1. Introduction

potscape is described as a complex, inter-connected spatial realm which is determined by simple potted plants. This potscape is topic of the thesis, which focuses on the potted plant gardens of Tokyo.

potscape is a product of people.

Steven Whitford has stated that "Tokyo is a city where people who don't have power, produce incredible results." People left out of planning, who do not profit from planning processes, living under conditions only marginally regarded by planners, in short -with no power- shape their living environment in incredible ways as the example of Tokyo's flower pot gardens shows.

potscape is green space as Tokyo does not strike the visitor as a city of parks, however this does not imply the city lacks greenery. In fact, countless streets in Tokyo possess extraordinary green spaces. Residents, shopkeepers or their employees improvise gardens through the use of adjacent street space. These gardens consist of countless flower pots and boxes, carefully arranged in various sizes and planted with all kinds of plants imaginable: palm trees, bonsai, cacti, summer flowers, conifers, shrubs, or even rice.

Aim of the research is to frame potscape in a spatial concept and to examine the parameter which foster the hybrid landscape of flower pot gardens.

Hybrid landscape has been described as: "a landscape that has communally accepted structure and rules while displaying the richness and diversity that only comes from the creativity of many individuals." (Quayle, Driessen van der Lieck 1997: 100) Therefore the perspective of hybrid landscape, an idea that conflates officially planned spaces and spontaneously made places into one concept of space in the urban landscape, is the chosen perspective for this research.

Further, the thesis is delimited by the approach from a landscape architectural perspective and the fact that little substantial research on the flower pot gardens exists.

The paradox which lies between the large potential and the marginalization of daily life environments is viewed as the main problem of this research.

The main question of this research is: What are the parameters of hybrid landscape which can be integrated in successful urban design?

This research aims to identify parameter which are related with informal structures in order to integrate knowledge on these into urban design strategies. I claim, that the flower pot gardens possess qualities which will lead to a better understanding of the concept of hybrid landscape.

The hypothesis of this research is: The flower pot gardens can serve as a tool to understand and integrate planned and informal spaces in the concept of hybrid landscape.

Methods used in the research are wide ranging from literature to field research. Core of the thesis is a case study of four areas in Tokyo's shitamachi. There spatial analysis, analysis of the flower pot gardens and their complexity and interviews conducted with residents compile a comprehensive image of the places that foster hybrid landscape.

2. Flower pot gardens

Chapter II gives a comprehensive overview of the Japanese flower pot garden culture and aims to illuminate questions on background and culture of gardening in limited space. What are flower pot gardens? How can they be described, what are their functions, how are they rooted in Japanese traditions such as bonsai and city- and building structure? What are functions they fulfill today. The chapter concludes with a review of conducted research on flower pot gardens.

3. Case study

Chapter III presents the case study on the hybrid landscape of flower pot gardens in four areas in Tokyo. Prior to the case study, the methodology of the case study research is illustrated in detail as the complexity of the topic requires a detailed explanation of approach and method. Among others, process of case selection and the units of analysis are examined. In the case study, detailed background on spatial structure and its qualitative ramification is given. Transcripts of interviews with residents provide an in-depth understanding of the places and the flower pot garden culture. In the following, the case study is evaluated and the evaluation of a ward office survey is included to conclude the detailed investigation.

4. Hybrid landscape

In chapter IV the concept of hybrid landscape is set in the center. It is examined how hybrid landscape has been defined, and what aspects can contribute to a broader understanding of the term. Commencing with the consequences of the modernist movement, aspects of vernacular architecture, appropriation of space and political appropriation of space, concepts of space and place, private and public and lastly garden are set into context with hybrid landscape in the example of flower pot gardens.

5. Discussion & Conclusions

Key findings of the research question the link of flower pot gardens and roji-kukan. It is concluded that potscape is the result of alleyization processes and no longer restricted to roji. In contrast, the research showed that most gardens are found in wider streets, where more space allows more differentiated uses. It is further highlighted that Japanese scholars even include potted plants in the definition of roji, even though not yet consciously.

Moreover, high-rise developments are found to be responsible for the decline of the hybrid landscape of flower pot gardens in Tokyo.

Further, in total 91% of all flower pot gardens were found to be associated with residential uses. Therefore, one of the -not so surprising- findings to emerge from this study is that appropriation of space and place making are clearly related to individual intervention, which is more likely to occur when identification with place exists.

In examining the relationship between flower pot gardens and whether they were placed in private or public spaces it was found that 53% of flower pot gardens were found to be located outside of private space. Thus, this finding has to be carefully evaluated: in the areas were it was possible to place the plants on private ground, most people did so.

The relation between quality of environment, which was measured through the evaluation of place relevant data, and the amount of flower pot gardens was shown to be significant: in areas with less place qualities the amount of flower pot gardens was lower than in the areas where these qualities were valued higher.

In conversation with residents it became clear that, aside from reasons derived from culture, tradition or the present cityscape, the main reason for keeping a flowerpot garden is simply personal fulfillment in caring for plants, working with one's own hands and creating living, thriving, blossoming compositions of plants to enjoy, show and share.

Through the interviews it could be shown that the flower pot garden culture is based on long tradition, most gardens were older than 20 years. Many interviewees stated that they had inherited their garden and love for plants through their parents.

