著：（德）費(fèi)迪南德·路德維希 （德）丹尼爾·舍恩 譯：李夢(mèng)一欣

0 引言

吉爾斯·克萊門特發(fā)表生態(tài)宣言《行星花園》已有20余年，他在宣言中呼吁我們應(yīng)像園丁耕種和照料每一片土地一樣對(duì)待和關(guān)愛我們的地球。對(duì)此，克萊門特認(rèn)為有必要與花園自然生態(tài)系統(tǒng)一起行動(dòng)與合作，以關(guān)注生命的復(fù)雜性和多樣性[1]。如果我們看看今天的城市，通常會(huì)發(fā)現(xiàn)完全相反的情況：建筑和技術(shù)基礎(chǔ)設(shè)施占據(jù)著主導(dǎo)地位，其實(shí)現(xiàn)方式通常依照全球標(biāo)準(zhǔn)，既沒有參考當(dāng)?shù)厣鷳B(tài)系統(tǒng)所處環(huán)境，又完全忽視其景觀條件。理想情況下，城市與公園系統(tǒng)相互交織，但實(shí)際中綠色空間經(jīng)常成為剩余物，以至于幾乎沒有為樹木種植或高質(zhì)量花園留有空間。倘若有人認(rèn)真思考吉爾斯·克萊門特的想法，那么建筑物也必須被視為“行星花園”中不可或缺的組成部分，而非一種異形物。因此，建筑的開發(fā)方式應(yīng)該是技術(shù)和生命系統(tǒng)的共生，而活體植物建筑（德語：Baubotanik）方法能夠?qū)⒔ㄖ蜆淠竞铣梢粋€(gè)新的統(tǒng)一體以滿足這一需求。

“Baubotanik”一詞描述了一種建筑形式，其結(jié)構(gòu)的創(chuàng)建是通過技術(shù)連接和植物生長之間的相互作用，通過控制樹木或某些部分的生長將其互相結(jié)合，并以這樣的方式與非生命組件連接起來，合成一個(gè)植物–技術(shù)實(shí)體[2-3]。利用樹干、樹枝和樹根，將樹木直接、切實(shí)地作為“有生命的建筑材料”。它們的生長形態(tài)可以通過相對(duì)簡單的技術(shù)手段實(shí)施較高程度的控制，繼而轉(zhuǎn)化為具有不同建筑內(nèi)涵的結(jié)構(gòu)。在此方面，樹木被視為一種建造元素，一種“有生命的半成品”。然而，同時(shí)它也必須被理解并視為一個(gè)與環(huán)境不斷交換的生物體。

歷史上著名的生命建筑案例不僅有德國的“舞動(dòng)的菩提樹”[4-6]、印度梅加拉亞邦的活樹根橋[7-9]，還有諸如樹籬裝置[10]這樣的簡單鄉(xiāng)村實(shí)踐。早在20世紀(jì)70—80年代，建筑師弗雷·奧托和他的團(tuán)隊(duì)[11-12]已在久負(fù)盛名的德國斯圖加特大學(xué)輕型建造研究所研究并探討了這種植物建造方法。在這一背景下，建筑師魯?shù)婪颉ざ嗉{赫發(fā)展了他的“生物結(jié)構(gòu)”[13]理念，受其啟發(fā)產(chǎn)生了一系列“柔和的結(jié)構(gòu)”，其中包含柳木制的建筑穹頂和一些活體植物結(jié)構(gòu)[14-15]。此外，工程師洛薩·韋索利提出了新學(xué)科樹木靜力學(xué)的首要原則，如今它與其他方法，如可視化樹木評(píng)估（VTA）[16]，共同促進(jìn)了全球范圍內(nèi)的樹木承載力與穩(wěn)定性調(diào)查。近幾十年來，世界各地的建筑師和設(shè)計(jì)師都采用了利用樹木創(chuàng)造生命建筑的想法以解決城市生態(tài)、可持續(xù)設(shè)計(jì)和氣候適應(yīng)性變化等方面的諸多問題[17-18]。

