevents excess rainwater through its porous soil from becoming a flash flood, cleans the air of particulate pollution, and creates an oasis of calm for a very stressed community.

The challenge that we face now is how to scale this local "insurgency" to a global standard. Each city has thousands of square meters of "wasted" land that could be transformed into cooling, carbon-sequestering machines. By utilising the Miyawaki Method, we are not simply planting trees; we are bringing the ancient knowledge of the forest into the heart of the modern urban environment and creating a habitable, vibrant, and alive city.

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BY MUSKAN GUPTA

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