It was found that most people interviewed, clearly regard their flower pot gardens as private, regardless whether placed on public or private land.

The ward office survey showed that both municipalities involved (Taito-ward, Chuo-ward) did not have regulations dealing with the private appropriation of space through flower pot gardens. However, in a somewhat undecided approach both wards stated the potential they saw in the gardens as green space.

Suggestions for formal planning processes derived from the research are:

Most important, it has to be emphasized that hybrid landscape can not be formally created, implemented or designed. Consequently planning merely can help to facilitate the conditions under which it can emerge - and planning can eventually also determine whether a rich hybrid landscape will emerge -or not.

Lower the threshold for hybrid landscape

"Imperfect" spaces attract people to beautify and encourage involvement.

In Tokyo roadside trees and flowerbeds often function as gardens because the threshold to "illegal" space use is lowered: these are spaces for green and the monotonous azalea hedges can be replaced by something more beautiful in a discreet way.

View privacy as part of public and vice versa

People who shape their environment physically do so to manifest privacy and to express individuality. Yet, this does not mean that public is excluded, it is rather a necessary part supplementing privacy. In the expression "private for the public" which was often used by the interviewees to describe the relationship between private and public it becomes evident that private and public are a supplementary pair.

Consider scale

The expression of individual creativity still exists in apartment towers. Yet on the 11th floor balcony the plants kept there are no benefit for public and community. This might be no new perception - still the widespread trend to the modernist "tower in the park" concept now encouraged by Tokyo's city government and numerous investors will eventually destroy the flower pot garden culture.

Use plants, and let people use plants

One characteristic of the flower pot gardens is their floating existence between private and public. They are private goods, in public realm, fuzziness and organic growth further blur the boundary between the entities. Private effort and public space is shared for the good of a natural creation.

Plants signify caring, safety and peacefulness. Where well kept flower arrangements are found, people caring for them are usually not far.

The flower pot gardens reflect the human need for nature. In total estrangement from nature, these gardens are often the only natural element left in the vast concrete jungle of Tokyo. The study has shown that gardens possess qualities which lead us back to the root of our human existence. In a less abstract sense, plants have been proven to reduce stress, violence, and lead to higher levels of cognition, apart from their benefits on eco systems, climate, air quality and habitats. Humans are part or nature- this is as it seems easily forgotten.

The combination of the positive effects of plants and participation of people in shaping their environment is not easily surpassed in terms of benefits for humans and eco systems. Tokyo has the tremendous potential of people who are willing to share their personal efforts of shaping the environment -for themselves and for everybody else. However, this potential has to be recognized, supported and included in academic discourse as a valid strategy for sustainable development of Tokyo.

Figure 1. potscape- Tokyo's informal flower pot gardens.

本論文は、東京下町で私有地からはみ出して街路に置かれる「鉢植え」に着目し、都市空間における公私境界のバナキュラーな在り方について、調査と分析を行っている。鉢植えから都市空間の様相の一端を解明しようとする着想は非常に独創的である。また、東京下町での緻密な調査は資料的な価値も高い。現地サーベイとインタビューなどの調査から得られた分析は、これまでの都市空間研究とは異なり、生活者と都市空間との関わりの一類型を新たに提示したといえる。

第1章では、研究手法と仮説が提示される.第2章では、調査対象である街路に置かれる鉢植えの定義とその歴史的解釈、さらには東京における鉢植えの使用状況などを整理している。第3章では、浅草・根岸・月島・谷中の街路空間における鉢植えの分布と使われ方の調査結果をまとめている。ここで示された綿密な調査を踏まえて、続く第4章においては「Hybrid Landscape」という概念の提出がなされ、第5章では全体を総括する結論が示されている。さらに、都市空間における鉢植えと、日本人の有する自然観との関係を指摘した上で、鉢植えをおくという行為が、都市生活者の自然への希求と関連づけている。今回の調査によって、調査対象のうち91%の鉢植えが居住者の所有物もしくは、何らかの関係があることが指摘されており、さらに鉢植えのうちの53%が、公共空間と私的空間の境界上におかれていることから、鉢植えと公私境界の関連について指摘している。

本論文で提出された「Hybrid Landscape」という新しい概念は、東京の都市景観を研究する上で、重要なものとなる可能性がある。近代化の過程において、日本の都市は西洋から多くのものを取り入れながらも、現在の東京は西洋の都市とはかけ離れた都市景観を獲得している。その構成要素の一つとして、公私の境を曖昧にする鉢植えなどの私有物がある。

このような公共空間へのインフォーマルな浸食は、生活者の外部空間への関与の仕方、公私の力関係、都市への態度表明などの現れと見ることも出来る。つまり、公共空間の部分的私有化に着目することは、生活者(私)と都市空間(公)との関係の在り方を解明する一つの方法といえる。この観点から、本論文によって提出された「Hybrid Landscape」という概念は、日本の都市景観の固有性のひとつを浮き彫りにし得る有効な手段として考えられる。

綿密な調査を土台とした知見の豊富さ、さらには「Hybrid Landscape」という概念の有効性などから、本論文は博士(工学)の学位請求論文として合格を認められる。