在這些傳統(tǒng)的基礎(chǔ)上，植物建造研究小組通過實(shí)證研究、多個(gè)實(shí)驗(yàn)性結(jié)構(gòu)以及對(duì)設(shè)計(jì)和工程工具的開發(fā)，促進(jìn)了一直以來尚待完善的相關(guān)理論與實(shí)踐研究基礎(chǔ)。通過這種方式，旨在生成設(shè)計(jì)知識(shí)，使生命建筑的概念、規(guī)劃和實(shí)現(xiàn)成為可能，并適用于更廣范圍[2,19-20]。筆者將根據(jù)項(xiàng)目實(shí)例闡釋植物建造的概念性框架，以展望面向未來的機(jī)遇和挑戰(zhàn)。

1 與樹共同設(shè)計(jì)

在Baubotanik中，建筑設(shè)計(jì)師成為一名合作者，就像園丁一樣，與一棵樹一起創(chuàng)造出一種結(jié)構(gòu)，它永遠(yuǎn)不會(huì)被建造“完成”，即使這一結(jié)構(gòu)遲早會(huì)達(dá)到預(yù)期的發(fā)展階段。未來的實(shí)際狀況在很大程度上取決于那些無法計(jì)劃的情況和因素，雖可被預(yù)測(cè)，但僅限于十分籠統(tǒng)的陳述。然而越是試圖展望未來，愿景就會(huì)變得越模糊。對(duì)經(jīng)典建筑學(xué)而言，它的設(shè)計(jì)總是與自然相互對(duì)立，并盡可能實(shí)現(xiàn)永久性建造，這顯然是自欺欺人的：一個(gè)建筑，無論尺寸還是尺度都無法精確地被規(guī)劃出來[21]。而生命建筑的外觀會(huì)隨著季節(jié)的變化而變化，尤其是在溫帶氣候區(qū)：秋天先變得五顏六色，冬天落葉后顯得光禿禿的，可能看起來有點(diǎn)粗糙，春天又發(fā)芽、開花，夏季郁郁蔥蔥，幾乎無法被認(rèn)出是一座建筑。

Baubotanik人行橋（圖1）是展現(xiàn)上文所述建筑特性的一個(gè)恰當(dāng)例證。2005年，Baubotanik研究小組的成員們?cè)诳邓固勾暮浇囊粋€(gè)曾是沼澤的區(qū)域?qū)崿F(xiàn)了這一具有實(shí)驗(yàn)性和示范性的結(jié)構(gòu)。它證明了Baubotanik項(xiàng)目如何柔和地融入現(xiàn)有（文化）景觀的風(fēng)景中，以及如何謹(jǐn)慎地與脆弱的生態(tài)系統(tǒng)產(chǎn)生互動(dòng)。這一項(xiàng)目為Baubotanik技術(shù)在自然保護(hù)地和景觀保護(hù)區(qū)中的應(yīng)用開辟了諸多可能性，總體來說，無論在哪里建筑都能在視覺上與景觀相融合[19]。

1 Baubotanik人行橋展示了生命建筑如何成為生態(tài)系統(tǒng)中不可或缺的組成部分以及人類如何感知所營造的樹冠空間The Baubotanik Footbridge exemplifies how living architecture can become an integral part of an ecosystem and how humans can perceive the space of the constructed canopy

與試圖最小化生態(tài)系統(tǒng)干預(yù)的純技術(shù)性生態(tài)建設(shè)方法不同，Baubotanik項(xiàng)目始終通過有活力的過程與所處環(huán)境產(chǎn)生積極交流，在其自身發(fā)展中改變環(huán)境的同時(shí)受其影響：它們根據(jù)光照和風(fēng)力條件改變自身形狀，并對(duì)干旱、高溫或霜凍做出反應(yīng)。風(fēng)可能會(huì)彎曲或折斷樹枝，冰雹可能會(huì)損壞樹皮，然而在這些傷口重新愈合后仍會(huì)在它們身上留下永久可見的疤痕。這使得Baubotanik結(jié)構(gòu)成為一種“傳記”，可以讓人直接感知和“閱讀”多年以來它所形成的獨(dú)特個(gè)性。那些不斷進(jìn)化的獨(dú)特性可以解釋為一種與個(gè)體間產(chǎn)生的紐帶以及人們對(duì)古樹的厚愛與欣賞。我們有充分的理由相信，當(dāng)有生命的樹成為建筑結(jié)構(gòu)的基本組成部分時(shí)，這種情感關(guān)系便會(huì)轉(zhuǎn)移到建筑之中。

