城市藍(lán)綠空間系統(tǒng)

藍(lán)綠空間系統(tǒng)反映了自然的演替和時空發(fā)展中人類對城市與自然的不斷干預(yù)。藍(lán)綠空間保證了把自然帶到城市，這對人們來說非常重要。因為無論身在何處，人都要與自然建立聯(lián)系，確保生活質(zhì)量，以滿足人類的基本需求。

奧姆斯特德（Olmsted）在波士頓的翡翠項鏈設(shè)計中，梳理了泥濘的河流系統(tǒng)，為水、沼澤地和低地提供了空間，這是一個適應(yīng)氣候變化的范式。而后，在規(guī)劃中央公園時，奧姆斯特德和沃克斯（Vaux）檢查了曼哈頓島的地質(zhì)層，沒有對原生景觀進(jìn)行過多改造，只增加了道路、水庫和湖泊，而公園外，曼哈頓原始地貌則被夷為平地，為城市網(wǎng)格讓路。自19世紀(jì)末以來的發(fā)展，奧姆斯特德推動了城市公園與綠地系統(tǒng)建設(shè)，綠化了城市。隨著工業(yè)化和城市化的快速發(fā)展，伊恩·麥克哈格（Ian Lennox McHarg）認(rèn)為土地上開放空間的分布必須要反映自然的演進(jìn)過程，這一點對任何大都市地區(qū)來說，不管其位置如何，都是適用的，并倡導(dǎo)在區(qū)域范圍內(nèi)結(jié)合自然進(jìn)行設(shè)計。隨著后工業(yè)化以及城市更新的推進(jìn)，科納（James Corner）強調(diào)了對景觀過程的管理，要建立對藍(lán)綠空間長期適應(yīng)性發(fā)展戰(zhàn)略。

事實上，由綠色空間和水域空間組成的藍(lán)綠空間系統(tǒng)作為一個相互交織的整體，不僅成為多尺度下生態(tài)基礎(chǔ)設(shè)施網(wǎng)絡(luò)構(gòu)建的基礎(chǔ)，而且是促進(jìn)城市自然體系發(fā)展，提高城市韌性與增強生命力的重要保障。在這一基礎(chǔ)上，中、西方對于藍(lán)綠空間系統(tǒng)的認(rèn)知，有著十分一致的看法，那就是對“結(jié)構(gòu)”的發(fā)現(xiàn)、感知、把握和應(yīng)用。這種結(jié)構(gòu)存在于每個人的身邊，特別是從飛機上鳥瞰某個城市時，熟悉的山水關(guān)系和大尺度的藍(lán)綠結(jié)構(gòu)便會印刻在我們的腦海中，例如群山中的杭州西湖景觀、河網(wǎng)密布的紐約哈德遜河谷景觀、阿爾卑斯山腳下慕尼黑伊薩河谷景觀和倫敦泰晤士河及其平原景觀。

人類對這種空間圖式關(guān)系并不陌生，在不同文化背景下，人們也對這一關(guān)系有著各自獨特的理解。中國人善于在人工聚落中營建自然系統(tǒng)，創(chuàng)造詩意的棲居環(huán)境?！皩び奶絼佟奔耐辛酥袊藢ι剿南蛲吞剿鳎叭收邩飞?，智者樂水”體現(xiàn)了中國山水文化中物質(zhì)性與精神性的高度統(tǒng)一。而在現(xiàn)代社會中，隨著城市空間的開發(fā)與建設(shè)，如何把對山水體系的再塑造融合到城市重要的藍(lán)綠空間系統(tǒng)中，已成為中國風(fēng)景園林師面臨的巨大挑戰(zhàn)和理應(yīng)承擔(dān)的重要任務(wù)。同樣，西方人也認(rèn)可這種動態(tài)的自然與人工體系，歐洲學(xué)者將這一連貫、完整的城市系統(tǒng)看作一種藍(lán)綠空間相互融合的巨大“多孔結(jié)構(gòu)”，它空間形態(tài)多樣、組織方式靈活，具有明顯的空間滲透性、包容性和結(jié)構(gòu)識別性。英國風(fēng)景園林師湯姆·特納（Tom Turner）認(rèn)為無論從人的心理和身體，城市和鄉(xiāng)村，還是空間交織和分離的角度分析，未來的城市將會是一系列無限的景觀，這與建筑師克里斯托弗·亞歷山大（Christopher Alexander）理解的“城市不是一棵樹，它是一種景觀”觀點相似，不斷發(fā)展和演替的藍(lán)綠空間系統(tǒng)是最能體現(xiàn)城市空間開放性、動態(tài)性、文化性和生態(tài)性的景觀網(wǎng)絡(luò)。

