Manuel Marty

Narrow, loud, grey, dreary,…. These are just a few words that often come up in connection with cities. While more green areas have been created in cities in recent years, space is likely to become increasingly scarce in the future. So how can we make the best use of the little space we have?

One concept for using very limited space for greening as efficiently as possible is the so-called “Miyawaki forest” also known as the “tiny forest”. It has been described as follows: “A Tiny Forest is a dense, fast-growing native woodland that is around the size of a tennis court.” (Bruns et al., 2019).

The origin of the method

The concept was originally developed by the Japanese botanist and plant ecologist Akari Miyawaki (Webber, 2022). In his “Miyawaki method” he combines two concepts. One is the so-called “Chinju-no-mori”, which occur in his homeland of Japan. Whenever a new settlement was founded in early Japan, a forest was planted around the shrine there. What is important here is that these forests were always composed as far as possible in the same way as they originally occur in the region. The other concept he used was relatively new at the time, but is widely used today: Ecology (Miyawaki, 1999).

Another important figure who has helped the method to become more widely known is the Indian engineer Shubhenda Sharma. After participating in the construction of such a forest, led by Miyawaki, Sharma was so enthusiastic about the concept that he quit his job as an engineer and started his own company. “Afforestt” now helps plant tiny forests (a trademark of the company) all over the world (Bruns et al., 2019).

How it works

The main idea underlying the method and on which it is based is that plants that originally occur in the environment are already optimally adapted to it. However, as humans have changed their environment over time, this otherwise very stable systems has been increasingly replaced. If one wants to create a forest as it once existed in the respective place, various investigations are necessary to find the original species composition of the region.

Following Miyawaki’s method, the first step is to examine the vegetation that is present today. Thereby, relatively natural areas are examined as well as areas that have been affected by human activity (Miyawaki, 1999). The next step is to investigate which species form communities together. Similar species combinations are then compared to find the species that best complement the communities. Further studies on community structure, species interactions and so on follow and the results obtained are then recorded on vegetation maps (Miyawaki, 1999).

Subsequently, the concept of potential natural vegetation is applied. Potential natural vegetation is the vegetation that can persist on the land to be planted in the absence of human influence (Miyawaki, 1999). Miyawaki adopted this concept from Reinhold Tüxen, under whom he did his PhD in Germany (Webber, 2022). For Miyawaki, the resulting maps are indispensable: “Potential     natural    vegetation    maps    are   essential    for each  ecological   study  field  and  are  significant   as  ecological diagnoses     for    restoration of   green    environments.” (Miyawaki, 1999). The plants for the forest are then selected from the results of the PNV and the other ecological studies (Miyawaki, 1999).

After this very long analytical phase, the first practical implementation takes place. Seeds are collected from the selected plants and these are pre-grown in pots until they are about 30-50cm high (Miyawaki, 1999). Since in cities the top layer of soil has often been washed away, 20-30cm of new regional soil mixed with compost is placed at the site. The planting itself only follows after this (Miyawaki, 1999). The subsequent mulching minimizes moisture loss and soil erosion in the following period. The future forest must then be maintained for another 2-3 years until the top layer of the tree crowns closes and therefore prevents the growth of unwanted plants on the ground by itself (Miyawaki, 1999).

The plantation of a Miyawaki forest at Danehy Park in Cambridge, USA. (Source: SUGi Project)

Why to use or not to use it

As seen earlier, the Miyawaki method is a rather time-consuming and therefore comparatively more expensive method of creating a forest, which is probably not always used for that reason alone. So why should one take on such an effort?

There are some advantages of Miyawaki forests over those planted in the traditional way. One of the main points, as mentioned earlier, is that such forests are much more resilient than a completely artificial forest. The method can therefore also be used where others have had less success. This was the case, for example, in a project in the Mediterranean region, where traditional afforestation methods haven’t been successful (Schirone, Salis, & Vessella, 2011). Schirone, Salis & Vesella (2011) comment the results as follows: “…compared the  traditional reforestation techniques, plant biodiversity using the Miyawaki method appears very high, and the new coenosis (plant community) was able to evolve without further operative support after planting.”. This quote mentions another important point: increased biodiversity. The same was also found in a project in the Netherlands, where they created two forests using the Miaywaki method. The biodiversity found there was considerably higher in the newly planted forests compared to the reference forests (Ottburg et al., 2018). In times of great loss of diversity, such biodiversity islands could become very important, especially in species-poor areas such as cities.

At last, the effectiveness of the Miyawaki method should not be forgotten. Under normal conditions, it can take several hundred years for a natural stable forest (i.e. a climax society) to form (Miyawaki, 1999). Miyawaki (1999) himself points out that “several hundred years for reforestation is too long for us, however, because we live in a world where industry and urbanization are developing very rapidly.”. With his method, though, it is possible to shorten the time needed to establish a forest that is almost identical to a natural forest to a few decades (Miyawaki, 1999).