然而，我們喜愛與珍視的樹木往往不屬于純凈的、未受破壞的自然，而是通過育種、種植和修剪創(chuàng)造出的“文化產(chǎn)品”。這一點(diǎn)在果園的例子中十分明顯，它看起來是樹木自身生長與人工排列和控制相互作用的結(jié)果。Baubotanik項(xiàng)目的特點(diǎn)也通過這種十分有趣的關(guān)系呈現(xiàn)出來，但在種植和技術(shù)建造要素相互關(guān)聯(lián)的節(jié)點(diǎn)上，其人工干預(yù)程度通常更高，可見性更強(qiáng)，且更易于掌握。

在這些節(jié)點(diǎn)中，技術(shù)組件蔓生并與有生命的樹木合為一體，積極層面上，人們可以看到生物與技術(shù)成功地相互融合，其生長過程以形式上的契合為實(shí)現(xiàn)方式，而非只是單獨(dú)的技術(shù)連接。消極層面上，人們卻從中發(fā)現(xiàn)了對(duì)自然的濫用，植物被冰冷的鋼管以強(qiáng)大的力量穿透，通過這種矛盾心理，Baubotanik項(xiàng)目鼓勵(lì)人們思考人類對(duì)待自然的方式，從而推動(dòng)關(guān)于社會(huì)中自然與技術(shù)關(guān)系的討論。

2 用心和時(shí)間進(jìn)行設(shè)計(jì)

吉爾斯·克萊門特認(rèn)為“行星花園”所需要的持久關(guān)注同樣也為生命建筑賦予了意義，這些建筑因?yàn)槠錁?gòu)造所具備的生命屬性，始終需要得到悉心的關(guān)注和維護(hù)。其中，維護(hù)的概念必須不斷被調(diào)整以適應(yīng)實(shí)際發(fā)展?fàn)顩r，這在風(fēng)景園林和園藝專業(yè)中并非新鮮事，但在建筑施工建造中并不常見。這就是為什么我們可以將Baubotanik和吉爾斯·克萊門特的觀點(diǎn)描述為一種園藝形式的建筑并始終從過程的角度去思考。在這一過程中，懷揣等待和秉持耐心與富有遠(yuǎn)見和滿懷期待地行動(dòng)同等重要。實(shí)際上，風(fēng)景園林甚至城市規(guī)劃專業(yè)都熟知這些內(nèi)容，但它們卻極少成為設(shè)計(jì)概念的明確組成部分[22-23]。

事實(shí)上，樹木通常需要幾十年的時(shí)間才能達(dá)到豐盈的尺寸，并充分滿足人們對(duì)它的期望。與此同時(shí)，城市可能發(fā)生巨大的變化。因此，在19世紀(jì)00年代歐洲城市中種下的一棵樹，在經(jīng)歷了19世紀(jì)的城市擴(kuò)張和第二次世界大戰(zhàn)的破壞，以及20世紀(jì)以居住區(qū)和園區(qū)為改造內(nèi)容的城市重建和擴(kuò)張后，這棵樹很有可能仍處于生命的黃金時(shí)期（圖2）。未來總是難以預(yù)測(cè)的，毫無疑問，我們只能在有限的范圍內(nèi)預(yù)測(cè)這些動(dòng)態(tài)。盡管如此，我們應(yīng)敢于嘗試將樹木生長過程與城市、社會(huì)和生態(tài)變化聯(lián)系起來，這意味著我們必須將任何形式的生命建筑理解為一種開放的、與未來之間的相互交流。

2 將樹齡200年的植物與歐洲示范城市200年的發(fā)展相對(duì)比，Baubotanik概念和技術(shù)需協(xié)調(diào)不同時(shí)期的發(fā)展Exemplary illustration of 200 years of tree growth in comparison with 200 years of urban development of an exemplary European city. The very different temporal developments need to be harmonized in Baubotanik concepts and techniques

