Miyawaki urban forests to fight climate change and pollution issues
- Delhi, India

Establishing a Miyawaki forest in Delhi

The city of Delhi is rapidly expanding as more and more people are migrating to the city for better livelihoods and quality of life. Delhi expanded by 457 sqkm during 1989–2014 and the projections indicate that the city will expand by a further 787 sqkm by 2024. If not addressed in city planning, the uncontrolled expansion of the city will have several environmental implications.

While urbanization has its benefits, it also contributes to climate change and environmental degradation in multiple ways, including air, water, and land pollution, as well as the concentration of disaster impacts when urbanization is poorly implemented. Industrialization and market-driven urban expansion destroy local natural environments and have health implications.

Poorly planned infrastructure damages the local environment and blocks natural drainage. As a result, increasing incidences of urban floods from high-intensity rainfall events, and disruption of urban life have been reported throughout the country and several flood-related evacuation alerts have been issued in the city. Reduced infiltration opportunity time due to urban pavements and increased groundwater draw has led to rapid depletion of groundwater in the city. The negative impacts of urbanization are further exacerbated by increased high-intensity rainfall events, increased temperatures, and sea-level rise due to climate change.

Increasing population and urban expansion has resulted in the worsening of air and water pollution in the city leading to health issues and contributing to climate change feedback. Delhi is also suffering from rapid depletion of groundwater and groundwater pollution due to population growth and impervious land use.

Opportunities and pathways to advance the issue

Arresting urban environmental degradation can have multiple benefits from improving the health of individuals to contributing to climate change mitigation and Sustainable Development Goals. Given the environmental issues faced by Delhi, the Delhi Government has instituted several environmental measures, including expanding the urban green spaces, promoting eco clubs in schools and colleges, running public awareness campaigns, controlling pollution through strict vehicle testing, collaborating with NGOs to implement environmental programs, implementing carbon credit schemes (e.g., the regenerative braking of Delhi Metro rail), implementing cool roof programs through NGOs, supporting afforestation programs, monitoring of air quality, discouraging diesel vehicles by imposing additional taxes, making low Sulphur diesel available, increasing parklands, greening the Delhi Ridge Area, promoting rooftop rainwater harvesting systems, and implementing wastewater treatment facilities. Among these measures, the expansion of urban green areas by the afforestation of the Delhi Ridge Area and the planting of Miyawaki forests in selected locations in Delhi are recognized as an NbS.

Miyawaki forests are manmade forests where seedlings are planted at high density, usually up to 3–4 seedlings per square meter, in a random fashion. Seedlings are selected by giving priority to the local species that are already adapted to the local climatic conditions. Since seedlings are planted quite densely, natural selection ensures the emergence of healthy seedlings resulting in long-lasting vegetation. The Delhi Government has chosen two locations for establishing Miyawaki forests, one in Mayur Vihar and the other on the Yamuna Expressway. In these parks, 12,000 saplings of more than 25 indigenous species were planted in an acre of land. In comparison, only 1,000 saplings per acre are planted when using a traditional forest regeneration technique.

The decision to use the Miyawaki forest technique was based on the benefits that have been reported from previous projects. These include fostering a level of biodiversity several times higher than other traditional afforestation techniques, developing a dense forest that covers the ground and inhibits the growth of underlying vegetation and conserves soil moisture, improving soil organic matter content that promotes rich soil biota, mitigating soil erosion, recharging the groundwater aquifer, dampening sound pollution, acting as a windbreak to mitigate wind erosion, mitigating air pollution by acting as a physical barrier to air currents and contributing to the settling and filtering of dust and particulate matter in the air, and mitigating the urban heat island effect by cooling the air through evapotranspiration. The vertical stratification that develops by growing a combination of various tree species using the Miyawaki forest technique facilitates the efficient harvest of solar radiation and works as a strong wind barrier.

Key factors for success and replication

Miyawaki forests have been globally replicated with much success, including as an NbS. These experiences provide lessons for the successful implementation of the Miyawaki forest technique. The key factor for a successful Miyawaki forest is its self-sustaining nature, which originates from the stand density and the initiation of competition within the stand. Hence, it is essential to ensure that these basic requirements that characterize a Miyawaki forest are fulfilled. Since one of the main objectives of Miyawaki forests is to engender a human-nature relationship, appropriate tree species should be selected based on criteria for survival, environmental sustainability, and social acceptability. Hence, employing participatory techniques in species selection is one of the important steps in establishing a successful Miyawaki forest.

The involvement of the local NGOs and local citizens in planning and planting the forest is essential for the development of ownership and awareness among the citizens involved. Such engagement will also lead to a long-term relationship between local communities and the forest so that the community can continuously benefit from the ecosystem functions, such as clean air, water, rich biodiversity etc., generated by the forest. This means that the communities should be able to access Miyawaki forests, and that community activities, including recreational activities, in the vicinity of forests should be promoted. This will ensure that communities maximize the benefits of the forest. Engaging the local forest department has been found to be a useful means of building the capacity of forest officials as well as bridging relationships between the forest department and the community, which ultimately contributes to the successful maintenance and protection of the forest.