A Retrospective Comparison on Europe and China Ecological Wisdom of Pre-Industrial Urban Communities of under the Lens of Sustainability Pillars

Marco Casazza,Gengyuan Liu,Francesco Maglioccola,Massimiliano Lega

1 University of Naples‘Parthenope’,Department of Engineering,Centro Direzionale,Isola C4,80143,Naples,Italy

2 State Key Joint Laboratory of Environment Simulation and Pollution Control,School of Environment,Beijing Normal University,Beijing 100875,China

3 Beijing Engineering Research Center for Watershed Environmental Restoration&Integrated Ecological Regulation,Beijing 100875,China

Keywords Sustainable urban environment Pre-industrial cities Sustainability pillars Ecological wisdom Eco-coupling

Abstract The design of a sustainable future for cities is of paramount importance,considering both the need of a societal transition and the fact that nearly half of the world’s population is living within growing urban areas. While this process is generally driven the development of technological and socioeconomic solutions,this work opted for a different approach.In particular,the existence of a prior urban sustainability wisdom was searched and assessed under the lens of the three known three pillars of sustainability(i.e.:environmental, economic, social). Wisdom is here considered as the application of a tacit knowledge oriented toward the stability of the urban environment and a city social and economic system. Focusing on the preindustrial urban context in Europe and China, a review was conducted to collect and put together the evidence of such a wisdom. Results evidenced that the urban structure,the urban-rural gradient,food production and the management of water resources were carefully planned to guarantee the survival of the cities inhabitants. The problem of poverty alleviation,still remarked by the sustainable development goals,was already considered as a relevant factor for economy.Trade was anotther relevant element of urban development. Inclusion,belonging to the social dimension of sustainability,was also supported the mainainance of public spaces. Furthermore,the less-considered cultural factors,that are now regaining attention under the light of United Nations Framework Paris Agreement,played an important role, considering, for example, the birth and growth of universities. The present study, which would require further investigations about the socioeconomic dimensions of sustainability, summarized the existence of the hypotesized sustainability wisdom,evidencing the importance of integrating the historical environmental and socio-economic dynamics to improve a sustainable urban planning. This research will need to be deepened trough archaeological, documental/historical and post-processual approaches, to address the need of transition toward a more equitable and sustainable postfossil fuel societies within their urban context.

1 Introduction

Urban population is increasing worldwide. United Nation analysis showed that 54% of world population lives in cities, while a further increase, up to 66%, is foreseen by year 2050 (United Nations, 2014). By 2030,the urbanization phenomenon will also fully involve the developing world, for which more than a half of its population will live in cities in a few decades(Montgomery, 2008). The number and size of the world’s largest cities are also unprecedented. In fact, almost 400 cities, which are prevalenty located in the developing world,contain a million people or more(Cohen,2006).

The increased pressure of growing population within cities, the present environmental degradation, as well as the risk of social unrest, are increasing, as well documented in the literature. These facts are confirmed by the literature on environmental degradation and resources depletion (e.g.: Gleich, 2014; Hougue and Pincetl,2015;Kelley et al.,2015),on economical impoverishment(e.g.: Levine et al.,2008;Donald et al.,2014;Obeg-Odoom,2015;Robinson,2016)and on potential social unstaibilities(e.g.: Buhaug and Urdal,2013;Marinkovi,2013). Consequently,the future of cities is under risk(Moriarty and Honnery,2015). This is why the challenge of making the urban lifestyle sustainable is still open.

Cities can be fundamental drivers of transformation(World Bank,2010;UN-HABITAT,2011;UNEP,2012),that should be driven by an adequate and informed planning, keeping in mind the multi-dimensional nature of sustainability, that is well-synthesized by its three pillars. There are clear examples that integration of adequate sustainability models into planning practices can improve the quality of life in previously degraded urban environments (Basiago, 1998). With this respect, the concepts of urban sustainability and ‘smartness’ would require a further clarification (e.g.: Berger, 2014; McHale et al.,2015). Moreover, assessment methods should be re-discussed under the light of the most recent literature (Liu et al., 2014; Beloin-Saint-Pierre et al.,2016).Finally, urban governance systems, as drivers of adaptive strategies, need to be informed by urban metabolism and socio-ecological modelling,which include also human perceptions and activities(Li et al.,2016).

The process of urban re-design,starting from these challenges,should be supported by evidence-based practice, which needs to be implemented (Krizek et al., 2009). The introduction of new technologies and big data analysis will allow the collection, integration and analysis of a huge body of information, supporting such a process in the context of a“real-time city”(Kitchin,2014;Al Nuaimi et al.,2015;Malik et al.,2018). However,the real possibility of a future development under the condition of resources scarcity or contrains is underinvestigated. This is why we could learn much from the study of pre-industrial cities, whose survival was constraned by the availability of natural resources and adequate economic and social behaviours. In fact,community based adaptation,A cimmunity-based process to empower people in coping with different impacts,like climate change,was at the base of the survival of cities(Reid,2016).

This work aims to investigate, reviewing the available peer-reviewed literature, the existence of planning patterns or practices, that, today, could be broadly referred to the different domains of sustainability. Being these patterns or practices often uncodified, we refer to them as forms of urban ecological wisdom (Young,2016). In particular, we reviewed the characteristics of pre-industrial cities in Europe and China under the lenses of environmental, economic and social sustainability.

This work introduces the readers to the context of urbanization,with a focus on the medieval period,prior to the diffusion of coal in the XVI century. Then,the research approach is further defined. Following,the ecological wisdom referred to environmental, economic and social sustainability are discussed, considering historical and archaeological findings, as well as social and cultural practices, documented by the available peer-reviewed literature and original sources.

