綠色空間助力城市發展

蘇州古城東南城門稱葑門，古時候葑門外是大片葑田和圩田，密布的水網交織穿城而過，出城的西北城門閶門經上塘河到大運河楓橋碼頭，再向西望是淺丘環繞，淺丘以西是太湖之濱。古城處在圩田水網系統之上，適應了農業生產、漕運和泄洪的需求。同時，遍布城內外的寺觀寶塔、園林和名勝錨固于圩田水網淺丘之上，形成山水人文意境與詩意城市。從拙政園東園過倚虹亭西望水線，可借景北寺塔，從北寺塔西眺可見西部諸山，如天平山、靈巖山、穹窿山等。拙政園中部遠香堂北臨的水面上有兩座島山野趣盎然，其中一島遍植柑橘隱喻太湖洞庭山，有亭為“待霜”。園林營造的城市山林表達出對自然山水的向往，是淺丘圩田水網本底上精神與美的升華。

隨著生產方式的變革，從農業向大規模工業化發展，人口迅速增長，城市密度加大，人地關系緊張，古代城市所依存的自然本底逐漸被蔓延的城市所占據，導致城市病的增加，也帶來了迷失自身特質的景觀和“千城一面”的城市風貌。

今天，綠色空間所承擔的生態使命，使其以更宏觀的視野介入城市，從城市結構布局到區域景觀體系，再到微觀上的街區更新，這一支撐系統可以改變土地利用和覆被變化，增強城市碳匯效益，提升雨洪調節等生態系統功能，協調山水林田湖草與城市人居環境的關系，更有效地整合自然資源，賦予城市更高質量的發展。加拿大多倫多市制定林冠蓋度達到40%目標，將林冠蓋度比例指標精細分配到綠地、居住用地等每類用地內，不同用地類型按不同比例權重規定，這樣保證了森林覆蓋到全市范圍，與城市空間廣泛融合。綠色空間還有利于促進城市空間功能復合和活化，構建“融合自然的城市更新”。北京實施的“留白增綠”就是結合城市更新計劃構建不同尺度的綠色空間，平安大街是一條尋找北京城文化積淀的歷史畫廊，最近的更新方式是在40 m寬的道路中間分車帶上增加綠化帶、種植大喬木，把失去的老城街道尺度找回來，增加口袋公園，與老城空間肌理更融洽。法國巴黎的香榭麗舍大街是世界上最繁華的街道之一，但近30年來，由于過度的旅游、商業、交通、污染和不透水鋪裝等原因，沿著大街漫步的行人中當地人僅占5%，它已經逐漸被巴黎人放棄，最新公布的改造計劃是使其成為一個“非凡的花園”，包括減少一半的車輛行駛空間，將街道變成人行區和綠地，種植更多樹木創造新的綠色空間，以提升空氣質量，讓街道變得更加親民、柔和，提升巴黎市民對城市的熱愛，成為未來新型城市生活模式的靈感之源。

相較于古代城市依托的農業水網基底，當代城市綠色空間成為城市發展的自然本底。雖然由于生產方式的變革，人文與美學所錨固的載體不同，但經過設計的園林景觀依然是自然本底上的文化制品。同古代城市一樣，都滿足了生產生活的客觀需求、人文的內涵、審美的秩序三方面的價值。意大利哲學家貝奈戴托·克羅齊（Benedetto Croce）說：“一切歷史都是當代史”，無論考量的時間跨度多么久遠，實際上，總是反映當前的情況并受其影響。隨著當代城市向信息時代轉變，生產方式又面臨新的變革，在未來城市場景中，綠色空間的價值又如何表達？隨著智能化的發展，市政交通等灰色基礎設施會逐步系統化、緊湊化，騰出的空間可形成新的綠色空間去織補城市，在便捷智慧的基礎上，核心還是營造一個健康、舒適、具有人文氣息的生活空間。讓城市綠色空間成為生態系統的本底，也是文化體系的孕育地，并符合時代審美，形成一個更健康的城市，才是綠色空間價值的最佳表達。