In addition to these advantages over forests planted according to classical methods, they also offer us the advantages that plants in cities generally provide. These include, for example positive, effects on mental health and reduced air pollution (Fineschi & Loreto, 2020). As native plants are used in the Miyawaki forests, the risk of invasive species being introduced by them, which is mentioned by Fineschi & Loreto (2020) as a big problem of green spaces in the city, is significantly reduced.

Another interesting and rather unusual example of why plants are important in cities was shown in Japan after a strong earthquake in 1995. Miyawaki (1999) could observe that vegetation could partly prevent the spread of fires. The plants also seem to have been beneficial for the residents of certain houses: “Some houses had evergreen trees around them in spite of their shade and falling leaves. These trees stopped the falling roofs and pillars and made openings in the rubble.” (Miyawaki, 1999).

Besides all the benefits of the Miyawaki method and of plants in cities in general, there are, of course, also some points of criticism. For example, the concept of potential natural vegetation, on which the Miyawaki method is based, is criticized for assuming a fixed vegetation. Natural systems are in fact not as unchangeable as they are considered to be in the sense of the theory (Chiarucci, Araújo, Decocq, Beierkuhnlein, & Fernández-Palacios, 2010). However, this is more of an observation in relation to the Miyawaki method and probably does little to change the usefulness of the method itself, especially when one considers the time periods over which the composition of such “natural vegetation” changes under natural conditions. Criticism of the method itself was especially made of the fact, that from an aesthetic point of view, such a forest does not necessarily correspond to our “ideal of beauty” of a forest with different ages, since all the trees were planted at about the same time (Webber, 2022). But as Webber (2022) says, the forest may not look pretty to us, but it still contains a well-functioning ecosystem.

Conclusion

In summary, it can be said that the method developed by Miyawaki, like so many other things, has its advantages and disadvantages. Nowadays, the main arguments against it are probably the higher costs and the increased labour input, but in its favour is the rapid development of a very stable system on a small area, as well as the increased biodiversity. It is therefore necessary to weigh up what points are important for a reforestation project.

The method is therefore not simply the one and only solution we need to make our cities and the green spaces in them more sustainable, but simply one of many parts that can contribute to this. It is important that we do not stand still, but continue to work on such new and innovative solutions for our future or as Miyawaki (1999) himself puts it: “We expect all scientists in the world to see our results positively and to begin to help make new affluent circumstances for the future in their own area. We hope to struggle together for creative ecology.”.

References

Bruns, M., Bleichrodt, D., Laine, E., van Toor, K., Dieho, W., Postma, L., & de Groot, M. (2019). Handbook – Tiny Forest Planting Method. (Merel den Otter & Lieke Kragt,Eds.). Amsterdam: IVN Natuureducatie. Retrieved April 2, 2022 from https://www.ivn.nl/tinyforest/tiny-forest-worldwide/resources-and-downloads

Chiarucci, A., Araújo, M. B., Decocq, G., Beierkuhnlein, C., & Fernández-Palacios, J. M. (2010). The concept of potential natural vegetation: an epitaph? Journal of Vegetation Science, 21(6), 1172–1178. Retrieved April 9, 2022 from https://doi.org/10.1111/J.1654-1103.2010.01218.X

Fineschi, S., & Loreto, F. (2020). A Survey of Multiple Interactions Between Plants and the Urban Environment. Frontiers in Forests and Global Change, 3. Retrieved April 2, 2022 from https://doi.org/10.3389/ffgc.2020.00030

Miyawaki, A. (1999). Creative Ecology Restoration of Native Forests by Native Trees. Plant Biotechnology, 16(1), 15–25. Retrieved April 2, 2022 from https://doi.org/10.5511/PLANTBIOTECHNOLOGY.16.15

Ottburg, F., Lammertsma, D., Bloem, J., Dimmers, W., Jansman, H., & Wegman, R. (2018). Tiny Forest Zaanstad – Citizen Science and determining biodiversity in Tiny Forest Zaanstad. Retrieved April 2, 2022 from Wageningen: https://research.wur.nl/en/publications/tiny-forest-zaanstad-citizen-science-and-determining-biodiversity

Schirone, B., Salis, A., & Vessella, F. (2011). Effectiveness of the Miyawaki method in Mediterranean forest restoration programs. Landscape and Ecological Engineering, 7(1), 81–92. Retrieved April 2, 2022 from https://doi.org/10.1007/S11355-010-0117-0

Webber, S. (2022). The Miyawaki Method for Creating Forests – Creating Tomorrow’s Forests | Restoring biodiversity by creating habitats and planting trees. Retrieved April 2, 2022, from https://www.creatingtomorrowsforests.co.uk/blog/the-miyawaki-method-for-creating-forests