It is important to remark that sustainability was not a conscious choice in that age. It was,instead,a implicit necessity of survival. In fact,in case either of resource depletion or of socio-economical injustices and inequity or other instability factors, the stability of urban settlements would have been threated. In other words, cities struggled both for their structural survival as communities, and, somehow, for the inclusiveness of their social structures,depending on the social values of that time.

The novelty of the review consists in its multi-disciplinary approach, merging the literature evidences from different disciplines, while contributing to the present demand of studies in the field, evidenced by important existing research hubs,such as the Integrated History and Future of People on Earth(IHOPE)in the framework of Future Earth network. The second novelty is about the comparison between the Western-Europe centered view of history and the long civilization history of China. Third,the comparative approach evidences the implicit traditional ecological knowledge already existing in the pre-industrial age,which is now crucial for developing a sustainable lifestyle for the urban environment.

2 Object of investigation and review method

2.1 Object of investigation

This review is focused on the search for evidence of an existing wisdom about the sustainability of urban areas,with a specific interest for medieval Europe and pre-industrial China. According to Merriam-Webster dictionary,wisdom is a wise attitude,belief,or course of action. We use this term to distinguish it from any knowledge in a fixed or codified form,since no specific codification of habits with respect to sustainability existed at that time.Following the line of Stenberg (1998), as well as of other authors (e.g.: Baltes and Staudinger, 2000; Turner et al., 2000; Kunzmann and Baltes, 2003), wisdom is considered as “the application of tacit knowledge as mediated by values toward the goal of achieving a common good”. In the case of this work,wisdom is referred to an uncodified set of patterns or practices, reflected in different urban structures and areas. This approach emerges from from previous study about ecological design (Van der Ryn and Cowan, 1996), giving directions to design ecologically-wise solutions.

Several researches proposed a connection between ecological wisdom and traditional ecological knowledge(Liao and Chan, 2016). Here, a distinction between the two terms is applied. The definition of traditional ecological knowledge would perfectly fit to the topic of this work,referring to ecological knowledge held either by pre-industrial or less-developed communities (Berkes, 2012). However, a second option allows a better distinction between the two concepts. In particular,Such a wisdom,derived from the knowledge,understanding and application of sustainable principles can inform urban planners and designers, supporting their action for a urban sustainable transformation(Wang et al.,2016).

The wide historical time-frame considered in the present study needs to be understood, considering the different historical evolutions in Europe and China. Medieval cities in Europe evolved from the late antiquity(in the IV century AD),defining a separate identity around the VIII-IX centuries AD(Le Goff,2011). On the other side,the nature of urbanism in China is more difficult to describe. Urbanization in China is a very recent phenomenon.However, the North China Plain was one of the oldest world regions to witness the urbanization phenomenon(Wheatley,1971). Nonetheless,at the beginning of the twentieth century,China was still prevalently dominated by rural areas(Friedmann,2006).

The comparison of urban realities in China and in Europe is made more complicate by the current uderstanding of the world“city”in the Chinese context,being referred to three different levels: municipalities;prefecturelevel; country-level. Beijing and Shanghai belong to the first level. Shenzhen in Guangdong Province is an example of prefecture-level city. Finally, Yiwu(administered by Jinhua, a prefecture-level city) belongs to the third type. This classification also influences the urban statistical classification in the official Chinese databases.The union of central sub-districts of a country-level city represent the reality closest to what is defined as city in western countries. Despite these differences in the urban evolution of Europe and China,parallel elements of convergence with respect to sustainability pillars were considered in this work.

2.2 Review method

Urban sustainability is often used as alternative to sustainable urban development. According to Maclaren(1996), who introduced the former term, sustainability generally refers to a set of stationary conditions, determining the sustainability of a city. Conversely,sustainable urban development refers to the dynamics determining the sustainability of an urban evnironment (Yigitcanlar and Teriman, 2015). This paper specifically refers to urban sustainability. For example,Wu(2014)found some key elements of urban sustainability: environment(ecosystem processes, ecosystem services and biodiversity, which are associated to the natural biota); the social dimension (health, security, freedom, culture, availability of resources). However, economic factors were excluded from the list.

Indicators of urban sustainability are difficult to define because o fthe diversity of the city (Tanguay et al., 2010; Liu et al., 2017a). Moreover, indicators should be defined considering a city as a complex system(Maranghi et al., 2020). The three pillars of sustainability, also known as Triple Bottom Line (TBL), can be used as a framework to define such indicators(Tatham et al.,2014).

Considering the integration of bio-physical and socio-economic dimensions (Pirenne, 2007), Newmann(1999) listed a set of basic areas for urban sustainability indicators: energy; air quality; water, raw and waste materials; landscape; biodiversity; human health; transportation infrastructure; urban livability. More recently,Verma and Raghubanshi (2018)listed a set of goals, referred to the TBL,that,after being implemented constituted the basis for our bibliographical reswarch. Table 1 reports the goals,according to the authors,as well as the search keywords, that we applied, as referred to the TBL.With respect to the work of Verma and Raghubanshi(2018),some modifications were applied. With respect to environmental sustainability, the topic of urban form was missing,as well as the relation between urban and rural areas. This topic pertains the domain of landscape management, a key factor in urban planning, that is connected to land use. Food and water, as key resources,are referred to the environment domain, instead than the social one. An investigation of environmental foundations of social and economic development, tipping points and tresholds, and the ecological basis of economy are excluded from this review. The reason for exclusion of such points depends on the full dependence, in the pre-industrial age, of economy on natural resources, as discussed by Sertorio and Renda (2018). The analysis of economic sustainability would require a quantitative approach, that would be impossible in our case, since economic records of that time are scarcely analyzed at the moment. Trade, implying the transfer of environmental resources and money,is a relevant factor in economy. Considering the dependence of cities on external resources, this factor was included in the search. The concept of poverty is also included in this work, being referred as distributional equity in the previously identified goals. Social sustainability aspects were included in our search. Social cohesion was searched in the existence of public spaces and infrastructures, that allowed to support a greater social inclusion and to develop specific practices.

