Designing the Future of Sustainable Cities

Yoshiki Harada
Associate Professor, Faculty of Science and Engineering, Chuo University
Areas of Specialization: Environmental Design, Urban Greening, and Urban Planning

Adaptive management for greening

My research theme is urban greening. To pursue this theme, I spent 15 years in the United States practicing and teaching urban planning and conducting R&D on advanced greening technology (1, 2). For example, I experimented with creating a forest in a large city. During his tenure as mayor of New York City (2002-2013), Mr. Bloomberg, the founder of Bloomberg L.P., implemented a series of large-scale projects to realize a sustainable city. One of these projects was Million Trees NYC, which aims to plant one million new trees along streets and in parks. I participated in this project through my position as a Research Assistant/Fellow at Yale School of the Environment. Through a demonstration experiment in which my research group actually raised 1,300 trees, we gathered evidence to identify the optimal methods of selecting and cultivating tree species(3). It is rare for knowledge about plants and soil to be verified and applied on such a large scale in a metropolis like New York. In the past, very little research has been conducted on the function of plants and soil in highly urbanized environments. Furthermore, predicting such functions is becoming even more difficult due to changing precipitation patterns and temperatures caused by climate change. Even under these uncertain circumstances, we continued to hold various events for Million Trees NYC with the participation of everyone involved and proceeded with discussions, research, and the actual planting of trees. The event was attended not only by staff from the New York City's landscaping bureau and nature conservation departments, but also by experts from the city's botanical gardens, teachers and students from elementary, junior high, and high schools, designers from local environmental design offices, engineers from environmental consulting firms, and researchers like ourselves from universities. Participants conduct experiments while creating urban greenery, and revise plans during experimentation. This method is called adaptive management. I believe that the form of society that invigorates and supports such a method is a feature that Japan should study from overseas case examples (4, 5, 6).

Managing the dreams of society

Urban greening contains dreams for the future and has the power to transform society. However, in addition to advanced technology established based on evidence, there are also rumors and beliefs mixed into this dream. As a result, verification by experts is required. For example, I personally conducted empirical research on large rooftop vegetable gardens. In these gardens, the food waste that overflows in large cities is composted to create artificial soil for rooftop greening. Moreover, by growing vegetables on roofs and supplying the vegetables directly to the local metropolis, these gardens also make effective use of rainwater and carbon dioxide, which are often a problem in cities. Based on hopes for such benefits, the Brooklyn Grange at Brooklyn Navy Yard was born. At the time of its construction, it was the world's largest rooftop vegetable garden. As a Research Assistant/Fellow at Cornell University's Urban Horticulture Institute, I spent five years evaluating the performance of vegetable gardens with support from the United States Department of Agriculture (USDA) (7, 8, 9, 10, 11). As a result, I found that even though there is sufficient rainfall to grow vegetables, a large amount of water is wasted when it leaks from the artificial soil during rainfall and watering. Large amounts of fertilizer components were dissolved in the leaking wastewater, resulting in more than 60% of the nitrogen fertilizer applied to rooftop gardens being wasted. This leads to poor water quality and increased maintenance costs. Based on this performance evaluation research, I developed artificial soil for making effective use of water and fertilizer (11, 12). I utilized this technology to create the Brooklyn Grange at Sunset Park, which is currently the world's largest rooftop vegetable garden. Similar to a large rooftop vegetable garden, greening projects transform the dreams of society into a reality. Such projects are rapidly increasing in urban planning and are forming a huge market internationally. In order to effectively utilize this momentum and realize sustainable cities, it is necessary to explain to society the discrepancy between expectations and reality and to develop technologies that improve reality(1).