在圍繞藍(lán)綠空間的研究中，可以看出它們與大都市的發(fā)展形式和開放空間的分布形式有著最密切的關(guān)系。麥克哈格證明了對藍(lán)綠空間系統(tǒng)的建設(shè)，其問題不在于絕對面積的多少，而在于如何分布。作為能夠充分反映自然演進(jìn)過程的復(fù)雜系統(tǒng)，藍(lán)綠空間相互耦合形成的綜合體，應(yīng)具有整體性特征，必須在規(guī)劃中進(jìn)行理性、綜合的考慮，深刻遵循自然的規(guī)律，以系統(tǒng)觀的生態(tài)手段應(yīng)對自然災(zāi)害，構(gòu)建更加韌性和具有生命力的藍(lán)綠空間系統(tǒng)，讓整個城市的資源調(diào)配在這個系統(tǒng)中高效地運轉(zhuǎn)。在國土空間范疇下，它是每一個風(fēng)景園林師都應(yīng)面對和處理的復(fù)雜系統(tǒng)。

Urban Blue-Green Space System

The blue-green space system maps continuous human interventions in cities and the nature during the natural evolution and spatiotemporal development. The blue-green space ensures the availability of nature to cities, which is critical for human beings, because it is important to be able to establish connection with the nature and guarantee the quality of life, so as to meet basic needs of humans, no matter where they reside.

In the design of Boston’s Emerald Necklace, Olmsted analyzed muddy river systems to provide space for water, marshes and lowlands, formulating a paradigm for adapting to climate change. And afterwards, when planning the Central Park, Olmsted and Vaux examined the geological layers of Manhattan Island and decided not to modify its native landscape too much. Rather, they added only some roads, reservoirs and lakes. While outside the park, the original Manhattan landscape was razed to make way for the urban grids. In the development since the late 19th century,Olmsted has promoted the creation of urban systems for parks and green spaces and greened the cities. Ian Lennox McHarg maintains that with rapid industrialization and urbanization, the distribution of open space on the land shall echo the evolution of nature. This idea holds true for any metropolitan area, regardless of its location. And he also advocated designs in combination with the nature on a regional scale. With the advancement in postindustrialization and urban renewal, James Corner emphasizes the management of landscape processes, purposed to frame a longterm adaptive development strategy for the blue-green space.

In fact, composed of green space and water space, the bluegreen space system is an interwoven entity, not only becoming a foundation for the construction of ecological infrastructure networks at multiple scales, but also forming an important guarantee to facilitate the development of urban natural systems and boost the resilience and vitality of cities. On this basis,Eastern and Western scholars reach a very consistent view on the cognition of the blue-green space system—the discovery,perception, understanding and application of “structures,” which exist around everyone. Especially when we get a bird’s eye view of a city from an airplane, the familiar landscape relationship and large-scale blue-green structures would be imprinted in our mind, for example: the West Lake landscape in Hangzhou amid mountains; the Hudson River Valley landscape in New York, with a dense network of rivers; the Isar Valley landscape in Munich at the foot of the Alps; and the Thames River and its plains landscape in London.

Humans are no strangers to such spatial patterning relationship, of which people hold their own unique understanding under different cultural contexts. Chinese are good at constructing natural systems in artificial settlements, so as to create poetic living environment. “Search for seclusion and beautiful scenery” embodies the Chinese people’s aspiration and exploration of landscapes; and “Wise men enjoy water while benevolent ones enjoy mountains” reflects the high degree of unity between materiality and spirituality in Chinese landscape cultures. In modern societies, however, with the development and construction of urban space, it has become a great challenge and surely an important task for Chinese landscape architects to reshape and integrate the landscape system into the significant blue-green space system in cities. Similarly, Westerners also recognize this kind of dynamic natural-artificial system. In fact,European scholars regard such coherent and holistic urban system as a huge “porous structure”, with blue and green spaces converging with each other. This structure is spatially diverse,featuring flexible organizational forms as well as remarkable spatial permeability, inclusiveness and structural identifiability.According to British landscape architect Tom Turner, the future city will be an infinite series of landscapes, whether analyzed from the perspective of human psychology and body, or from that of urban and rural areas, or from that of spatial interweaving and separation. This argument is similar to a viewpoint held by architect Christopher Alexander: “A City is not a tree, it is a landscape.” With this understanding, the constantly developing and evolving blue-green space system becomes a landscape network that can best demonstrate the openness, dynamism,culture and ecology of urban space.

The studies related to the blue-green space are most closely associated with the forms of metropolitan development and the distribution of open spaces. Ian Lennox McHarg has demonstrated that the problem with the construction of the bluegreen space system lies not in the absolute amount of areas, but on how they are distributed. As a complex system that can fully showcase the natural evolution process, the blue and green spaces couple with each other to form a synthesis. Therefore, its holistic characteristics shall be weighed in a rational and comprehensive manner in the planning process by profoundly following the laws of nature, so as to respond to natural disasters with ecological means of systematic views and build up a more resilient and vital blue-green space system. In this system, the entire resource deployment of a city can functioning properly in high efficiency.It is a complicated system that every landscape architect has to face and deal with in the domain of territorial land.

Editor-in-Chief: Professor ZHENG Xi

December 3, 2022