More in detail, in this work the environmental side of sustainability was assessed against: spatial planning,urban structure, urban-rural connection; food production; water management; biodiversity; energy-related resources (primarily wood). Air quality and waste management, which are considered within the multiple set of measurable indicators in the extended metabolism model,are not included here,due to the lack of available data.Economy and its dinamics was also considered,basically in relation to handcraft,service and trade sectors activities. On the other side,transport was excluded,due to its limited environmental impact during the pre-industrial era, particularly before the age of long-range geographic explorations. Public health, social cohesion, the development of associated public spaces and the cultural dimensions, which were almost excluded by Newmann(1999),are discussed here as parts of the social-side of sustainability.

The bibliographical research was performed through“Web of Science”and“Scopus”search database. Both original and review articles were included as sources. Results were, first, limited, including only the last five years of published works. The search output time limitation was, then, removed, in order to look for potential important investigations of the previous years. Finally, the results were further selected on the basis of abstract content and relevance of the subject.

The first part of the review, focused on the environment, was based on the search of the following words:“urban shape”, “urban-rural”, “water use”, “land use”and“urban agriculture”, together with“urban” or“city”and “medieval”. For the economic sustainability, where the keywords were “economy” and “production”, together with“urban”or“city”and“medieval”. The same approach was used for the social sustainability, where“public space” and “public health” were used. The study of some reference works for European and Chinese urbanization,to which we referred previously,were also considered. Finally,an attempt to discuss about culture and sustainability was also developed,based on the keywords“culture”and“instruction”.

Table 1 Goals referred to different sustainability pillars (source: Verma and Raghubanshi, 2018), and derived search keywords.

The review section, which includes three sub-sections, is based on a comparison, for each given indicator,between the present knowledge and the historical evidence on each different issue. The literature references,thus,will refer to both.

3 Review and discussion

3.1 The environment

The urban environment consitutes the substrate for any socio-ecological development and growth. The first environmental dimension of any settlement is space and its structure. Initially, existing settlements were small and surrounded by vast rural areas(Antrop,2004). Cities were an exception to this rule. Suburban and peri-urban areas, together with cultivated urban areas, were the basis of urban life. There, citizens developed agriculture and farming for their subsistence (Ronchi et al.,2014). For example,in central Italy,in the Renaissance period(XVI century), gardens, made by a combination of fruit trees, flowers and forest products, were associated to the nobiliary residences (Botti and Biasi,2009). This urban form is still preserved in many cities in central and northern Italy preserve signs of pre-industrial gardens in their form,even if adapted over the centuries. The same was true for China.

There can be little doubt that sprawl,following Bruegmann’s definition(Bruegmann,1977),existed around many ancient cities. In fact, walled cities usually developed beyond their borders (Smith, 2010). Urbanisation transformed the landscape,impacting on its patterns,functionality and dynamics(Haase and Nuissl,2010). The transition from urban to rural areas gradually became more defined, later becoming a conceptual dichotomy in the nineteenth century (Davoudi and Stead, 2002). The “urban fringe”, being the built area just outside the administrative limits of a city, is another recently-defined element of transition between urban and rural areas(Pryor, 1968). This distinction, observable in the urban evolution in Europe, was also present in China. Farreaching transformation of the conception of the city in relation to the countryside took place during the period of the Qin unification (ca. 300 BC)(Xu,2000). In early Zhou dinasty (1056 BC-256 BC),the“country”, not only denoted an enfeoffed territory but also meant the walled city,where the seat of the head of the fief resided.In political terms,a city of this kind was constructed to defend the authority of a prince or duke over his fiefdom,while the prasantry is living outside of the wall. The walled city was conceived as a sort of civilized island,surrounded or threatened by hostile peasant communities(Xu,2000).

Two main extended urban spatial patterns existed in medieval Europe. The term ‘extended’ is referred to their extension beyond the urban boundaries. From one side, the city, surrounded by vast rural areas. On the other side, urban clusters at relatively close distance. In the XVI century, Paris, London, Lisbon, Naples,Constantinople and the Hanseatic towns, such as Danzig and Novgorod, were good examples of the first case.Urban clusters,instead,were found in Flanders and Northern Italy between the XI and the XV centuries.

Internal patterns also existed, related to the urban structure and shape. The existence of structured complex patterns is currently recognized as a relevant feature of resilient cities (Salat, 2012). In fact, a coherent urban morphology can be defined considering the fractal assemblage of patterns across different scales (Salingaros,1998). The fractal approach, while showing a high plasticity, enables a higher connection among scales –particularly the smaller ones – and a larger degree of redundancy within the road network. Salat and Bourdic(2011) suggested the comparison between a urban structure and an arborescence, where a highly hierarchic structure exists, which enables an increased efficiency of the system. This confirms the previous findings by Alexander (1965), who compared the structure of street networks to trees and leaves. In fact, small streets show a higher number of interconnections and connections to higher-level ones in what is known as semilattice structure. The same is found in the veins system of most deciduous trees, which not only have a clear scale hierarchy,but also display a higher connectivity among the midsize veins and the venules.

Fractal structures already existed in late-antique and medieval European cities (Salat, 2011). These urban features,as part of cities’identity,was preserved along time,becoming a clear sign of resilience. Skinner(1976,1977) observed the same facts for China, where urban structure and hierarchy were generated on the basis of distinct economic systems and trade linkages among the hierarchy of central and local metropolises,on one side,and regional,greater,local cities and market towns,on the other side.