Carbon management from Japan

In my research, charcoal is the bridge between the United States and Japan. Charcoal which is made primarily from plant-based materials is called biochar. I am continuing to research biochar as a material for making artificial soil and for improving soil (11, 12, 13, 14). As I mentioned earlier when discussing soil development for rooftop vegetable gardens, I am developing technology that will reduce the amount of water and fertilizer components that are wastefully leaked from the soil, and will also significantly increase the proportion of components that can be absorbed by crops. Biochar is also attracting a lot of attention as a technology for realizing a low-carbon society. For example, if fresh-cut plants are left unattended, they will quickly be decomposed by microorganisms. As a result, the large amounts of carbon dioxide fixed through photosynthesis will be released into the atmosphere. However, biochar has almost no decomposition by microorganisms. Therefore, it is possible to store large amounts of carbon underground by mixing biochar with soil or creating soil using biochar as a material.

In the United States, I continued to collaborate with Johannes Lehmann of Cornell University, who is a leading expert on biochar research. Immediately after returning to Japan in 2020, I established the Urban Ecology Lab at Chuo University's Faculty of Science and Engineering. I am currently conducting joint research and development on bamboo charcoal with local companies in Nagano Prefecture (13, 14). Bamboo is dense, fast growing, and regenerates every year. Due to these characteristics, producing biochar from bamboo can significantly increase production efficiency. Furthermore, the rapid expansion of abandoned bamboo forests poses a threat to the conservation of Japan's mountain forest ecosystem. It is therefore necessary to increase the added value of bamboo and promote bamboo forest maintenance. Biochar research is mainly progressing in developed countries where forestry is popular. Charcoal is the main ingredient, but there are very few countries or regions that are focusing on bamboo charcoal. My goal is to establish soil technology that utilizes bamboo charcoal and then export Japan's carbon management technology to the world.

Urban greening as integrated science and engineering

When reflecting on urban greening technology in the first two decades of the 21st century, the focus has been on the environmental aspects (biophysical dimensions) of large cities. Specifically, plants, soil, water, fertilizer components, etc., are the direct subjects of research. All of the research already mentioned in this article falls under this category. However, the outbreak of COVID-19 has triggered opportunities for various experiments involving the entire world and has brought about major changes in research and development in the field of urban greening as well. During the COVID-19 pandemic, declining levels of health and well-being have become a social issue due to restrictions on movement at various spatial scales, from entire cities to homes and rooms. The moment that this problem was exposed, countless research projects were launched around the world. These projects closely examined the environmental design that encompassed the behavioral ranges of people living in cities, and reports began to be issued on the various effects that movement restrictions had on people's subjective levels of happiness and health. As a result, many cases of urban greening contributing to the maintenance and improvement of health and well-being have been reported in leading international journals. This marks the beginning of a new era in which urban greening integrates both the environmental aspects (biophysical dimensions) and human aspects (human dimensions) of large cities. My laboratory is working to establish a series of methods to quantify the various impacts that urban greening has on humans (15, 16). For example, in addition to urban greening research in the environmental field, we also study the stress-reducing effects of urban greening, the impressions that related designs give to visitors, and the amount people are willing to pay for these effects and designs.

In the field of society, I have pursued the form of evidence-based practices. When working at research institutions, I have pursued the development of technologies that are useful in the field of society. In this way, I understand both the field of science and the science in the field. Furthermore, I have transcended national boundaries and disciplines to work on urban greening at six universities across fields such as science and engineering, agriculture, and design. I aim to fully utilize these experiences in order to establish a new world of urban greening as an integrated science and engineering field.

