As part of her master's thesis in the Urban Ecology programme at the Technical University of Berlin, Sina Franke took a close look at Miyawaki's Tiny Forest concept and used expert interviews and an area analysis to investigate whether these mini-forests could be a useful addition to the existing urban green infrastructure in Berlin. The results of the study show that Tiny Forests can have advantages over other urban green infrastructure in Berlin due to their special characteristics.
In the reforestation concept developed by Japanese plant biologist Akira Miyawaki, degraded areas are densely planted with tree and shrub species appropriate to the location. This method leads to rapid plant growth and binds CO2. In contrast to other green infrastructure elements in the city, Tiny Forests require less space and maintenance and are therefore a cost-effective alternative. As urban forests with limited space, they can also act as stepping stone biotopes and thus make an important contribution to preserving biodiversity in cities. In view of climate change, the ecosystem services provided by Tiny Forests in the city are considered to be of great importance. However, not only the ecological but also the social components play a key role in the concept. Citizens are actively involved in the planting and maintenance process, especially children. This participatory approach increases the social acceptance of Tiny Forests and has an impact on the urban population's perception of nature.
To find suitable locations for Tiny Forests in Berlin, a GIS analysis was carried out, taking into account two types of areas: fallow areas without vegetation and areas suitable for unsealing. It was then checked whether these areas are located in areas where it would make sense to expand the urban green infrastructure. This was checked using one of Berlin's five core environmental justice indicators - more precisely, the supply of green and open spaces. Berlin is the first metropolitan area in Germany to develop such a concept for environmental justice on a pilot basis. The total number of areas of both types of land was overlaid with the areas of Berlin that have a low level of green and open space provision in order to obtain an overview of only those areas that are located in areas with a low level of green and open space provision. These were areas in the centre of Berlin.
Key indicators for Berlin: lacking green spaces (red) in Berlin. Figure: Sina Franke.
As the literature base on Tiny Forests in relation to Central European metropolitan areas is rather small, interpretative knowledge was also gained for the study from interviews with experts. Four different areas were covered: implementation, nature conservation, politics and administration.
To summarise for Berlin, it can be said that the land potential with the parameters used is low. An extension to other types of land could therefore be advantageous. Further studies could also focus on areas outside the city centre, as the widespread implementation of Tiny Forests can generally be advantageous. It is also clear that Akira Miyawaki's original reforestation concept needs to be adapted for the urban context and further potential analyses carried out for suitable areas. Such an adaptation means that an expansion of native tree and shrub species to climate-adapted species can be useful and that suitable compositions can be tested experimentally in model projects. The exclusive use of native species according to Potential Natural Vegetation (PNV), as used in Miyawaki's original concept, is not readily transferable to anthropogenically modified sites such as cities. Cities are also increasingly struggling with the effects of urbanisation and climate change, which is why short and medium-term solutions are becoming more and more important. The demands on urban green and open spaces are also constantly increasing, which is why such areas should be designed to be multifunctional in order to meet the demands of the city. This is where Tiny Forests can be used to supplement the existing green infrastructure.
Tiny Forests need to be adapted to urban areas, then they can complement other green infrastructure. Photo: Martin Eggbert.
In recent years, the concept of Tiny Forests has also spread in Europe, particularly in urban areas, through initial pilot projects and it remains to be seen how these already established mini-forests will prove themselves. Further studies are needed to expand the state of research on the Tiny Forest concept, which originated in Asia, for European urban centres, to close knowledge gaps and to overcome implementation hurdles. In future, a standardised monitoring system for Tiny Forests in German cities could also be developed in order to be able to use the recorded parameters to make quantifiable statements about CO2 storage, for example.
- Sina Franke