Cities require food for the survival of their inhabitants. It is evident that urban and peri-urban food production partially contributes to address food security in urban centres both in developed and developing countries(Ghisellini and Casazza, 2016). Presenty, 15% to 20% of the global food demand is addressed by food production in cities(Armar-Klemesu 2000). During the Middle Ages,European urban gardens provided food and curative herbs, as well as flowers (O’brien and De La Escosura, 1992). The importance of food production was already remarked in a medieval text by Thomas Aquinas (1225-1274). The author reported the relevance of internal cultivation and food supply by trade, writing that the first option is preferrable with respect to the second (Aquinas, 1949). Some historical case studies were reported by Elmqvist et al. (2013). The first one is about cities in Meso-America. Due to the variability of seasonal conditions and the energy cost of inland transport, urban Maya Indians used to produce food in areas close to their cities,even if they also traded goods from long distances. In particular,urban fertile soils,fertilized using the organic waste produced within the city,were partly used as urban infields. This care for gardens guaranted the food security for the population, as well as other stable ecosystem services. The rich level of biodiversity still found in some cities is witness of such a co-evolution. The second case is about Constantinople. In this case, periodic sieges posed a threat to food security. This forced its inhabitants to erect the Theodosian Wall, located 1.5 km westwards the Constantine Wall. Major water cisterns, as well as a 3 km2green common space, were included between the two walls and used for cultivation and pasture. The whole agricultural area, including a 2 km2space just outside the walls,measured about 15 km2. A third case was discussed by Billen et al. (2012). They showed that the evolution of Brussels(Belgium)was strictly related to the evolution of agriculture in the close rural territory. The definition of a spatial structure came later,only when Brussels became a market centre. The evolution of spatial planning in proximity of London was triggered by the demand of fuel, drink and food, as well as by the presewnce of several waterways,which were used instead of land transport(Keene,2012).

The preservation of biodiversity is important to guarantee the communities survival. A couple of examples in the past were reported again by Elmqvist et al. (2013). The contemporary Istanbul region still has remnant seminatural patches, deriving from the integrated evolution of the environment with cultural practices. The Stockholm National Urban Park, in Sweden, represents another example of biodiversity-rich land, previously used for producing food,fuel,fiber and other useful materials.

Water is a vital driver of urban evolution (Kaushal et al., 2015). Often, urban structure, functions, and services were either strongly shaped or influenced by water bodies. Cities located on a river developed a relation among ecosystem services, man and technologies which mainly evolved in two steps(G´omez-Sal et al.,2003).In the first one, local communities used renewable products, which could be replaced by a new supply. Later,production systems evolved, implementing the extraction and transformation of valuable good . This is why a low-volume trade of expensive goods gradually grew. During this stage,ports were also developed. Within this context, rivers played a crucial role. In fact, rivers were used as effective ways for tranding goods. Moreover,water was used to supply water for different handicraft working processes, whilw serving also for wastwater discharge (Levin-Keitel, 2014). Case studies reported the case of the city of Tor`un (Poland), near the Vistula River, and Dublin (Ireland), where rivers supplied water through secongary water courses (Rivers Poddle and Dodder and the Grand Canal)until the mid-19th century(Czarnecki et al.,2014;Kelly-Quinn et al.,2014).

Waters were already used in the past to improve the urban sanitation. Leonardo da Vinci designed a water system to remove urban waste from the streets(Meehan et al.,2013). Later,the idea of an‘odourless city’was implemented, in relation to the cleaning of public spaces using water. The same practice was exported by the Spanish colonial government in Mexico City. Moreover,patterned after ancient Aztec infrastructure,a sewerage system was built. All the basic water-related technologies were developed from ancient times: cisterns(Mays et al.,2013),water pumps(Yannopoulos et al.,2014),and aqueducts(De Feo et al.,2013).

Some details about water resoruces management in historical China are available. Water was relatively abundand, even if very unevenly distributed along China’s long agricultural society. In specific seasons or regions, both droughts and hydro-geological hazards could be observed. These conditions, together with the gradually increasing need of lands for agriculture and urban development, led to a qualitative change on the relationship among human communities, landscape and waters. For example, in the Tang dynasty, Guanzhong and the surrounding Loess Plateau region not only were theatres of frequent political conflicts due to the excess of land reclamation, but also of frequent “mud rain” episodes, associated to soil erosion and fragmentation.Another example. After the collapse of Han Dynasty (II century AD), during the Late Antique Little Ice Age(LALIA), in the Chaohu Lake Basin, a combination of natural hazards, as well as the North-South political and geographic division led to a war. This, in turn, caused the gradual abandonment of the ancient “Chao-Fei Channel”, while it destroyed its agricultural and economic background (Wu et al., 2012). Consequently,settlements also started to decline, as witnessed by the reduced number of archaeological and burial sites. It was,then,understood that a comprehensive utilization and management of water resources had to rely on better and stronger management,where both the government and non-governmental parties played a crucial role. The society responded developing and a legal framework to implement the conservancy and management of water resources. In parallel, the use of water resources was prohibited, in order to avoid water-related conflicts. As a result, the integrated management of water resources ensured the basic water security and the rights to water access for the people in the agricultural era. Three major goals were reached: flood control, irrigation and water transport. An improved interaction between communities and water resources allowed to promote a water conservancy civilization. In fact, the ancient Chinese water conservancy projects were far more than the ones in Western countries. For example, during the Tang dynasty, 16 different irrigation projects were developed.After that, the number continued to rise sharply. Around year 1400, about 30%of the cultivated land area was irrigated (Wang, 2005). It can be said that no country like China mobilizezed a lot of resources and labor to carry out large-scale water conservancy facilities.