(1) Harada, Y. (2015). Working Abroad as an Architect:Urban and Landscape Design: Japan. Gakugei Shuppansha, 2015 (authored the chapter entitled "Metropolitan Ecology Taking Place in New York City").
(2) Harada, Y. (2015). Urban Design and Diverse Ecologies in the United States. Journal of the Japanese Institute of Landscape Architecture, 78(4), pp. 321-324.
(3) Oldfield, E. E., Felson, A. J., Auyeung, D. N., Crowther, T. W., Sonti, N. F., Harada, Y., ... & Bradford, M. A. (2015). Growing the urban forest: tree performance in response to biotic and abiotic land management. Restoration Ecology, 23(5), pp. 707-718.
(4) Harada, Y. (2017). Urban Long-Term Ecological Research and Green Infrastructure Projects. Landscape Ecology, 21(2), pp. 89-95.
(5) Harada, Y. (2014). Landscape Structure, Function, and Change. Journal of the Japanese Institute of Landscape Architecture, 78(1), pp. 32-38.
(6) Green Infrastructure, Japan. Nikkei BP Marketing, 2017 (authored the chapter entitled "Green Infrastructure in Areas Surrounding New York City and Future Urban Ecology).
(7) Harada, Y., Whitlow, T. H., Todd Walter, M., Bassuk, N. L., Russell-Anelli, J., & Schindelbeck, R. R. (2018). Hydrology of the Brooklyn Grange, an urban rooftop farm. Urban ecosystems, 21, pp. 673-689.
(8) Harada, Y., Whitlow, T. H., Templer, P. H., Howarth, R. W., Walter, M. T., Bassuk, N. L., & Russell-Anelli, J. (2018). Nitrogen biogeochemistry of an urban rooftop farm. Frontiers in Ecology and Evolution, 6, p. 153.
(9) Harada, Y., Whitlow, T. H., Russell-Anelli, J., Walter, M. T., Bassuk, N. L., & Rutzke, M. A. (2019). The heavy metal budget of an urban rooftop farm. Science of the Total Environment, 660, pp. 115-125.
(10) Harada, Y., & Whitlow, T. H. (2020). Urban rooftop agriculture: challenges to science and practice. Frontiers in Sustainable Food Systems, 4, p. 76.
(11) Harada, Y., Whitlow, T. H., Bassuk, N. L., & Russell-Anelli, J. (2017). Biogeochemistry of rooftop farm soils. In Urban Soils (pp. 275-294). CRC Press.
(12) Harada, Y., Whitlow, T. H., Bassuk, N. L., & Russell-Anelli, J. (2020). Rooftop farm soils for sustainable water and nitrogen management. Frontiers in Sustainable Food Systems, 4, p. 123.
(13) Moro, K., Ito, N., Furusawa, R., Ito, M., Nakajima, K., & Harada, Y. (2022). Cooling effect of growing substrates amended with bamboo biochar. Journal of the Japanese Society of Revegetation Technology, 47(4), pp. 495-504.
(14) Harada, Y. (2021). Applied Practices of Urban Ecology in a Changing World. Journal of the Japanese Institute of Landscape Architecture, 85(2), pp. 144-145.
(15) Tashiro, M., Kyutoku, Y., Niioka, K., & Harada, Y. (2022). Rating of immersive virtual reality used in the contingent valuation method for valuing an urban park featuring ponds. Journal of the Japanese Society of Revegetation Technology, 48(2), pp. 364-373.
(16) Kobori, M., Niioka, K., Ito, M., & Harada, Y. (2023). Levels of stress reduction in biophilic indoor environments compared among experiments using different stressor tasks. Journal of the Japanese Society of Revegetation Technology, 48(3), pp. 516-526.

Yoshiki Harada/Associate Professor, Faculty of Science and Engineering, Chuo University Areas of Specialization: Environmental Design, Urban Greening, and Urban Planning

Yoshiki Harada graduated from the Department of Architecture in the Faculty of Science and Engineering, Waseda University, and completed a master’s degree at the University of Tokyo Interfaculty Initiative in Information Studies (Housing and Urban Analysis Laboratory). He also graduated from the Department of Landscape Architecture in the Graduate School of Design, Harvard University, and received his PhD from the School of Integrative Plant Science, Cornell University. After his professional experience as an urban planner and designer in New York City, and after his fellow positions at Yale School of the Environment and Cornell University’s Urban Horticulture Institute, he founded the Urban Ecology Laboratory in the Faculty of Science and Engineering, Chuo University.
His works as a designer include Race Street Pier Park in Philadelphia and Manhattanville at Columbia University, New York City.
His co-authored books including “Green Infrastructure”(Nikkei BP, ISBN-10 :‎482223522X), “Working Abroad as an Architect:Urban and Landscape Design” (Gakugei Publishing), and more.