全球人口的快速增長以及同樣迅速的城市化進(jìn)程正使得城市地區(qū)成為緊迫的生態(tài)與社會(huì)問題的焦點(diǎn)。在許多地方，氣候變化早已不再是未來的噩夢(mèng)，而是成了現(xiàn)實(shí)，人們每天都可以在溫度過高的街道上感知到這一變化。樹木擁有巨大的、涼爽且遮陰的樹冠，可以為解決氣候變化問題、提高福祉和促進(jìn)人類健康作出有價(jià)值的貢獻(xiàn)。然而，正如人們已經(jīng)看到的，樹木需要幾十年才能發(fā)育成形并充分發(fā)揮其氣候效應(yīng)和對(duì)人類健康產(chǎn)生益處。如果Baubotanik正為尋求回答此問題做出相關(guān)努力，并在多層建筑的尺度中以有生命的結(jié)構(gòu)改善城市環(huán)境，那么解決方案就必須在此時(shí)此地被呈現(xiàn)——而不是在未來某個(gè)不確定的時(shí)刻。以Baubotanik塔（圖3）和梧桐樹立方體（圖4）為例，Baubotanik研究小組的測(cè)試和實(shí)驗(yàn)性建筑的初步發(fā)現(xiàn)，證明了可以通過新開發(fā)的植物嫁接技術(shù)直接在生長完好的樹木上建造生命建筑。這一技術(shù)基于這樣一個(gè)事實(shí)，即樹木有能力在同一地點(diǎn)或其他地方通過產(chǎn)生新的植物組織來補(bǔ)償其損失。如果幾株植物被嫁接并因此合并為一個(gè)有機(jī)體，那么之前的個(gè)體便不再需要它們各自的生物體部分。這意味著根或葉，甚至兩者都可以被移除，其前提是融合為一個(gè)整體的結(jié)構(gòu)能夠補(bǔ)償這些植物組織的損失。植物嫁接技術(shù)利用幼年植株，將其排列在空間上方，彼此相鄰并以這樣的方式連接起來，使它們?nèi)诤蠟橐粋€(gè)網(wǎng)狀植物結(jié)構(gòu)。只有位置最低的植物被種植在地下，所有其他植物都被種在帶有自動(dòng)化系統(tǒng)的特殊容器中，該系統(tǒng)不斷提供水和養(yǎng)分使它們能夠生長。隨著網(wǎng)絡(luò)的發(fā)展，埋在地下的根系擁有更多的空間來開發(fā)額外的資源，相比放在容器中的根生長得更旺盛。一旦嫁接形成，水和養(yǎng)分就可以通過人工創(chuàng)造的植物結(jié)構(gòu)從地下的根部運(yùn)輸?shù)阶铐敹说娜~子，而容器中植物的根就會(huì)被淘汰。逐步地，那些高層根系可以被切斷，自動(dòng)供水系統(tǒng)也可以相應(yīng)被移除，最終，生命結(jié)構(gòu)變得自給自足。同時(shí)，植物結(jié)構(gòu)更加堅(jiān)固，甚至可以通過根莖的次生生長實(shí)現(xiàn)自主供給，而最初用來支撐容器和幼苗的腳手架則可以被移除[3,20,24]。

3 Baubotanik塔是第一個(gè)應(yīng)用植物嫁接技術(shù)在生長完好的樹木上直接創(chuàng)造出的實(shí)驗(yàn)性生命結(jié)構(gòu)The Baubotanik Tower is the first experimental structure that applies the plant addition technique to create living structures immediately in the dimension of a fully grown tree

4 2012年起，預(yù)計(jì)未來20年梧桐樹立方體的發(fā)展（納戈?duì)柕?，德國）Expected future development of Plane Tree Cube (Nagold,Germany) from 2012 over the coming ca. 20 years

3 展望

以這種方式，Baubotanik生成的綠色結(jié)構(gòu)作為建成環(huán)境的組成部分，這些結(jié)構(gòu)在很短時(shí)間內(nèi)即可被使用，并提供數(shù)十年樹齡植物所具有的生態(tài)品質(zhì)。特別是微氣候效應(yīng)，例如通過蒸發(fā)使空氣涼爽并凈化細(xì)粉塵。生命建筑辦公室（OLA）在柏林設(shè)計(jì)的“未來之家”就是利用了植物所產(chǎn)生的生態(tài)效應(yīng)開發(fā)了一棟建筑，該建筑在一定程度上通過樹木進(jìn)行空氣冷卻與調(diào)節(jié)，同時(shí)對(duì)建筑周圍的微氣候產(chǎn)生了積極的影響（圖5）。

5 德國柏林“未來之家”提案，該設(shè)計(jì)的外立面體現(xiàn)了未來的不確定性，同時(shí)建筑的氣候性概念也成為其組成部分Proposal for the “House of Future” in Berlin, Germany. The design reflects the uncertainty of the future in its fa?ade that at the same time is an integral part of the climatic concept of the building