3.2 The economy

Current public economic debate is crossed by some ‘hot themes’. Among the others: the value of money; the change of economic model(i.e.: circular economy,stationary economy,etc.);economic inequities related to the increasing porverty; the relation between economy and environment. It can be said that the present economic state in the western world evolved and complexified from the medieval one, since the even the premise of industrialization and economic thought are rooted in that time, after the collapse of the Roman Empire. It is not possible,for sure,to take direct inspiration from the medieval cities for thinking about the future economic sustainability. Later, policy debates often focus on cities and the sharing economy (Rinne, 2014). Meanwhile,circular economy,based on products recycle and reuse,is gaining public interest and might shape also the future of cities(Gunter,2013;Maranghi et al.,2020).

New visions are needed to promote informed policies and develop adequate incentives to promote innovative and sustainable business strategies. Consequently, a summary of existing evidences from the pre-industrial past is reported, to give the opportunity of future reflections with respect to this issue. During the collapse of the Roman empire,cities were gradually abandoned. In a letter,Ambrosius of Milan(340 AD–397 AD)described the status of a large number of semi-distroyed cities(Cipolla, 1974). At the end of X century this phenomenon came to an end. The existing fortified villages, called curtes, gradually grew up, becoming also market places.Thus,after a few centuries,the troubadour Chr´etien de Troyes(end of XII century)witnessed: “And one can say and believe,that there is a fair every day in the city”.

Urban migrations, depending on a “push and pull” process, were drivers of urban economic development(Cipolla, 2007). While also the rural economy, strongly supported by monasteries, was improving between the X and XIII centuries, local feudal powers represented a factor of social inequity in these areas, forcing people to move toward cities. Growing up,the urban environment became the place of co-existence of both low nobles, merchants and craftsmen. A new middle-class gave impulse to the cities economic development, while commerce supported the growth of urban-based trade(Le Goff,2011). Corporations and guilds appeared from the XI century, as well as markets (later, from the XII century) and the precursors of the tertiary sector(Clark,2009). The development of trade created a conflictual view,as reported by Thomas Aquinas, who was witness of such a change. In particular,the presence of foreigners was looked with suspect for the risk of change of civic morality,wich was argumented considering their different moral approach to money as wrong(Aquinas,1949).The same author considered the increase of urban population as a risk for urban stability due to the problem of dependency on external supply of goods.

The theme of poverty,which was particularly related to the rural world,is still a present threat to economic sustainability. The importance of poor in the public discourse is not recent. A new vision on poverty emerged,maybe for the first time,in the transition between the Roman empire and the Middle Ages. In the Roman world,charity was already an existing practice, but mainly focused on private investments for public works or public games with the purpose of supporting private political carreers(Brown,2012). Moreover,local administrations used to provide economic support to the poor citizens for their basic needs(i.e.: food). Nonetheless, there was no socio-economic support for non-citizens. As described by Peter Brown,the advent and spread of christianity evidenced, for the first time, the global dimension of poverty, and, along with the creation of local bishoprics,it stimulated a diversion of private investments toward the local Christian communities,which increased investment to support the destitutes. This didn’t solve the problem,but gradually introduced a new socio-economical vision,based on inclusiveness, starting from the villages where the bishops resided.

Looking to the economic situation in China, cities were shaped by the specifical presence of a urban class,that could be cautiously identified as bourgeoisie (Xu,2000). Yet,this fundamental social and political distinction between cities in imperial China and their Western counterparts did not conspicuously arise in the pre-Qin dynasty (before 221 BC), when the cities in China contained “the same basic ideas” and developed in a way similar to the feudal West. Considering a larger pre-industrial period, China performed much better than the Europe,enjoying a superiority in agriculture, military power,commerce,science and technology(Deng,2000).Urban citizens had an incentive to study and accumulate wealth, due to the exisisting social mobility as well as to the opportunity of internal migrations. On the other side,producers were incentived through well-defined property rights, which were relevant, considering the high number of small-scale farmers, whose survival was based on private ownership of lands.

3.3 The social dimension

The social dimension within the urban environment can be referred to various subjects, starting from the social inclusiveness and justice. Social inclusion and social cohesion are basic terms in the context of social sustainability. The former relates to the access of individuals to social relations and to institutions (Beck et al.,2001).The latter identifies the quality of social relations,based on a common ground,defined by identities,values and norms (Beck et al.,1997). The Wirthian theory, developed in Chicago (USA),approached to urban sociology,defining urbanism as a way of life. This theory fixed a set of principles, relevant both at individual and community levels (Wirth, 1969). In particular, population growth and its increasing heterogeneity were identified as the main social and psychological drivers of urbanism. Specific indicators of life quality, together with metrics of social justice, were implemented as relevant (Knox and Pinch, 2010). This interest in measuring social well-being derived from the evidence of a growing social inequality in Western societies, influenced by European continental philosophy, which draw a special attention upon ideas of social exclusion. Poverty evolved,as a concept,becoming more than a mere lack of access to material resources. Instead, it embraced the dimensions of social inclusion, influencing a new understanding of citizenship. Lately, the quality of life has been reconceptualized, integrating the environmental dimension and considering a wider perspective than a purely economic one. Finally, public spaces were also included as relevant to trigger a sense of citizenship, based on their aesthetic and social dimension(material form vs. use and meaning)(Garc`ıa-Dom´enech,2015).

The social dimension is generally supported by interconnection infrastructures. Today, along with transportation system,we should also include the digital dimension(e.g.: social networks). During the middle ages,interconnections were guaranted by the existence of major roads,which facilitated the development of an urban society, of communication with their hinterlands, as well as trade with other cities(Madanipour, 2013). Crossroads were the main nodes of urban development inside cities, since they implicitely determined the potential meeting spaces for people. The first public space in the urban environment was constituted by roads. Obviously,the development of new transport and communication technologies altered this framwork in the following centuries. Consequently, present time analyisis is more complex. This is a reason of the past reduced average length of main street segments with respect to the present ones. This was evidenced in a study, showing that much smaller roads existed in the past with respect to contemporary cities (i.e. Garden City, Radiant City and New Urbanism)(Porta et al.,2014). A specific pattern, the‘400-metre rule’,was identified. Residential areas,also known as sanctuary areas(Appleyard,1981),were bounded by main streets,intersecting at intervals seldom exceeding 400 metres. These intersections were not based on rectilinear grids by principle. According to the same study, this rule followes the mean extension of pedestrian movements, respecting a self-organising logic of urban social life typical of pre-industrial times. Later,with the advent of automobile and highways systems,professional urban design paradigms became necessary in the early 20thcentury. The growing urban context,supported by the growth of physical networks, gradually transformed the existing socio-ecological systems,which gradually modified their structure.

