Tree height monitoring in Miyawaki Forests

“We do not inherit the earth from our ancestors; we borrow it from our children.”-David Brower

In this blog, landscape architect Aravind shares fascinating insights from his master’s dissertation…

The climate crisis has prompted some of the biggest threat humans are facing now. Fluctuations in rainfall, unexpected weather changes, rise in sea levels, natural disasters and change in salinity and acidity of oceans are some of the most noticeable effects of this. Afforestation is one of the most sustainable weapons humans could use to fight this crisis.

The Miyawaki Forest method is one such afforestation technique which is quickly gaining grip across the world. This approach found its way to the UK recently (around 2021) and has since then been implemented in hundreds of sites across the country.

Miyawaki Forest is a forest creation methodology invented by Akira Miyawaki, a Japanese botanist in the 1970s. It was developed as a method of creating thick forest on degraded land. For a forest planting to reach its full maturity through natural succession, it takes centuries. Miyawaki Forest expedites this to a matter of decades. This method involves planting trees at high densities (around 3 per sqm) into soil prepared with organic matter and other missing minerals to replicate the soil in a mature forest.

Here are some interesting details about Miyawaki Forests:

• The method results in faster-growing, tall, extremely dense forests in a short time.
• It could be an effective method to create urban forests especially when land available is scarce.
• The higher planting density means more plant saplings and thus it does demand an increased cost. Also, the method involves initial preparation of soil with organic matter, and this can increase the initial cost and requires maintenance for the first 3 years but once the forest establishes, it becomes a self-sustaining habitat.
• The density of the forest (around 3 tree saplings per sqm when planting) can be an issue for security if used in areas where access is necessary, especially in an urban context.
• The forest has shown promising retention rates (85%) in the UK after 2 years of planting.

My research was aimed at understanding the accuracy and usability of LiDAR based mobile applications over conventional methods used in forestry, in the context of using citizen scientists for monitoring Miyawaki Forests. The research involved measuring height of 36 trees across four Miyawaki and two non Miyawaki sites in Oxford and Sheffield using fellow coresearchers and friends as citizen scientists. Each tree was measured using five measurement methods and statistically and graphically compared to understand accuracy. The results from the analysis show that the mobile applications I tried out are promising, but not yet at satisfactory levels of accuracy and need further hardware and software development.

The research helped me understand the Miyawaki planting technique in depth and see how it performs on the ground in the UK. The sites I visited showed promising growth rate compared to other forest planting techniques. Citizen scientists were monitoring the sites I visited, which gives the public a sense of ownership over the forests and thus improves their perception of green spaces and makes them value them more.