A small step towards a biotope in the city

Construction was completed in the spring of 2008. Observation of the habitat of living creatures began in July of the same year. When I first visited this biotope, I felt a certain nostalgia and gentleness reminiscent of a "satoyama" (a village mountain village), but at the same time, I was a little skeptical as to whether living creatures could really live in such a miniature garden on the rooftop of a building in the city center. However, within a year of its completion, this biotope has brilliantly blown away my doubts. There are no tall trees or bushes, and the vegetation is mainly grass and shrubs, so the variety is limited, but seven bird species were confirmed to live in the biotope once in autumn and winter and twice in spring, and an astonishing 133 insect species were confirmed to live in the biotope once in summer, autumn, and spring. Small birds were observed bathing and feeding, dragonflies and butterflies lived, and nymphs and grasshopper larvae were also observed. Moreover, all of these species were confirmed to live in the Imperial Palace and the surrounding green spaces. It is true that the Imperial Palace, with its vast green space covering an area of approximately 115 hectares, is located about 1 km west of Marunouchi. However, the fact that the creatures had actually flown beyond the outer gardens of the Imperial Palace, across the busy Uchibori-dori and Hibiya streets, and into a small biotope on the rooftop of a building in an office district with an employment population of over 240,000, was a truly moving event.

Not only in biotopes, but recently in parks and open spaces of buildings, we have come to see new Landscape Design with small waterfront spaces that evoke a nostalgic "satoyama" atmosphere. Unlike dynamic landscapes that create a certain sense of tension by arranging carefully selected varieties of vegetation in geometric patterns in response to the modern design of cities and Landscape Design, miniature garden designs made up of a variety of vegetation can look a little cluttered, but they are people-friendly and in contrast to modern cities and architecture, they are very refreshing in their own way. The author believes that the true value of this "satoyama" design is that, like small rooftop biotopes, it has the potential to provide a space where wild birds and insects can coexist in a city where people live in high density and carry out economic activities.

The concept of "biodiversity" has begun to be recognized as an important indicator in urban development, and a system for evaluating and certifying the environment has been established. In central Tokyo, there are forests and waterside areas where many living creatures live, not only around the Imperial Palace, but also Shinjuku Gyoen, Meiji Shrine, Koishikawa Korakuen, and the former Shirokane Imperial Estate. Is it possible to develop and link such "satoyama" Landscape Design, even if they are small, in the open spaces and rooftops of buildings around these many forests and waterside areas? Birds and insects that have been hiding in the forest until now may be seen in the office districts of the city center. Although there are only a limited number of bird and insect species that can coexist with humans in the special and limited space of a city, this small biotope on the rooftop of Marunouchi and the "satoyama" Landscape Design in the city center are still a small first step in creating a city that realizes "biodiversity."