Green Space Empowering Urban Development

The southeast gate of the ancient city of Suzhou is named with “Feng”. In ancient times, outside the Fengmen Gate, there was a large area of “Fengtian” field (a kind of field land made by the siltation of Zizania roots and the sediments over time in the middle of the low land ponds) and polder fields, in-between a dense water network was interwoven through the city. Out of the city’s northwest gate Changmen Gate, the water would reach Fengqiao Pier of the Grand Canal through the Shangtanghe Canal. Looking west, the ancient city is surrounded by shallow hills and the west of the shallow hills is the shore of Taihu Lake. The ancient city is on top of the polder water network system, which has been adapted to the needs of agricultural production, water transport of grain to the capital and flood discharge. At the same time, the temples, pagodas,gardens and scenic spots all over the city and beyond are anchored on the shallow hills of the polder network, forming a city of landscape and humanistic mood of poetry. From the east garden of Humble Administrator’s Garden, one can look westward at the far-reaching water view after passing through the Yihong Pavilion, where can borrow the view of North Temple Pagoda, from which one can also see the mountains in the west, such as Tianping Mountain, Lingyan Mountain and Qionglong Mountain, etc. In the middle of Humble Administrator’s Garden, there are two islands on the water near the north of Yuanxiang Hall full of rustic charm. One of the islands is planted with citrus and has a pavilion called “Daishuang”, which is a metaphor for the Dongting Mountains in Taihu Lake. The urban landscape created by the garden expresses people’s deep yearning for natural landscape, and is the sublimation of spirit and beauty on the base of the water network of shallow hills and polder fields.

As the mode of production have been transformed from relying on agriculture to on large-scale industrialization, population grows rapidly, urban density intensifies, and the tension between people and land grows, the natural base on which ancient cities depended has gradually been taken over by sprawling cities, leading to an increase in urban diseases, a landscape that has lost its own character, and a “one-look-fits-all” urban feature.

In modern times, the ecological mission of green space is to intervene in cities with a more macroscopic vision. From the layout of urban structure to the regional landscape system, and further to the microscopic neighborhood renewal, this support system can transform land use and land cover change, enhance the benefits of urban carbon sink, improve rainfall and flood regulation and other ecosystem functions, coordinate the relationship between mountains, rivers, forests, farmlands, lakes, grasslands and urban habitat, integrate natural resources more effectively, and empower cities with high quality development. Toronto, Canada, has set a target of 40% forest canopy cover, and the proportional index of forest canopy cover is finely allocated to each type of land, such as green space and residential land. With different proportional weights specified for different land types, this move ensures that the forest covers the whole city and is widely integrated with urban space.Green space is also conducive to the promotion of urban space function compounding and activation, and the construction of“urban renewal integrating nature”. The initiative of “leaving blank and increase greenery” (leaving corresponding blank areas in urban planning to prepare space for future development, and expanding green ecological space and increase the ecological capacity of the city) implemented in Beijing is to build green spaces of different scales in conjunction with urban renewal plans. Ping’an Avenue is a historical gallery in search of the cultural deposits of Beijing,which was recently renewed by adding green belts and planting large trees in the middle of the 40-meter-wide road divider to bring back the lost scale of the old city streets and adding pocket parks to match the spatial texture of the old city. The park will be more harmonious with the spatial texture of the old city. The Champs-élysées in Paris, France is one of the busiest streets in the world. But in the last 30 years, due to excessive tourism, business,traffic, pollution and impervious pavement, locals make up only 5%of the people strolling along the avenue, and it has been gradually abandoned by Parisians. The latest renewal plan is to turn it into an “extraordinary garden”. This initiative includes reducing the traffic space by half, turning the streets into pedestrian zones and green spaces, and planting more trees to create new green spaces to improve air quality and make the streets more accessible and gentle,which will enhance Parisians’ love for the city and become a source of inspiration for a new urban living model in the future.

In contrast to the agricultural water network on which the ancient city was based, the contemporary urban green space has become the natural base for urban development. Although the humanities and aesthetics are anchored by different carriers due to changes in production methods, the designed landscape is still a cultural artifact on a natural base. Like ancient cities, they all meet the objective needs of productive life, the connotation of humanism, and the value of aesthetic order in three ways.The Italian philosopher Benedetto Croce said, “All history is contemporary history”, and no matter how long the time span is under consideration, in fact, it always reflects and is influenced by the current situation. As contemporary cities transform into digital ones under the influence of the information age and face new changes in production methods, how will the value of green space be expressed in the future urban scenario? As intelligence develops,the gray infrastructure such as municipal transportation will be gradually systematized and compacted, and the vacated space can form a new green space to weave the city. Following the basic principle of shaping a convenient, smart city, the core is still to create a healthy, comfortable and humanistic living space. The best expression of the value of green space is to let the urban green space become the background of the ecosystem and the breeding ground of the cultural system, and to conform to the aesthetics of the times to build a healthier city.

Editor-in-Chief: Professor ZHENG Xi

January 22, 2021