What’s so great about Miyawaki pocket forests?

Did you know that native pocket forests grown using the Miyawaki method can be planted in spaces as small as 3m²? These forests mature up to ten times faster than traditional reforestation methods, require little to no maintenance after two to three years, and have biodiversity levels up to 18 times greater than traditional planting methods. Keep reading to learn more about the magic of Miyawaki pocket forests and how Carbon Positive Australia is helping to bring them to life.

The Miyawaki method of afforestation was developed by Professor Akira Miyawaki, a Japanese botanist and forest ecologist. This method involves careful species selection, specific soil preparation, very dense planting, a high diversity of species planted, and the key ingredient of community involvement.

Miyawaki pocket forests are ideal for urban environments because they create dense, biodiverse mini forests even on very small sites. These ‘pocket’ forests contribute to local health and wellbeing, reduce urban temperatures, and can help mitigate the impacts of climate change.

Native pocket forests grown using the Miyawaki method have the following advantages: 

• Usually the size of a small tennis court, however, can be planted in a space as small as 3m2;
• High density plantings of approximately 3-5 plants per square meter, with a selection of 30 or more species that are endemic to the area;
• Mature up to 10 times faster than traditional reforestation methods;
• These high density plantings offer greater potential for carbon sequestration per square meter than a traditional forest;
• Foster up to 18 times greater biodiversity levels than traditional planting methods;
• Require no maintenance within their first two to three years.

When you think of your urban environment, what comes to mind? Concrete and bitumen, right? Both of these materials absorb the sun’s heat during the day and release it at night, leading to higher temperatures in unshaded local areas. This, in turn, creates heat spots, which are areas of high intensity. Not so great, particularly during our Australian summers. 
 
Dr Thomas Longden from the Crawford School of Public Policy at ANU, found that there were over 36,000 deaths in Australia associated with extreme heat between 2006 and 2017¹. This is vastly more than all other natural disasters combined during the same period. 

Urban residential zones that lack tree cover tend to be lower income areas where people may lack access to air conditioning. Heat stress impacts those who may already be vulnerable and can exacerbate existing health conditions such as diabetes, kidney disease and heart disease. Older people are particularly impacted. Those on higher incomes or who live in leafy suburbs have more resilience to urban heat because they either live in cooler areas or have greater access to cooling. This means that urban heat is not only an environmental and health issue, it’s also an equity issue. 

When impervious surfaces like concrete and bitumen are shaded by trees, they absorb less heat, reducing the heat island effect. In fact, shaded surfaces may be as much as 11–25°C cooler than peak temperatures of unshaded surfaces around them, which has a significant impact on the liveability of local environments².  

Trees not only cool by providing shade; they also cool the air through evapotranspiration. They are essentially water pumps, drawing water up from the ground and releasing it into the atmosphere through the stomata on their leaves. As air temperatures go up, transpiration also increases. 

Native trees planted in urban areas provide a raft of benefits including: 

• Cooling impervious surfaces through shading;
• Cooling air temperatures through transpiration;
• Providing habitat for animals, birds and insects;
• Shading footpaths and bikeways making summer activity bearable;
• Creating beauty;
• Increasing health and wellbeing for both human and wildlife populations;
• Reducing the impacts of stormwater runoff;
• Drawing down carbon dioxide from the atmosphere;
• Noise reduction;
• Filtration of air pollutants.

Secondary benefits may also include: 

• A reduction in building energy costs where shade reduces the need for intensive air conditioning;
• Increased sense of wellbeing in communities with access to greenspace^3; 
• A reduction in costs of healthcare;
• A reduction in heat related deaths;
• Greater equity amongst urban communities.

The Miyawaki method of planting has some incredible advantages over traditional planting methods. Because the trees and shrubs are densely planted (up to 5 plants per m² as compared to one tree every 1.5m² to 2m² in standard reforestation), and grow fast because of both soil remediation methods and density: 

• The forest floor is rapidly shaded, so loses less water through evaporation, resulting in healthier soil;
• The trees and shrubs are quickly connected via mycorrhizal networks in the soil, allowing the sharing of nutrients and rapid growth (forest maturing up to 10 times faster than traditional techniques);
• Canopy cover is reached fast – in Far North Queensland, for example, it may only take 18 months;  
• Little to no maintenance is required after two to three years;
• Biodiversity levels in Miyawaki forests are up to 18 times greater than traditionally planted forests;
• The forest naturally and quickly expands beyond the planting area as birds drop seeds in and around the Miyawaki forest.  

Planting a Miyawaki pocket forest is a community endeavour, not a landscaping exercise. It’s an opportunity for local communities to learn about the benefits of trees and forests, to take local practical action on climate change, and to feel connected to the wellbeing of the environment they live and work in. 

At Carbon Positive Australia we want maximum positive impact created for every dollar donated to community planting. This means that we looking for community planting projects that have benefits beyond just planting trees. Pocket forests benefit the environment, local community health and wellbeing and reduce inequality. Miyawaki pocket forests do all of that and then some – maturing much faster than standard urban forestry, providing a very high level of biodiversity, and engaging the local community in climate action.

If you’d like to support projects like these, please donate here. 

If you have a Miyawaki pocket forest project proposal and would like to discuss funding and planting options with us, please email [email protected]

1. https://iceds.anu.edu.au/research/research-stories/we-know-heat-kills-accurately-measuring-these-deaths-will-help-us-assess 
2  Akbari, H., D. Kurn, et al. 1997. Peak power and cooling energy savings of shade trees. Energy and Buildings 25:139–148
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663018/