Public spaces characteristics depend also on the communities that created them (Sokolowski, 2014). Their feature in Flanders during the medieval period represent a clear example of this. In fact,a distinct urban identity appeared there during the conflict among cities and the nobility of Flanders, France and Burgundy. Consequently, public spaces were used to protect peoples’ political rights and liberties. From the Chinese side,cities did not totally lack public squares and public gardens. However,citizens probably preferred small,private,but open and sunny courtyards(Xu,2000). Nonetheless,the very few cases of open areas do not necessarily indicate that Chinese cities had to a lesser degree a similar need of public squares than their European counterparts. It should also be noted that public gardens, accessible to both urban and rural residents, especially on festivals and holidays, were located in the rural areas around the city as much as within the city walls, where natural landscapes were transformed.

Urban practices should be considered along with public spaces and infrastructures. As a way to shape a common identity. In fact,practices,as routinized behaviours(Reckwitz 2002),can be also associated to a spatial dimension. Archeological remains support the identification of these practices on the basis of some premises(Christophersen, 2015). In particular, given their characteristics, physical resources are required to identify the purpose and intent of practices. Specific patterns of routinization can be identified through the traces of rearrangement in relation to specific spaces and areas. These spaces or areas, in turn, are built and adapted according to an intentional meaning. Three patterns of practice can be identified accordingly. Proto-practices were non-stabilized and routinized. ‘Meaning’ emerged, as a second phase, together with specific physical objects and structures. Stabilized practices exist, as a third phase, when a link appears between routinized actions,objects and structures.. In our case,town houses represented the main space of practice and experience.Coherently, residential areas and land ownership arrangements were studied in detail. In the typical smallscale and fragmented medieval townscape,activities were concentrated in small spaces. There,widely different practical tasks were performed in close physical proximity,which required a detailed spatial division,that caused the formation of bundles. Gradually, areas evolved into specific quarters, where craftsmakers shared the same spaces with a simbiontic logic, that resembles the current paradigm of industrial symbiosis. The space for activities gradually moved, becoming integrated market areas to meet the demand and increase the transit of potential buyers. This evolution occurred in“sequence, synchronization, proximity or necessary co-existence”(Shove et al.,2012). This is why advanced communities of workers grew up together with production processes,that shared production sites and needed further synchronization and shared expertise. The evidence of the relation of public performance and spaces is further confirmed from the study of medieval literary documents and is worth of future investigation(Clarke,2015).

This proliferation of urban centres and activities simultaneously exacerbated the existing social pressures.In particular,it became necessity to implement a safe and healthy environment. With this respect,the challenges of pre-modern cities communities were great. However,this challenge became explicit in some case,becoming also an explicit commitment to people’s greater health (lat: pro maiori sanitate hominum)(Geltner, 2013). For example, in the early fourteenth-century, the government of Lucca (Tuscany, Italy) promoted public hygiene measures, showing an early concern for preventative public healthcare. Several documents of the same epoch,in Italy and elsewhere,report the efforts of urban administrations toward this goal. In the case of China,before the twentieth century, local autonomies were the substitute of structured urban administrations. In this context,communities allowed an equal access to public spaces to the members of all social classes. Streets and shared spaces were the place for recreational and commercial activities. Neighborhood-organized systems, known as “Baojia”, leaded by local residents, controlled the streets, with a little direct involvement by the central government. Consequently,local activities largely reflected a degree of community cohesion and control(Wang,2003).

3.4 Discussion

Biophysical and socio-economic forces in their mutial interactions shaped the evolution of cities (Kaniewski et al., 2013). This is why an urban ecosystem is a socio-ecological system, where the environmental and the social dimenstions both coexist and interact (Su et al., 2010). The urban ecosystem is dependent and fragile.In particular, the huge demand of resources as well the impacts of waste and pollutant emission constitute a weakness for cities. Consequently, human activities can challenge the ecosystem’s regenerative capacity,impairing ecological functions and societal services. Thus, management actions directed toward urban health are needed. These actions need to be based on reliable scenarios, which are generally derived by present-day data, which should be based on the availability (and nature) of various indicators, which make the process of scenarios drawing easier. The integration of different monitoring options together with use and management of big data can support the development of adequate remediation and mitigation actions.

On the other side, it is possible to look back to urban history and to ecological wisdom. Merging together the evidence from past studies in different fields,a first comprehensive view can be summarized(Table 2).

From Table 2, a summary of evidences of an existing ecological indicators emerges with respect to urban sustainability both for Europe and China. This doesn’t mean that pre-industrial cities were sustainable by definition. Nonetheless, they needed to struggle to survive, basing their survival on ecosystem services and socio-economical dynamical equilibrium. This‘dialogue’between the human communities and nature,was not supported by fossil fuels(carbon combustion was introduced mainly from the 16thcentury AD).This makes this analysis interesting,since there are clear plans to create future low-carbon societies.

