Miyawaki Forests

The Miyawaki method, developed by Japanese botanist Akira Miyawaki in the early 1970s, focuses on rapid reforestation by planting dense clusters of native trees and understory plants. The method is gaining interest lately and is being tested in different applications around the globe, including a network of community planted "mini-forests" across Canada. So far, there are nearly a dozen in Ontario and Quebec, with plans in the works for many more across the country. 

The process involves selecting native species, improving the soil, and planting three seedlings per square meter to mimic natural forest growth. For the first few years, weeds may need to be removed, but after that, the forest is self-sustaining.

This method has gained popularity due to its quick results, minimal maintenance, and adaptability to small urban spaces, making it a promising solution for cities aiming to boost climate resilience. After all, the method was born from Japan’s era of industrial pollution and extraction. 

But the Miyawaki method quickly went international after being applied by Japan's Ministry of the Environment and large companies like the Mitsubishi Corporation. However, results have varied in tropical regions including Malaysia, where forest regeneration can take longer—up to 40-50 years compared to the 20 years expected in Japan. It's important to understand the method isn't effective, or at least not as quick, in other parts of the world and there are limitations to where it should be applied. 

How Does the Miyawaki Method Work?

The Miyawaki method replicates how a forest would naturally recolonize without human interference. Only native species that would occur naturally in that area without humans, given the specific climate, are planted. These indigenous plants have evolved over millennia to suit their environment, creating a self-supporting ecosystem. By reintroducing them, the Miyawaki method not only restores biodiversity but also creates a resilient site that is more responsive to climate change.

The Miyawaki method isn’t just unique because it restores native habitats using native trees; the afforestation principles are based on an understanding of how these species would interact in a natural forest. By planting a variety of trees close together, the method maximizes density and creates balance. Miyawaki forests can be established in small spaces, even as small as three square meters. Despite their size, these forests quickly become habitats for numerous species and provide a wide range of ecosystem services. These small, fast-growing forests are especially valuable for regenerating urban areas (not necessarily relevant to Canadian forestry plantings).

The close planting of diverse native trees boosts biodiversity by offering more food for pollinators, shelter for birds, and a cooler environment for insects. The dense canopy also shades out weeds and encourages leaf litter, which enhances soil fertility. Furthermore, planting various tree species ensures that if one is affected by disease, others can thrive in its place.

The method and it's steps are similar to any native planting, and these general steps could be applied to recreating different forest or prairie habitats of North America too. 

Research:

When planting a Miyawaki forest, the first step is to identify the native vegetation best suited to the area being planted, termed "Potential Natural Vegetation". To establish this, our forest makers do intensive research, often involving the indigenous community. They look to see what is growing locally, in protected areas or ancient old-growth forests.

Forests are multi-layered, and as the Miyawaki method mirrors nature, we identify and plant four layers of vegetation, building a resilient green wall of canopy trees, trees, sub-trees and shrubs. We select up to 40  different species to create balance and maximise density.

Site Preparation:

The soil must be prepared, especially in degraded areas, to support tree growth. This involves working the soil once to restore its biology, making it soft, fungi-rich, and fertile. Compost tea with beneficial fungi is added to improve nutrient availability and boost tree root development.

Planting:

Young saplings are planted densely, three to four per square meter, in a natural pattern to simulate forest growth. Young saplings are more adaptable and can form symbiotic relationships with mycorrhizal fungi in the soil far quicker than an older tree. The dense planting enhances biodiversity, improves carbon capture, filters pollutants, and increases resilience against floods and landslides. The canopy provides shade, reduces rainfall impact, and cools the environment.

Mulching:

After planting, a thick layer of organic mulch like straw or woodchips is applied to protect the soil and retain moisture. Mulching also helps build soil fertility by supporting beneficial insects and microbes. The forest needs minimal maintenance for the first two to three years, after which it becomes self-sustaining.

Whatever its charms, the Miyawaki method shouldn’t prevent us from thinking critically about ecosystems and their endless variety, nor about the pressing need to protect Earth’s remaining “native, natural forests” before we need to engineer copies.