大量研究證明，這種效應(yīng)對(duì)人們的健康和幸福具有決定性影響。例如，卡達(dá)內(nèi)等[25]發(fā)現(xiàn)在同等年齡和收入的社區(qū)人群中，住在擁有較多行道樹街區(qū)的居民患心血管和代謝類疾病的概率明顯低于住在樹木較少街區(qū)的居民。如果人們將自己對(duì)生活質(zhì)量的主觀評(píng)價(jià)與人口年齡和收入結(jié)構(gòu)進(jìn)行比較、評(píng)價(jià)與關(guān)聯(lián)，就會(huì)發(fā)現(xiàn)與住在樹木繁茂街道上的居民相比，住在樹木貧瘠街道上的那些年輕了7歲或年收入至少為1萬美元（人民幣約64 800元，2021年8月17日匯率為6.48）的居民，對(duì)生活質(zhì)量的評(píng)價(jià)幾乎同樣高。它不僅證明了居民個(gè)體所產(chǎn)生的附加值，而且記錄了城市樹木的整體經(jīng)濟(jì)效益。如果Baubotanik能夠成功地創(chuàng)造出不同結(jié)構(gòu)，并展現(xiàn)出對(duì)健康、心理和社會(huì)經(jīng)濟(jì)的諸多影響，那么在建造和維護(hù)方面的努力將是完全合理的。在此基礎(chǔ)上，整個(gè)城市——不僅僅是人口稀少的郊區(qū)——可以被視作促進(jìn)人類健康的樹木花園，它與人類居民共同進(jìn)化，體現(xiàn)了吉爾斯·克萊門特所想象的更大的“行星花園”的基本組成。

圖片來源：

圖1 ?Cira Moro，設(shè)計(jì)：F. Ludwig、O. Storz、C.Hackenbracht；圖2、4～5 ?生命建筑辦公室；圖3?F.Ludwig，設(shè)計(jì)：F. Ludwig、C. Hackenbracht。

（編輯/劉昱霏）

Growing Architecture for the Planetary Garden:Position Paper on Living Architecture in the Context of Gardens and Healthy Environment

Authors: (DEU) Ferdinand Ludwig, (DEU) Daniel Sch?nle Translator: LI Mengyixin

0 Introduction

It is now more than 20 years since Gilles Clement published his ecological manifestoThe Planetary Garden, in which he urged that we should treat and care for the planet entrusted to us as carefully as a gardener cultivates and cares for the piece of land entrusted to him. Therefor it is necessary to act and work with, rather than against, the natural ecosystem of the garden to care of its complexity and diversity of life, Clement continues[1]. If we look at our cities today, however,we usually see exactly the opposite: buildings and technical infrastructures dominate the scene,often realized according to global standards and without reference to the conditions of local ecosystems, completely ignoring the conditions of the landscape. When things go well, these cities are interwoven with a system of parks, but often green spaces are rather leftovers that hardly allow space for planting trees or designing high-quality gardens. If one takes Gilles Clement seriously in this regard, also buildings must be thought of as integral components and not as alien bodies of the planetary garden. Therefor they should be developed in such a way that a symbiosis of technical and biological systems is created. The approach of Baubotanik to merge buildings and trees into a new unity could meet this demand.

The term Baubotanik describes a form of architecture in which structures are created through the interaction of technical joining and plant growth by manipulating the growth of trees or their parts, joining them with each other and connecting them with non-living components in such a way that they merge into a botanicaltechnical entity[2-3]. With their trunks, branches and roots, trees are directly tangible as “l(fā)iving building materials”. Their growth form can be manipulated to a relatively high degree with comparatively simple technical means to be transformed into different architecturally meaningful structures. In this regard, the tree is seen as a building element,as a “l(fā)iving semi-finished product”. Nevertheless, it must be understood as a biological entity that is in constant exchange with its environment and needs to be treated accordingly.

Historic examples of living architecture range from German “Tanzlinden”[4-6]and Meghalaya’s living root bridges[7-9]to simple rural practices such as hedge laying[10]. The research into this approach takes up aspects that were already being discussed at the legendary Institute for Lightweight Construction (IL, University of Stuttgart,Germany) in the 1970s and 80s by Frei Otto and his team[11-12]. In this context the architect Rudolph Doernach developed his vision of “biotecture”[13]which inspired, among others, the group “Sanfte Strukturen” (“gentle structures”) with their willow domes and other living structures[14-15]. Furthermore the engineer Lothar Wessolly developed the first principles of a new discipline, tree statics, which today together with other approaches like visual tree assessment (VTA)[16]contributes worldwide to investigating the load-bearing capacity and stability of trees. In recent decades the idea of creating living architecture with trees has been adapted by architects and designers worldwide to address aspects of urban ecology, sustainable design and climate change adaptation[17-18].