A still debated subject, which is generally missing, is the importance of culture, as a further pillar of sustainability. In fact, culture (as education and skill development) was previously included as a part of social sustainability (Verma and Raghubanshi, 2018). This fact is particularly important in the context of landscape and urban planning. In fact, as written by Antrop (2005), “landscapes change because they are the expression of the dynamic interaction between natural and cultural forces in the environment”. First, it is important to consider the relation between the ecosystem and the culture,through Cultural Ecosystem Services(CES).They are defined as“non-material benefits people obtain from ecosystems through spiritual enrichment,cognitive development,reflection,recreation,and aesthetic experiences”. According to the categorization system of CICES(Common International Classification of ES),CES are also identified either as physical-intellectual interactions or symbolic and spiritual interactions with biota, ecosystems and land/seascapes (Maes et al., 2013). CES are also defined as the contribution of ecosystems to non-material benefits, emerging from the relation between humans and ecosystems (Chan et al., 2012). Accordingly, ten different services categories are identified. In particular, cultural diversity, spiritual and religious values, knowledge systems, educational values, inspiration,aesthetic values, social relations, sense of place, cultural heritage as well as recreation, and ecotourism (MA,2005).

In the Middle Ages, these processes were evident trough the literary production. We could, for instance,consider the case of Boccaccio Decameron,which is set in a garden,or the case of the edenic view in the letters of the hermit Pier Damiani(2000). The role of creativity and arts was also important in the urban context. In fact,creativity and arts are triggers of aesthetic reflective actions, which are important for sustainability (Casazza et al.,2017). Today,creativity is a relevant ingredient to cope with the current individualistic/atomistic perspective towards a more contextual and collaborative approach to community life (Montuori, 2013). There is no need to stress the beauty of Medieval artistic production, which is still available trough buildings or work of arts,such as frescoes,or literary production, such as the poetry of 13th–14th century(for example,in China and in Italy),which were mainly developed within a city context. Finally,considering that a global trend exits,where universities are collaborating with local government,industry and civic organisations to advance the sustainable transformation of a specific town,city or region(Trencher et al.,2014),we have to take into account the creation of university. In fact,the first real known university was created in Bologna in 1088. It is important to stress the fact that this subject is regaining attention under the light of Paris Agreement on international climate policies(UNFCCC,2015),which underlined the importance of traditional knowledge as an important part of culture for sustainability.

China,whose civilization history spans several thousand years, is basically an inland country, mainly characterized by mountain or hilly areas (Wang et al., 2011). Based on a huge presence of marginal environments,people had to understand and efficiently use the eco-complex and to take the strategy of accordance with,rather than against, nature. The most fruitful period of the Chinese human ecological thoughts was Chun-Qiu (from Spring and Autumn to Warring States: 720-221 BC).At that time,various thoughts were developed, including Confucianism, Taoism, Legalisam, Yin & Yang, Zhouyi and Feng & Shui (Wang, 1991, see Table 3). A systematic set of principles for managing the relationshops between man and environment, now called ecological aesthetics, was defined. The Chinese way to promote a sustainable future is to return to the naturalness of the ecosystem and the natural laws.

Based on the ancient human ecological philosophy in China and observing the interactions beteween natural and human-domiated ecosystems,ten cybernetical principles were derived for urban ecological regulation(Wangand Qi, 1991). Among them, the holism, symbiosis, recycling and self-reliance were always emphasized in ancient China. Indeed, in some cases the correlation between states of affairs in the natural and human worlds was thought to be so strongly causal in either or both directions,so that little action was carried out,prior to the undertaking of some divination procedure(Fung,1947). Such a strong view of correlation and interdependence would render distinctions between the human and the non-human,or the human and the natural,meaningless.

Table 3 The dynamic characteristics of transitional eco-coupling of urban system in China

Wang et al.(2011)defined the urban sustainability in China as a Social-Economic-Natural Complex Ecosystem(SENCE).Then,the ten principles were reduced into three categories(Wang and Ouyang,2001): competition for efficient resource and available of eco-niche;symbiosis between man and nature,among different groups of human beings,and between any human ecological unit and its upper level ecosystem;self-reliance to sustain its structural,functional and process stability through self-organisation and recycling.

Any weakening of these mechanisms will cause a decline in the urban sustainability. The representation of such a set of interrelations, with the purpose of representing the complexity of socio-ecological structure and its underlying bonds,is known under the general name of eco-coupling. Currently, the eco-coupling sustainability theories provide an eco-centric perspective to understand the complex interactions between humans and nature from an eco-centric point of view. Ecocentrism represents the broadest critique of reform environmentalism,due to its prescriptions for the rejection of the current dominant worldview,that perpetuates anti-ecological behaviors,promoting new personal connections with the natural world(Means,2013). The same author suggested that ecocentrism can find potential openings in emerging discussions of the precautionary principle in environmental decision-making practices–a principle that challenges the superiority and axiological priority granted to human well-being and development. Brown and Ulgiati(2011)also suggested redefining and redirecting human desires in ways that are less consuming of natural resources to achieve sustainability. According to Means(2013), definitive ecological constraints should be recognized to adjust and fit the scale of anthropogenic systems within the natural world. In the case of China,Hoffman(2014)proposed four alternative visions of future.The first one was characterized by a shift toward a greater democracy and human rights value. The second was a“golden age”one,within major scientific,political and cultural achievements. The third one was shallow and material. Finally, the fourth was a collapse of China, together with the world capitalist system. Looking to the found evidences,even if it cannot be claimed that pre-industrial cities were sustainable, it is possible to find the tendency of sustainability wisdom existed both in Europe and in China in the urban context. For example,it is evident that several actions were taken to guarantee the environmental sustainability, on which the survival of the urban population was strongly dependent(Although most actions were performed to overcome specific identified problems in that time, instead of looking for long-term environmental sustainability). Suggestions with regard to economic sustainability are less evident looking to the past,even if the problem of poverty eradication was known and taken into consideration. Social sustainability was supported by the existence of public inclusive spaces. Finally, the cultural sustainability is, maybe, the less evident, but more present factor in the medieval urban environment, where CES were existing and influenced the aesthetic and creative productions and where the dialogue and instruction was fostered by the birth and spreading of universities.

Different theories developed in the Chinese world witness that a reflection on the complex interplay between humans and the urban space already existed in the past. The question then arise: “can there be robust sustainability in future urban environments when socio-political landscape profess a vigorous dynamism?”. Any attempt to find a direct answer to this question should link the past(medieval age),the postmedieval,the present,and the future. It is worth noting that modern forces and policies of education,industrialisation, mechanization,electrification and urbanization have conspired to draw and subsequently disconnect people from patterns of past generations. The new type of industrial city, that is appearing all over China, has massively unsustainable character and so threatens China’s culture and environment(Levine et al.,2008;Verma and Raghubanshi,2018).There exist a total mislink of the social and cultural support, which characterized the pre-industial age cities.Thus,the theme of traditional ecological knowledge is important for the consideration of a broad range of questions related to present nature-human relations. Cleaner production can support such an action,which should be well planned,in order to obtain a transition toward sustainable and low-carbon societal lifestyles.

Finally, environmental monitoring and elaboration of available environmental data will play a crucial role in the process of potential adaptation of what we called sustainability wisdom into real urban environments.From a technological perspective, the use of proximal and remote sensing from aerial and satellite platforms can further enhance this process(e.g.: Lega and Napoli,2008;Nguyen et al.,2010a,b;Persechino et al.,2010;Lega and Persechino, 2014; Lega et al., 2014; Errico et al., 2015; Lin et al., 2015). The ability of correctly representing energy and resources flows is also important for drowing appropriate scenarios applied to urban,regional or national planning(Basosi et al.,2017;Li et al.,2017;Liu et al.,2017b,c). Moreover,the role of GIS representation of environmental data is now widely recognized by the scientific literature for this purpose(e.g.:S´aˇnka et al.,2014;Kanakiya et al.,2015;R´equia J´unior et al.,2015;Zou et al.,2015;Liu et al.,2016).

4 Conclusions

This paper is a first attempt to merge different factors existing in the pre-industrial age under the light of sustainability. The emerging body of sustainability wisdom might well complement the present drawing of scenarios for the future of world urbanization. Both empirical/field and post-processual research approaches are needed to further support the present body of knowledge in this field. In particular, the economic processes, even if already investigated,should be reinterpreted,as well as the social ones. This is also true in the case on interplay between the environment and culture trough the CES.The analysis, focused mainly on European and Chinese cities,might be also enlarged to other areas of the world.

With respect to the current state of the art,this work evidenced some limitations and potential directions for future research. The first intrinsic limitation is the lack of quantitative data and studies correlating the planning of urban spaces and the environmental conditions, which should be derived from proxy data (e.g.: climate data;archeobotanical data;palaeo-forensic data,that investigate the connection between state of burial remains with food habits; palaeo-forensic data on domesitc animal remains, such as bones, etc.). These data, often available from archaeological reports, are currently disconected and should be put in relation in future works.Only a recent book analyzed the relation between energy resources and pre-industrial cities (Margalit, 2016).Consequently,this research line is worth of further investigation. Economic data are sometimes available,in the case of small communities in medieval Europe,from old accounting records in monasteries(they are known as cartulari). The implementation of paleaographic research and translation of data into available databases would be really useful to understand the flow of resources, at least at local scale, implementing the knowledge on local-scale economies.

A second limitation consists in the current lack of translation of the existing body of knowledge about preindustrial urban sustainability into current practices and planning. This research aimed at giving a first integrated body of evidence on this topic. A possible path to follow to translate evidence into numbers would be to transform the information derived from archaeological and historical studies into sytemic models at urban scale. In fact,ecological discipline and its specific methods could support the integtration and augmentation of the available information collected through existing evidences. Isendahl(2016)discussed the role of historical ecology,being the study of “the role of environments in the development of social complexity and the examination of how social groups adapt to environmental conditions”. Previously,Trigger(1971)suggested the use of an opensystem approach to model the life of human communities in the past. However, this approach was not further pursued,because a clear and defined methodological framework in system ecology was still missing at that time.Conversely,today it is possible to move a step forward this direction. In fact,Howard Thomas Odum(September 1,1924–September 11,2002)developed a new integrative approach in ecology, based on the use of diagrams(Odum,2007),that can be transformed in to dynamic models, representing the stocks and flows of biophysical and socio-economic resources (i.e.: materials, energy, information, money, etc.) within a system (Odum and Odum, 2000). H. T. Odum referred to this holistic perspective calling a ‘macroscope’, contrasting the reductionist view previously applied in ecology(Madison,1997). For example,integrated models and simulations of resources flows at urban scale are available from the literature(Xue et al.,2018). The implementation of similar models for cities in the past would be useful to define some comparisons. Moreover,there are some studies that defined different sets of products baskets for pre-industrial communities, thus enabling to implement also the quantitative aspects of historical investigations (Malanima,2013).

The efficacy of future policies and planning measures will depend upon the ability of integrating the present knowledge with effective sustainable urban transition measures, in order to increase, from one side, the use of cleaner productions, and, on the other side, to increase their effectiveness and efficiency, contextualising them within a liveable and equitable context. This integration should be complemented with effective monitoring actions, which constitute both the mean for an adequate assessment of urban dynamics and an appropriate instrument for cheking the efficacy of taken actions. Thus,a further development of such a research could well support both policy-makers and urban planners in view of the urgent need of developing more sustainable and equitable post fossil carbon societies within the context of cities.

Acknowledgements

This work is supported by Beijing Science and Technology Planning Project(No. Z181100005318001), Sino-Italian Cooperation of China Natural Science Foundation(No. 71861137001)and the Italian Ministry of Foreign Affairs and International Cooperation, National Natural Science Foundation of China(No. 71673029) and the 111 Project(No. B17005).