Building on these traditions, the work of research group Baubotanik develops the theoretical and practical foundations that have been lacking up to now by means of empirical studies, experimental structures and the development of design and engineering tools. In this way, the research aims to generate design knowledge that enables the conception, planning and realization of architecture with living trees and makes them applicable on a broader scale[2,19-20]. Below, the conceptual framework of Baubotanik is presented on the basis of project examples in order to provide an outlook on future chances and challenges.

1 Co-designing with Trees

In Baubotanik, the architect becomes a codesigner who – like a gardener – creates a structure together with a tree. It will never be “finished”,even if the desired stages of development are reached sooner or later. How it will actually look in the future depends on circumstances and factors that cannot be planned for to a great extent.Forecasts are certainly possible, but they are limited to rather general statements. And the further one tries to look into the future, the blurrier the picture becomes. For classical architecture, which in principle is always designed in contrast to nature and constructed as something as permanent as possible, this is an imposition: Neither the size nor the proportions of a building can be determined exactly by the planner[21]. And especially in the temperate climate zones, its appearance can also change with the seasons: In autumn it first becomes colorful and then loses its leaves, in winter it is bare and may appear gnarly, in spring it sprouts again,perhaps blossoms, and in summer it is densely foliated, possibly barely recognizable as a building.

These attributes are exemplified by the Baubotanik Footbridge (Fig. 1), which was realized back in 2005 as an experimental and demonstration structure by members of research group Baubotanik in a former swamp area near Lake Constance. It also demonstrates how Baubotanik projects can be integrated gently into the scenery of an existing (cultural) landscape and how sensitively they interact with fragile ecosystems.This opens up possibilities for application in nature reserves and landscape conservation areas and, in general, wherever buildings are to visually merge with the landscape[19].

Unlike purely technically minded ecological construction methods, which try to minimize the intervention in an ecosystem, Baubotanik projects are always in active exchange with their environment through their vital processes, change it and are shaped by it in their development: they adapt their shape to the light and wind conditions,react to drought, heat or frost. Wind may bend or break a branch or a hailstorm may damage the bark in such a way that even after successful wound healing, permanently visible scars remain.This makes the “biography” of a Baubotanik structure directly perceivable and readable – over the years, it develops a unique, individual character.The almost personal bond and the enormous appreciation that many people have for old trees can be explained by this evolved uniqueness. And we have good reason to believe that this emotional relationship is transferred to architecture when living trees become an elementary component of an architectural structure.

However, the trees we love and appreciate are often not pure, untouched nature, but rather cultural products that have been created through breeding, planting and pruning. This becomes clear, for example, in the case of orchards, whose appearance results from the interplay of the momentum of growing trees and their artificial arrangement and manipulation. Baubotanik projects are also characterized by this highly intriguing relationship, but the share of the artificial is often even higher, clearly visible and literally graspable at the points where the plant and technical construction elements are connected with each other.

In these joints, where technical components are overgrown and incorporated by the living tree,one can see the successful symbiosis of nature and technology, in which growth processes are directed in such a way that a form fit is achieved that would not be possible through technical joining alone. Or one can see in it an abuse of nature, in which the plant is penetrated by a cold steel tube in an act of violence. Through this ambivalence, Baubotanik projects encourage us to think about our treatment of nature and thus contribute to a debate about the relation of nature and technology in society.

2 Designing with Care and Time

The permanent attention that Gilles Clement demands for the “planetary garden”also characterizes Baubotanik buildings, which require a certain amount of mindfulness and care throughout their lifetime. Maintenance concepts have to be developed and continuously adapted to the actual development. This is nothing new in landscape architecture and gardening, but it is certainly the case in building construction. This is why we can characterize Baubotanik with Gilles Clement as a horticultural form of architecture that must always be thought of in terms of processes.Waiting and patience are as much a part of it as being far-sighted and acting with anticipation.Landscape architecture and even urban planning are actually familiar with these aspects, but they are still far too rarely an explicit component of the design concept[22-23].

Indeed, it often takes decades for trees to reach their full size and to fully meet the expectations placed on them. In the same time,cities can change dramatically. Thus, a tree planted in the context of a European city in the 1800s – which may still be in prime of life – has experienced the urban expansions of the 19th century as well as the destruction of the World War II, the reconstruction and expansion of the city through housing estates and business parks in the 20th century (Fig. 2). Since the future is always speculative it is needless to say that we can only predict these dynamics to a limited extent.However, we should dare trying to relate tree growth processes, that are also only predictable to a limited extent, to urban, social and ecological changes. This means that we have to understand any form of living architecture as an open invitation to the future.

The rapid global population growth in combination with an equally rapid increase in urbanization is making urban areas a focal point of urgent ecological and social questions. In many places, climate change has long since ceased to be a future nightmare, but has become a reality that can be experienced every day in overheated streets.With their large, cooling and shade-providing canopies, trees can make a valuable contribution to address this issue and to increase well-being and human health. However, as already shown, it takes decades for them to develop their full size and thus also their full climatic effect and health benefits. If Baubotanik seeks to make a relevant contribution to answering these questions and to enhance cities with living structures in the scale of multistorey buildings, the solutions must be found right here and now – and not at some undetermined point in the future. Initial findings from tests and experimental buildings of Baubotanik research group, such as the Baubotanik Tower (Fig. 3)and the Plane Tree Cube (Fig. 4), demonstrate that living buildings can be constructed directly in the dimension of fully grown trees through techniques such as the newly developed plant addition. This technique is based on the fact that trees have the ability to compensate for the loss of organs by generating new ones, either in the same locations or elsewhere. If several plants are inosculated and thereby merge into one organism,the former individual ones no longer require all of their biological parts. This means that the roots or the leaves, or even both, can be removed,provided that the inosculated structure as a whole can compensate for the loss. The plant-addition technique uses young plants that are arranged in space above and adjacent to each other and connected in such a way that they merge into one network-like plant structure. Only the lowest plants are planted in the ground, all others are planted in special containers with an automated system that continuously supplies them with water and nutrients to allow them to grow. As the network develops, the roots embedded in the ground that have more space to exploit additional resources grow more vigorously than those placed in the containers. Once the inosculation have developed,water and nutrients can be transported via the artificially created plant structure from the roots in the ground to the uppermost leaves, and the roots of the container plants become obsolete.Step by step, the high-level roots can be cut off,the automated watering system can be removed,and ultimately, the living structure becomes selfsufficient. Simultaneously, the plant structure becomes stronger and eventually self-supporting due to secondary growth in circumference so that the scaffolding, which was initially required to support the containers and the young plants, can be removed[3,20,24].

3 Outlook

In this way, Baubotanik allows to create green structures as integral elements of the built environment, which are usable within a very short time and offer many ecological qualities of decadesold trees. These include, in particular, microclimatic effects such as cooling through evaporation and purifying the air by binding fine dust. The design for the “House of the Future” in Berlin by OLA(Office for Living Architecture) uses these effects to develop a building that is – at least partially –cooled and conditioned by trees and at the same time has a positive influence on the microclimate of its surroundings (Fig. 5).

A large number of studies prove that this effect has a decisive impact on people’s health and well-being. For example, Kardan et al[25]found that people living in neighborhoods with many street trees suffer significantly less from cardiovascular and metabolic diseases than residents of the same age and income in neighborhoods with fewer trees.If the subjective evaluation of one’s own quality of life is compared, evaluated and correlated with the age and income structure of the population,it is found that people in tree-rich streets evaluate their quality of life just as high as people in a treepoor street who are 7 years younger or earn at least $10,000 more per year. This not only proves the added value for the individual resident, but also documents an overall economic benefit of urban trees. If Baubotanik succeeds in creating structures that unfold these health, psychological and socio-economic effects, the efforts involved in construction and maintenance will be more than justified. Then, entire cities – and not just the sparsely populated suburbs – can be understood as health-promoting tree gardens that develop in coevolution with the human inhabitants and represent a fundamental part of the larger “planetary garden”imagined by Gilles Clement.

Sources of Figures:

Fig.1?Cira Moro. Design: F. Ludwig, O. Storz, C.Hackenbracht; Fig. 2, 4-5?OLA – Office for Living Architecture; Fig. 3?F. Ludwig. Design: F. Ludwig, C.Hackenbracht.

(Editor / LIU Yufei)